Registration Dossier
Registration Dossier
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EC number: 926-099-9 | CAS number: -
Carcinogenicity
Administrative data
Description of key information
In 2001, the IARC Monograph Working Group convened to evaluate the carcinogenic potential of man made vitreous fibres (MMVFs), including those fulfilling Note Q criteria. Relevant literature on this topic up to 2001 was identified and reviewed by the Working Group. The Working Group classified insulation glass wool, rock/stone wool and slag wool as Group 3 substance (defined by IARC as “not classifiable as to its carcinogenicity to humans”). Since the publication of the 2002 IARC Monograph (Vol. 81), there as been an in vivo intraperitoneal chronic carcinogenicity study (published in two scientific articles) on Note Q MMVFs.
The evaluation of this in vivo study primarily showed no fibre-specific carcinogenic potential upon intraperitoneal exposure to Note Q MMVFs. It was shown in these studies that intraperitoneal injection of very high doses of one Note Q MMVF triggered an increased incidence of mesothelioma in rats, but there were non-fibre-specific non-neoplastic lesions (e.g. fibrous adhesion of abdominal organs) and decreased health status of high dose-exposed animals observed. The intraperitoneal injection especially of very high doses of the tested fibre caused diffuse fibrosis in the abdominal cavity, which can impair the health status and influences survival in all exposed animals. The most probable mechanism leading to tumor development is a persistent inflammation accompanied by a nodular fibrotic reaction. A persistent inflammation cell proliferation within these fibrotic nodules appears to be causal to the development of
mesothelioma originating from these nodules. The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas. Lastly, intraperitoneal injection of fibres is not a relevant route of human exposure to Note Q MMVFs.
Overall, there has been no evidence or study published after the 2002 IARC Monograph on MMVFs that contradicts the conclusion of IARC of classifying mineral wool fibres (insulation glass wool, stone/rock wool and slag wool) as Group 3 substance. Furthermore, by fulfilling the Note Q criteria under the EU CLP Regulation, Note Q man-made vitreous fibres are exonerated from classification for carcinogenicity.
Key value for chemical safety assessment
Carcinogenicity: via oral route
Link to relevant study records
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1998-2000
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations.
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- This study included one exposure level of the substance at 30 mg/m3 and a negative control group exposed to filtered air. The exposure duration was 6 hours/day, 5 days/week for 2 years with a subsequent postexposure period lasting approximately until 20% suvival in the control group.
- GLP compliance:
- yes
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- - Source: Charles River Laboratory, Raleigh, NC
- Age at study initiation: 7-8 weeks at delivery
- Weight at study initiation: approx. 180g at delivery
- Fasting period before study: no data
- Housing: individually or in groups of two
- Diet (e.g. ad libitum):ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: no data
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3°C
- Humidity (%): 30-70%
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12 - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Remarks:
- Nose-only flow-past technique
- Vehicle:
- clean air
- Remarks:
- filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Flow-past exposure chamber. Animals were confined separately in restraint tubes positioned radially at several levels of a vetical aerosol supplytube.
- Method of conditioning air: Electron charge neutralization with a Ni-63 line source.
- System of generating particulates/aerosols: The RCC fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber and oxygen concetrations were all monitored. - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Gravimetric concentration (mg/m3), WHO Fibers (fibers/cm3) and Fibers L>20µm (fibers/cm3) were monitored throughout the entire exposure period of two years.
- Duration of treatment / exposure:
- 6 hours/day, 5 days/week for 2 years with a subsequent postexposure period lasting approximately until 20% survival in the control group.
- Frequency of treatment:
- 6 hours/day, 5 days/week for 2 years
- Post exposure period:
- Until approximately 20% survival in the filtered air control group.
- Remarks:
- Doses / Concentrations:
30 mg/m3
Basis:
other: gravimetric concentration - No. of animals per sex per dose:
- 107
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: The gravimetric concentration of 30 mg/m3 was selected to obtain a fiber concentration of at least 259 WHO fibers/cm3 throughout the exposure period and for being comparable to other studies.
- Positive control:
- No positive control group entered in the study.
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes: clinical signs, morbidity and mortality
- Time schedule: Daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily
BODY WEIGHT: Yes
- Time schedule for examinations: Once a week during the first 13 wk, then every 2 wk.
NECROPSY was performed on all animals
- Sacrifice and pathology:
- Scheduled sacrifices after 3, 6, 12, 18 and 24 months of 5 animals per time-point.
- Statistics:
- Fischer's exact test, one-sided, for the incidence of broncho-alveolar hyperplasia, bronco-alveolar adenomas, and bronco-alveolar carcinomas in rats at risk for tumor formation. Dunnett test based on pooled variance for lung and body weights.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Histopathological findings: neoplastic:
- no effects observed
- Relevance of carcinogenic effects / potential:
- MMVF note Q fibres showed minimal collagen deposition, similar to what could be expected for any biologically inert dust at present exposure level. It is concluded that MMVF note Q fibres did not show a carcinogenic potential neither in the lungs nor in pleura.
- Dose descriptor:
- NOAEC
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: No statistically significant findings of broncho-alveolar hyperplasia, adenomas or carcinomas.
- Remarks on result:
- other: Effect type: carcinogenicity (migrated information)
- Conclusions:
- MMVF note Q fibres were not carcinogenic in the rat and induced only minimal collagen deposition in the lungs.
- Executive summary:
This is a comparable to guideline study with no deviations. Furthermore, it was published in a peer-reviewed scientific journal and details on the test materials and experimental design are very well documented. The objective of the study was to assess potential pathogenic and/or oncogenic effects of chronic inhalation exposure to stone wool fibers in rats.
107 male Fischer 344 rats were exposed 6 h/day, 5 days/week for 2 years to MMVF note Q fibres at 30 mg/m3 by nose-only inhalation of a well-characterized test atmosphere. The study showed that the MMVF note Q fibres possess neither fibrogenic nor carcinogenic potentials in the rat.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Methods of Sachsse et al. (1976); Hesterberg et al. (1991); Bernstein et al. (1993) and Cannon et al. (1983) were followed.
- GLP compliance:
- yes
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC.
- Age at study initiation: 6 weeks
- Housing: Polycarbonate cages
- Diet (e.g. ad libitum): Pelleted standard Kliba 343 rat maintenance diet
- Water (e.g. ad libitum): Filtered fresh water
- Acclimation period: 2 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+-3 oC
- Humidity (%): 30-70%
- Air changes (per hr): 20 air changes/hr
- Photoperiod (hrs dark / hrs light): 12-hr light/dark - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Vehicle:
- clean air
- Remarks:
- Filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Hazelton 2000 chamber
- Source and rate of air:
- System of generating particulates/aerosols:Research and Consulting Company, Geneva, fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber: 22+-3 oC, 30-70%, -20mm H2O
- Air change rate: 20 air change/hr
- Method of particle size determination: WHO Monograph 4 (WHO, 1985)
TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: yes - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Aerosol samples were collected on Gelman membrane filters in the same location as the animal exposure port. Fiber mass concentrations were determined once during pretest, and at least four times per week during the 2 year exposure period. To assure the uniformity of exposure the fiber concentrations were monitored continuously using a RAS (GCA Corp.) light scattering monitor.
Filter sampling was undertaken for each dose group. Samples were collected on Millipore filters, placed between glass slides, and clarified for counting.
Lung Burden Analysis
At necropsy the accessory lobe of the lung from each animal was removed and frozen. Diameter measurements and determination of the number of fibers recovered from the lungs were made at 5000X in a minimum of 20 fields or 200 fiber ends on either a JOEL T 300 SEM or a JOEL 840 SEM equipped with a Videoplan Image Analysis System according to the method outlined in WHO Monograph 4 for measuring airborne man-made mineral fibers (WHO, 1985) by scanning electron microscopy.
During preexposure trials and once every three months thereafter, MMVF note Q fibres' aerosols at each exposure concentration were captured on filters for determination of fiber length and diameter. - Duration of treatment / exposure:
- 24 months
- Frequency of treatment:
- 6 hr/day, 5 days/week
- Post exposure period:
- Until approximately 20% survival in the control group (30 months).
- Remarks:
- Doses / Concentrations:
3, 16, and 30 mg/m3
Basis:
nominal conc. - No. of animals per sex per dose:
- 140 (only male rats were used)
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: To allow comparison with concurrent studies
- Rationale for animal assignment (if not random): Random
- Rationale for selecting satellite groups: No data
- Post-exposure recovery period in satellite groups: 6 months
- Section schedule rationale (if not random): Random - Positive control:
- No
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once a week during the first 13 weeks and at least once a month thereafter.
BODY WEIGHT: Yes
- Time schedule for examinations: Once a week during the first 13 weeks and at least once a month thereafter.
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION: No data
OPHTHALMOSCOPIC EXAMINATION: No data
HAEMATOLOGY: No data
CLINICAL CHEMISTRY: No data
URINALYSIS: No data
NEUROBEHAVIOURAL EXAMINATION: No data
OTHER: - Sacrifice and pathology:
- Sceduled sacrifices were performed: 3 animals after 3 and 6 moths exposure and 6 animals after 12, 18 and 24 moths exposure.
GROSS PATHOLOGY: No
HISTOPATHOLOGY: Yes
Wagner Pathology Grading Scale was used:
Cellular Change
Normal 1 No lesion
Minimal 2 Macrophage response
Mild 3 Bronchioloization, inflammation, fibrosis
Minimal 4 Minimal
Mild 5 Linking of fibrosis
Moderate 6 Consolidation
Severe 7 Marked fibrosis and consolidation
8 Complete obstruction of most airways - Other examinations:
- No data
- Statistics:
- Pairwise comparison of tumor incidence between exposure groups were made using Fisher’s exact test, and tests for trend were made using an exact algorithm for the Cochran-Armitage test. All tests of significance were two-tailed, with no formal adjustment for multiple comparisons. The Student t-test was used for comparisons of the physical characteristics of the fibers.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- not specified
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not specified
- Haematological findings:
- not specified
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not specified
- Behaviour (functional findings):
- not specified
- Organ weight findings including organ / body weight ratios:
- not specified
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
-
HISTOPATHOLOGY: NON-NEOPLASTIC
There was no evidence of treatment-related interstitial lung fibrosis or pleural fibrosis at any time point in the study. Exposure to the substance was associated with nonspecific inflammatory response (macrophage response) in the lungs that did not appear to progress after 6-12 months of exposure. These cellular changes are reversible and are similar to the effects observed after inhalation of an inert dust. No lung fibrosis was observed.
HISTOPATHOLOGY: NEOPLASTIC (if applicable)
Exposure resulted in no mesotheliomas and no statistically significant increase in lung tumor incidence when compared to that of negative control group.
BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant body weight changes or excess mortality during the 2 years of exposure to the substance (data not shown). - Relevance of carcinogenic effects / potential:
- The study showed that 24 months inhalation exposure to MMVF note Q fibres (up to 30 mg/m3) did not induce lung fibrosis, mesothelioma and lung tumours as compared to the control animals.
- Dose descriptor:
- NOAEC
- Effect level:
- > 3 - <= 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: Lung burden of the substance after 3-24 months exposure to: 30 mg/m3 (3.72-5.03 fibers/mg dry lung x 10^3), 16 mg/m3 (2.09-3.46 fibers/mg dry lung x 10^3) and 3 mg/m3 (0.35-0.62 fibers/mg dry lung x 10^3), respectively
- Remarks on result:
- not determinable
- Remarks:
- no NOAEC identified. Effect type:other: lung burden (migrated information)
- Dose descriptor:
- NOEC
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: see 'Remark'
- Remarks on result:
- other: Effect type: toxicity (migrated information)
- Dose descriptor:
- NOAEL
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: No evidence of treatment-related interstitial lung fibrosis or pleural fibrosos. No biologically or statistically significant increase of lung tumor incidence.
- Remarks on result:
- other: Effect type: carcinogenicity (migrated information)
- Conclusions:
- The study shows that MMVF note Q fibres do not possess a potential for fibrotic or neoplastic changes in the lungs in rats.
- Executive summary:
This is a comparable to guideline study with no deviations. Furthermore, it was published in a peer-reviewed scientific journal and details on the test materials and experimental design are very well documented. The purpose of the study was to determine the chronic biological effects in Fischer 344 rats of inhaled size-separated respirable fractions of the substance. Rats were exposed either to the substance or to the filtered air (negative control) using nose-only inhalation chambers, 6 hr/day, 5 days/week, for 24 months to the concentrations of 3, 16 and 30 mg/m3. Exposure to the substance was associated with a nonspecific inflammatory (macrophage) response in the lungs that did not appear to progress after 6-12 months of exposure. No lung fibrosis was observed in the substance exposed animals, and the exposure resulted in no mesothelioma and no statistically significant increase in lung tumour incidence.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations.
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Methods and procedures of Hesterberg et al. (1998), Bernstein et al. (1995), Cannon et al. (1983), Law et al. (1990), Mast et al. (1995), McConnell et al. (1984) and Zoitos et al. (1997) were followed.
- GLP compliance:
- not specified
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River, Raleigh, NC)
- Housing: individually
- Diet (e.g. ad libitum): pelleted standard Kliba 343 ad libitum.
- Water (e.g. ad libitum): ad libitum.
- Acclimation period: acclimatized under laboratory conditions for at least 14 days prior to use
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3 °C
- Humidity (%): 30 to 70% relative humidity
- Photoperiod (hrs dark / hrs light): 12-h light/dark cycle - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Vehicle:
- clean air
- Remarks:
- filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: according to the method of Bernstein et al. (1995).
- Method of holding animals in test chamber: animals were confined separately in glass tubes positioned radially around the flow-past, nose-only exposure chamber (Cannon et al., 1983).
- Source and rate of air: 6h/day, 5days/week, for 2 years
- System of generating particulates/aerosols: RCC fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber: 22±3 °C, 30 to 70% relative humidity
- Method of particle size determination: Scanning electron microscopy (SEM, either a JEOL T 300 SEM or JEOL 840 SEM)
TEST ATMOSPHERE
- Brief description of analytical method used:
Numbers of fibers/mL in each of the aerosols and in the filtered air were determined at least once per week during the first 3 months and once ever 2 wks thereafter. Briefly, aerosol particles were collected on Gelman filters and were resuspended in filtered distilled water and collected onto Millipore filters (0.2-mm pore size). Millipore filters were mounted on a glass microscope slide and clarified with acetone, and fibers were counted on a Bausch and Lomb Balpan Phase Contrast microscope at a magnification of 4003. World Health Organization Monograph 4 counting rules were used for counting synthetic vitreous fibers/cc. Aerosol fiber dimensions were analyzed at least once during pretest, once per week during the first 4 weeks and once every 4 weeks thereafter. SVF aerosol fiber diameters were analyzed using scanning electron microscopy (SEM, either a JEOL T 300 SEM or JEOL 840 SEM) and lengths were analyzed using optical microscopy. Samples of aerosol were captured onto filters in the nose-port of an exposure chamber and stored until analysis (approximately 7 days) in sealed glass bottles containing 8% sodium azide/distilled water. At the time of analysis, to retain all fibers, each filter was washed into its bottle, the filter was ashed, and the ash was mixed back into the suspension. An aliquot was filtered through a 0.2-mm Nuclepore membrane, the membrane was dried, and either clarified on a glass microscope slide for optical length measurement or applied to a stub and gold coated for SEM. Diameter and length of aerosol fibers were measured in a minimum of 100 fibers or 20 fields; diameters were measured at 50003 and lengths were measured at 15003.
- Samples taken from breathing zone: yes, collected on Gelman membrane filters (No. 64515, Gelman Ltd., pore size 0.45 mm) - Analytical verification of doses or concentrations:
- yes
- Duration of treatment / exposure:
- 2 years
- Frequency of treatment:
- 6 h/day, 5 days/week, 2 years
- Post exposure period:
- 23-week exposure-free recovery period
- Remarks:
- Doses / Concentrations:
30 mg/m3
Basis:
nominal conc. - No. of animals per sex per dose:
- 140
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: The target aerosol concentration, 30 mg/m3 (approximately 180 WHO fibers/cc), was chosen as the maximum dose. Previously reported studies indicate that exposure concentrations higher than this can overload lung clearance mechanisms and cause respiratory effects that are not specific to the fiber composition
- Positive control:
- Filtered air.
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All animals were examined for clinical signs of toxicity before the start and after the completion of each exposure day and at least once on nonexposure days.
DETAILED CLINICAL OBSERVATIONS: No data
BODY WEIGHT: Yes
- Time schedule for examinations: Body weights of all animals were monitored weekly during the study period.
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: No
CLINICAL CHEMISTRY: No
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No - Sacrifice and pathology:
- Necropsy was performed on three to six animals immediately after 13, 26, 39, 52, 78, and 104 weeks of exposure and after various post exposure recovery periods.
GROSS PATHOLOGY: No
HISTOPATHOLOGY: Yes - Other examinations:
- - Lung burden analyses: Inhaled fibers were recovered from the right accessory lobe of the lung and were analyzed.
- Statistics:
- Dunnett test based on pooled variance (on organ and body weight results).
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Description (incidence and severity):
- Body weights of Note Q MMVF-exposed animals tended to be 2 to 3% greater than air controls; these differences occasionally reached statistical significance (Dunnett test based on pooled variance, 1% level; data not shown in paper).
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- Irritation (cellularity and inflammation)
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
- Pulmonary changes induced by Note Q MMVF fibres were limited to irritation (cellularity and inflammation), and they did not induce fibrosis or neoplasms.
- Relevance of carcinogenic effects / potential:
- The study showed that 24 months inhalation exposure to MMVF note Q fibres (30 mg/m3) did not induce lung fibrosis, mesothelioma or lung tumours as compared to the control animals, and only minimal lung cellularity that reversed after exposure was terminated.
- Dose descriptor:
- NOAEC
- Effect level:
- ca. 30 mg/m³ air (analytical)
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: histopathology
- Remarks on result:
- other:
- Remarks:
- Effect type: other: Irritation (cellularity and inflammation) (migrated information)
- Conclusions:
- MMVF note Q fibres are neither fibrogenic nor tumourigenic and induced only minimal lung cellularity that reversed after exposure was terminated.
- Executive summary:
The effects of long-term inhalation of MMVF note Q fibres were studied in rats. Of primary concern was the importance of biopersistence as a mechanism of fibre toxicity. Male Fischer rats were exposed to fibre aerosol by nose-only inhalation for 6h/day, 5 days/week for 2 years. The fibre concentration was ~30 mg/m3. MMVF note Q fibres were neither fibrogenic nor tumourigenic and induced only minimal lung cellularity that reversed after exposure was terminated.
- Endpoint:
- carcinogenicity, other
- Remarks:
- Intraperitoneal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- - Principle of test:
Long-term intraperitoneal carcinogenicity test in rats
- Parameters analysed / observed: mortality, morbidity, clinical signs, body weight, presence of palpable masses, ascites fluid, detailed macroscopic post-mortem observation of organs or tissues - GLP compliance:
- yes
- Remarks:
- The study was performed in compliance with the Good Laboratory Practice Regulations (Council Directive 87/18/EEC of 18 December 1986) and the EEC Animal Health Regulation (Council Directive 86/609/EEC of 24 November 1986).
- Specific details on test material used for the study:
- SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: The soluble insulation wools (i.e. fibres B, M, O, P, V) were produced by Saint Gobain SA, Paris, and the crocidolite was provided by Johns Manville Corporation (Mountain Technical Center, Denver, CO).
The following Note Q MMVFs were tested: fibre B (glass wool), fibre M (insulation glass wool), fibre O (silicate stone wool), fibre P (insulation glass wool), fibre V (insulation glass wool) - Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River, France
- Age at study initiation: 8 weeks old
- Weight at study initiation: 209 g
- Housing: housed in a barrier rodent unit under the same conditions as described by Lambre et al., 1998 (Inhal Toxicol 10:995-1021). - Route of administration:
- intraperitoneal
- Vehicle:
- other: saline
- Details on exposure:
- The test substance was administered by intraperitoneal injection in a volume of 2.5 ml saline/injection animal. The injections were performed in the left part of the abdomen (to avoid trauma to the liver), approximately half-way between the xiphoid appendix and genitalia. The rat was maintained manually by a technician in an almost vertical position with the skin in tension. The needle connected to the syringe was inserted by a second technician, perpendicularly to the skin, and then the suspension of fibers was injected gently. A plastic syringe (Terumo, 2-ml syringe, Luer, actual capacity 2.5 ml) fitted with a single-use metal needle (Terumo, Neolus needle, Luer, 20G × 1, 0.9 × 25 mm in first instance, or 18G × 1.5, 1.2 × 40 mm if problems of plugging were encountered) was used. The injections were performed at 1-week intervals without anaesthesia for 2, 8, or 20 times, depending upon the total dose that was to be injected.
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The control of the actual quantities of test substances injected was performed during the course of administration for all groups except the two
negative control groups, using sham injections made into a glass vial. This procedure was performed for each test substance during the course of the 1st, 7th, 14th, and 20th series of injections, and the samples were analysed either gravimetrically or by scanning electron microscopy (SEM) if the weighing results were too disperse. - Duration of treatment / exposure:
- For Note Q MMVFs: Weekly injection with 2 (amounting to 500 x 10^6 fibres), 8 (amounting to 2000 x 10^6 fibres), 20 (amounting to 5000 x 10^6 fibres) injections
For crocidolite: a single injection of 100×10^6 or 1000 × 10^6 - Frequency of treatment:
- Weekly for Note Q MMVFs
Single injection for crocidolite - Post exposure period:
- The study was terminated after 123 wk of observation following the start of exposure, when the survival rate in both negative control groups
reached 20%. - Dose / conc.:
- 500 000 000 other: WHO fibers
- Remarks:
- Tested with fibres M, O, P and V
- Dose / conc.:
- 2 000 000 000 other: WHO fibers
- Remarks:
- Tested with fibres B, M, O, P and V
- Dose / conc.:
- 5 000 000 000 other: WHO fibers
- Remarks:
- Tested with fibres B, M, O, P and V
- No. of animals per sex per dose:
- 51 females per group
- Control animals:
- yes, concurrent no treatment
- yes, concurrent vehicle
- Details on study design:
- - Short description of test conditions:
Eighteen experimental groups, each comprising 51 female rats of the Wistar strain, Crl (WI) BR (Charles River, Saint-Aubin lès Elbeuf, France), were used as follows:
• one group received no injection and acted as an absolute negative control group;
• one group received 20 injections of saline solution and acted as a vehicle negative control group;
• two groups received a single injection of 100 x 10^6 or 1000 x 10^6 fibres of crocidolite and acted as positive control groups;
• two groups received 8 or 20 injections of fibre B (glass wool), to achieve a total of 2000 x 10^6 or 5000 x 10^6 fibres, and acted as ‘soluble-fibre’ reference groups;
• three groups received 2, 8 or 20 injections of fibre M (insulation glass wool) to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre O (stone wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre P (insulation glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre V (insulation glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres.
The intraperitoneal injections were carried out at one week intervals. - Positive control:
- Yes, single injection of 100 × 10^6 or 1000 × 10^6 fibres of crocidolite
- Observations and examinations performed and frequency:
- MORBIDITY AND MORTALITY: Yes
- Time schedule: The animals were checked at least twice a day for mortality or signs of morbidity.
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Each animal was observed for clinical signs at least once a day. From week 27 onward, animals were palpated every 2 week and the date of appearance, size and location, and any changes of observed masses were recorded. Ascites fluid was collected at the beginning of necropsy by puncturing the abdomen. The following parameters were measured: volume; color, fluidity, and transparency by visual assessment, and total proteins in g/L.
BODY WEIGHT: Yes
- Time schedule for examinations: recorded once before allocation of the animals to groups, on the day before the first treatment, at week 2, once a week during the first 13 week of study, and then once every 4 week until the end of the study.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes - Statistics:
- Wilcoxon test for survival data; other statistical tests used but not specified in study
- Clinical signs:
- no effects observed
- Description (incidence and severity):
- The volumetric quantification of ascites fluid from those animals killed at terminal sacrifice showed no significant association with any of the dose or fibre type. The protein content of the fluid ranged from 29 to 44 g/L in 39 samples.
- Dermal irritation (if dermal study):
- not examined
- Mortality:
- mortality observed, treatment-related
- Description (incidence):
- Compared to the saline controls, both doses of crocidolite and the B fibre (5 × 10^9 WHO fibres) groups had a statistically significant reduction in survival. The median survival of this control group was 110 weeks after start of exposure. For the positive control group exposed with 0.5 mg (0.1 x 10^9 WHO fibres) crocidolite the median survival was 97 weeks, and for the B fibre (5 × 10^9 WHO fibres) groups the median survival was 94 weeks.
For all other dose groups of the remaining fibres, there was no statistically significant difference in the survival curves compared to the saline control group. - Body weight and weight changes:
- effects observed, non-treatment-related
- Description (incidence and severity):
- There was no statistically significant differences in mean body weight between the saline-injected control animals and the untreated control animals. Occasional statistically significant differences in mean body weights were observed; however, no systematic differences that could be related to exposure were found. The two control groups are marked, as well as the high dose crocidolite, which had a body weight peak at the 98th week and fibre P high dose had a slightly lower body weight curve.
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- not examined
- Gross pathological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- The most important exposure-related findings were:
1. The palpable masses recorded during the study were observed at a similar incidence and occurrence in both control and treated animals and showed no indication of treatment or dose relationship in size, location, multiplicity, or morphological type.
2. Fibrous adhesions: The previous study had shown that the intraperitoneal injection of ~1 mg resulted in a substantial incidence of fibrotic adhesions compared to the saline control groups. In this study, almost all of the supplementary animals killed at week 21 showed fibrous adhesions. Exposed animals had a high incidence of fibrous adhesions between abdominal organs, most frequently involving liver and diaphragm. The fibrous adhesions were mainly composed of mature collagen fibres, with some occasional fibrocytes. There was an exponential relationship between the total number of adhesions per group and the incidence of mesothelioma when the two crocidolite groups are excluded. For crocidolite, fewer adhesions were noted with a high level of tumours (lower dose: 43 adhesions/27 mesotheliomas; higher dose: 141 adhesions/45 mesotheliomas), suggesting a different mechanism of action for crocidolite as compared to the soluble mineral fibres. The macroscopic findings on the distribution of fibrous adhesions were confirmed by subsequent microscopic examination.
3. Abdominal cavity nodules or masses: The occurrence of nodules and masses above a baseline of approximately six per animal was correlated to the incidence of mesothelioma. Subsequent microscopic examination showed that the fibrotic nodules were composed mainly of fibroblasts, macrophages, and giant cells intermingled with test fibres of variable size and of a variable amount of connective tissue.
4. Incidence of animals with ascites: The incidence of animals with ascites was found to be highly correlated with the incidence of nodules and masses at different sites. The difference between the tested fibres and the insoluble crocidolite in the association of the incidence of nodules and ascites is very clear. - Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- In some animals a chronic inflammatory reaction was observed, which was characterised by a cellular reaction composed mainly of macrophages, fibroblasts and GI cells with variable degree of fibrosis (collagen fibre formation). The highest frequency was observed in the liver. There was a statistically significant association total incidence with the incidence of mesothelioma although with a greater variation at the lower incidences of mesothelioma. Crocidolite appears to have a different association, reinforcing the concept that the tumorigenic mechanism in the intraperitoneal cavity is different for the massive doses of the soluble tested fibres as compared to the lower doses of insoluble crocidolite. Other nonneoplastic findings besides fibrotic and inflammatory reactions unrelated to exposure were observed as would be expected in this age and strain of rats.
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- Mesothelioma was detected with variable incidence and histological subtypes among fibre-treated animals except for the groups treated with fibres M and O (there was one single case in high dose group of O fibre). The microscopic investigation revealed that the mesothelioma developed from the observed fibrotic nodules. The mesotheliomas were always found at sites where macroscopic changes (adhesions, nodules) were seen.
Mesotheliomas were first classified according to their behaviour: (1) Miliary, when the mesothelioma comprised a number of nodules spreading on the peritoneal surface of the abdominal organs; (2) Creeping, when the mesothelioma showed a massive spread on the peritoneal surface and sometimes covering the whole surface of most of the abdominal organs or even infiltrating some organs. Then each category was subdivided according to the microscopic appearance of the cellular elements: (1) epithelial, (2) mesenchymal, and (3) mixed. Only three cases of “true epithelial mesothelioma” were registered.
The malignant tumours defined as abdominal tumours with serosal spread (ATSS) were all diagnosed as primary tumours (from mostly the uterus) with metastasis in the serosa as well as other abdominal organs. These ATSS were of low frequency, between 0 and 4 cases per group and were not considered exposure-related.
Histiocytic sarcoma, found in only a few animals, was not exposure related. This finding was similar to that reported among rats of this sex, age, and strain. The incidence of other neoplastic lesions (except mesothelioma) was not found to be dose related.
The information on neoplastic findings for this high dose study leads to the conclusion that mesothelioma of different histological subtypes is the only tumour type clearly related to treatment. - Details on results:
- This study has demonstrated the following:
1. The intraperitoneal injection especially of very high doses of these fibres causes diffuse fibrosis in the abdominal cavity, which can impair the health status and influences survival in all exposed animals. The most probable mechanism leading to intraperitoneal tumour development is a persistent inflammation accompanied by a nodular fibrotic reaction. A persistent inflammation cell proliferation within these fibrotic nodules appears to be causal to the development of mesothelioma originating from these nodules.
2. The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas.
3. Differences in aetiology were observed between the massive doses of the highly soluble insulation wools when injected directly into the intraperitoneal cavity and the lower doses of the extremely insoluble fibre crocidolite. The variability in this reaction and the impairment of animal health puts into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools.
4. All of the synthetic mineral wool fibre types tested in this study meet the Note Q criteria under CLP Regulation. - Relevance of carcinogenic effects / potential:
- One of the Note Q criteria under CLP Regulation states that a fibre need not be classified as a carcinogen if “an appropriate intraperitoneal test has shown no evidence of excess carcinogenicity.” All of the fibre types tested in this study meet the EC criteria for exoneration (i.e. Note Q). In addition, there is no statistical difference between the results of fibre B and the other synthetic mineral wool fibres tested in this study.
- Conclusions:
- All of the tested mineral wool fibre types in this study meet the Note Q criteria under CLP Regulation (“an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity”).
- Executive summary:
Female Wistar rats (51/group) were exposed intraperitoneally to five soluble mineral wool fibres (fibres B, M, O, P and V), which were injected weekly at total dose levels ranging from 500 to 5000 × 10^6 WHO fibres. There were also negative control (no treatment), vehicle control (saline) and positive control (crocidolite) used in this study. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups).
The tested soluble mineral wool fibres did not produce statistically significant adverse effects on the basis of mortality, clinical signs and body weight. Two of the new insulation wools, fibres M and O, showed no statistically significant tumorigenic response even at the very high dose of 5 × 10^9 WHO fibers injected. Fibres P and V showed a small tumorigenic response in the intraperitoneal cavity similar in magnitude to the B fibre. The response to the soluble insulation fibres was notably different from that of the known carcinogen crocidolite, which produced 53% tumours at a comparatively low dose of 0.1 × 10^9 WHO fibres.
The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas. Differences in aetiology were observed between the massive doses of the highly soluble insulation glass wools when injected directly into the intraperitoneal cavity and the lower doses of the extremely insoluble fiber crocidolite. The variability in this reaction and the impairment of animal health put into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools.
All of the tested mineral wool fibre types in this study meet the Note Q criteria under CLP Regulation (“an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity”).
- Endpoint:
- carcinogenicity, other
- Remarks:
- Intraperitoneal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Principles of method if other than guideline:
- - Principle of test: The long-term intraperitoneal test in rats is generally regarded as a suitable model for evaluating man-made vitreous fibres (MMVFs) for carcinogenic potential because of (1) similarities of responses at the serosal level in the abdominal cavity, compared to those occurring at the pulmonary level and (2) experimental work on natural (particularly various asbestos types) and synthetic fibres, which confirmed a high sensitivity on the basis of induction of mesotheliomas.
- Parameters analysed / observed: mortality, morbidity, clinical signs, body weight, presence of palpable masses, ascites fluid, detailed macroscopic post-mortem observation of organs or tissues - GLP compliance:
- not specified
- Specific details on test material used for the study:
- The following Note Q MMVFs were tested: fibre B (borosilicate glass wool), fibre M (borosilicate glass wool), fibre O (silicate stone wool), fibre P (borosilicate glass wool), fibre V (borosilicate glass wool)
- Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Route of administration:
- intraperitoneal
- Vehicle:
- other: saline
- Details on exposure:
- PREPARATION OF DOSING SOLUTIONS: The volume of the fibre suspension administered was 2.5 ml/injection/animal.
- Analytical verification of doses or concentrations:
- not specified
- Details on analytical verification of doses or concentrations:
- not specified
- Duration of treatment / exposure:
- For Note Q MMVFs: Weekly injection with 2 (amounting to 500 x 10^6 fibres), 8 (amounting to 2000 x 10^6 fibres), 20 (amounting to 5000 x 10^6 fibres) injections
For crocidolite: a single injection of 100×10^6 or 1000 × 10^6 - Frequency of treatment:
- Weekly for Note Q MMVFs
Single injection for crocidolite - Post exposure period:
- 123 weeks of observation
- Dose / conc.:
- 500 000 000 other: WHO fibres
- Remarks:
- Tested with fibres M, O, P and V
- Dose / conc.:
- 2 000 000 000 other: WHO fibres
- Remarks:
- Tested with fibres B, M, O, P and V
- Dose / conc.:
- 5 000 000 000 other: WHO fibres
- Remarks:
- Tested with fibres B, M, O, P and V
- No. of animals per sex per dose:
- 51 female rats per group
- Control animals:
- yes, concurrent no treatment
- yes, concurrent vehicle
- Details on study design:
- - Short description of test conditions:
Eighteen experimental groups, each comprising 51 female rats of the Wistar strain, Crl (WI) BR (Charles River, Saint-Aubin lès Elbeuf, France), were used as follows:
• one group received no injection and acted as an absolute negative control group;
• one group received 20 injections of saline solution and acted as a vehicle negative control group;
• two groups received a single injection of 100 x 10^6 or 1000 x 10^6 fibres of crocidolite and acted as positive control groups;
• two groups received 8 or 20 injections of fibre B (borosilicate glass wool), to achieve a total of 2000 x 10^6 or 5000 x 10^6 fibres, and acted as ‘soluble-fibre’ reference groups;
• three groups received 2, 8 or 20 injections of fibre M (borosilicate glass wool) to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre O (silicate stone wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre P (borosilicate glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre V (borosilicate glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres.
The intraperitoneal injections were carried out at one week intervals. - Positive control:
- Yes, single injection of 100 × 10^6 or 1000 × 10^6 fibres of crocidolite
- Observations and examinations performed and frequency:
- The animals were checked daily for mortality, morbidity and clinical signs. Body weight and presence of palpable masses were recorded at regular intervals. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups). In any decedent or surviving animals, ascites fluid was collected (when present) and analysed. A detailed macroscopic post-mortem observation was carried out. A full range of organs or tissues was sampled. Designated organs were then examined microscopically: organs and tissues of the abdominal cavity, palpable masses and macroscopic lesions. This examination focused on carcinogenic effects, in particular on possible tumours of the abdominal cavity, especially mesotheliomas.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes - Statistics:
- Dunnett's test for body weight
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- - Signs of ascites formation in the abdomen, in the groups injected with crocidolite, fibres B and P (marked), fibre V (moderate) and with fibre O (slight).
- Signs of anaemia in the groups injected with crocidolite and fibre B (all dose-levels). This correlated with the presence of haemorrhagic ascites fluid. - Mortality:
- mortality observed, treatment-related
- Description (incidence):
- - The 20 injections of saline solution produced a slight increase of mortality rate, when compared to the absolute control animals.
- The injection of crocidolite produced a marked increase of mortality at both dose levels.
- The injection of fibres M, O, P and V did not increase the normal mortality rate regardless of the dose level.
- The injection of fibre B produced a slight increase of mortality, but only at the high dose level (i.e. 5000 × 10^6 fibres). - Body weight and weight changes:
- effects observed, non-treatment-related
- Description (incidence and severity):
- - The 20 injections of saline solution did not produce an effect on body weight gain when compared to the absolute control animals.
- The injection of fibres M, O and P produced a slight decrease of body weight gain but only at the high dose level (5000 × 10^6 fibres).
- The injection of fibre V did not produce an effect on body weight gain regardless of the dose level.
According to the key study of Grimm et al., 2002, which is the same study as this one, it was mentioned that "there was no statistically significant differences in mean body weight between the saline-injected control animals and the untreated control animals. Occasional statistically significant differences in mean body weights were observed; however, no systematic differences that could be related to exposure were found." - Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not specified
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not specified
- Organ weight findings including organ / body weight ratios:
- not specified
- Gross pathological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- The macroscopic lesions produced by the injection of fibres were confined to the abdominal cavity.
- There were fibrous adhesions between various abdominal organs in all fibre-injected groups, with a dose-related incidence and severity: for crocidolite (high), fibres B, P and V (moderate), and fibres M and O (low).
- There were nodules or masses on the diaphragm, abdominal wall, adipose tissue and mesentery/ abdominal cavity with a dose-related incidence and severity (similar to fibrous adhesions): for crocidolite (high), fibres B, P and V (moderate), and fibres M and O (low). - Neuropathological findings:
- not specified
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- The non-neoplastic lesions observed at microscopic examination and attributable to the injection of fibres. They were confined to fibrous adhesion between numerous organs in the abdominal cavity in almost all fibre-injected animals (except crocidolite at the low dose level). The severity was dose-related for crocidolite (moderate to marked), fibres B, P and V (slight to moderate), and fibres M and O (minimal to slight). These findings were sometimes associated with chronic peritonitis with fibrotic nodules or hepatocellular necrosis.
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- The neoplastic lesions observed at microscopic examination and attributable to the injection of fibres were limited to mesothelioma in the abdominal cavity.
From this point of view, the following classification can be made:
- no mesothelioma: negative control groups, fibres M and O;
- low occurrence of mesothelioma (4–28% of the animals): fibres B, P and V;
- high occurrence of mesothelioma (53–90% of the animals): crocidolite.
Besides mesothelioma, the tumour profile of the animals was not modified in any group: the nature, incidence and latency of the other neoplastic lesions was similar to what can be expected for animals of this strain and age. - Other effects:
- not specified
- Relevance of carcinogenic effects / potential:
- 1. no mesothelioma: negative control groups, fibres M and O;
2. low or moderate occurrence of mesothelioma (4–28% of the animals): fibres B, P and V. - Conclusions:
- The tested soluble mineral wool fibres (B, M, O, P and V) did not produce notable adverse effects on the basis of mortality, clinical signs and body weight except at high dose levels. Histopathological investigations distinguished the various fibres:
* Fibres M and O did not induce mesotheliomas at tested doses up to 5000 × 10^6 fibres;
* Fibres P and V induced up to 16% and 28%, respectively, of mesotheliomas at the same dose of 5000 x 10^6 fibres and in the same range as for the reference fibre B (18% of animals with mesotheliomas).
* 90% of the crocidolite-treated animals displayed mesotheliomas at a dose level of 1000 × 10^6 fibres.
This interpretation of this study is given more in details in other key study of Grimm et al. (2002), which concluded that all the tested soluble mineral wool fibres fulfilled the Note Q criteria under CLP Regulation (“an appropriate intraperitoneal test has not expressed signs of excessive carcinogenicity"). - Executive summary:
Female Wistar rats (51/group) were exposed intraperitoneally to five soluble mineral wool fibres (fibres B, M, O, P and V), which were injected weekly at total dose levels ranging from 500 to 5000 × 10^6 WHO fibres. There were also negative control (no treatment), vehicle control (saline) and positive control (crocidolite) used in this study. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups).
The tested fibres did not produce notable adverse effects on the basis of mortality, clinical signs and body weight except at high dose levels. Histopathological investigations distinguished the various fibres:
* Fibres M and O did not induce mesotheliomas at tested doses up to 5000 × 10^6 fibres;
* Fibres P and V induced up to 16% and 28%, respectively, of mesotheliomas at the same dose of 5000 x 10^6 fibres and in the same range as for the reference fibre B (18% of animals with mesotheliomas).
* 90% of the crocidolite-treated animals displayed mesotheliomas at a dose level of 1000 × 10^6 fibres.
This interpretation of this study is given more in details in other key study of Grimm et al. (2002), which concluded that all the tested soluble mineral wool fibres fulfilled the Note Q criteria under CLP Regulation (“an appropriate intraperitoneal test has not expressed signs of excessive carcinogenicity").
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- other: IARC monograph
- Adequacy of study:
- supporting study
- Reliability:
- 3 (not reliable)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- This publication evaluates the carcinogenic risks of man-made vitreous fibers in humans with the help of international working groups of experts prepared, critical reviews and evaluations of evidence on the carcinogenicity of a wide range of human exposures.
- GLP compliance:
- no
- Remarks on result:
- not determinable
- Remarks:
- Critical literature review
- Critical effects observed:
- not specified
- Conclusions:
- Based on the presented data in the publication, “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, man-made vitreous fibres made of glass, rock/stone or slag wool are classified as Group 3 (‘not classifiable as to its carcinogenicity to humans’) substances.
- Executive summary:
In the publication “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, several studies on carcinogenicity conducted with MMVFs were evaluated and presented. These studies include human carcinogenicity case-control and cohort studies, animal experiments on carcinogenicity as well as deposition and retention studies, fibre biopersistence and in vitro dissolution studies.
For all MMVFs considered by the IARC Working Group in 2001, there is inadequate evidence for carcinogenicity in humans on the basis of epidemiological information. The final evaluations of these products thus depended on the animal carcinogenicity data. Overall, MMVFs made of glass, rock/stone and slag wool are classified as Group 3 (‘not classifiable as to its carcinogenicity to humans’)substances.
Referenceopen allclose all
Summary incidence of broncho-alveolar hyperplasia, bronco-alveolar adenomas, and bronco-alveolar carcinomas in rats at risk for tumor formation:
Group |
n |
Broncho-alveolar hyperplasia |
Adenoma |
Carcinoma |
Carcinoma + adenoma |
||||
n |
% |
n |
% |
n |
% |
n |
% |
||
MMVF note Q fibres |
107 |
6 |
5.6 |
5 |
4.7 |
0 |
0.0 |
5 |
4.7 |
Control |
107 |
4 |
3.7 |
3 |
2.8 |
1 |
0.9 |
4 |
3.7 |
Note. n, Number of animals "at risk" (defined as the number of animals sacrified at the end of the 12-month exposure period, and the number of animals subsequently found dead or sacrified until the termination of the study, provided that they were exposed for at least 12 months and that their lungs were examined histologically).
Statistical method: Exposed group compared to concurrent control using Fischer's exact test, one-sided. [No statistically significant findings at 5% level].
Average Wagner Scores in rats to filtererd air, or MMVF note Q fibres:
Euthanize/exposure (months) |
Air control |
MMVF note Q fibres |
||
3 mg/m3 |
16 mg/m3 |
30 mg/m3 |
||
Continous exposure |
||||
3/3 |
1.0 |
2.0 |
2.0 |
3.0 |
6/6 |
1.0 |
2.0 |
2.3 |
3.0 |
12/12 |
1.0 |
2.2 |
3.0 |
3.0 |
18/18 |
1.0 |
2.5 |
3.0 |
3.0 |
24/24 |
1.0 |
2.5 |
2.7 |
2.5 |
Recovery |
||||
24/3 |
1.0 |
1.2 |
2.0 |
2.0 |
24/6 |
1.0 |
1.5 |
2.0 |
2.2 |
24/12 |
1.0 |
2.0 |
2.0 |
2.0 |
24/18 |
1.0 |
2.0 |
2.5 |
2.2 |
30/24 c |
1.0 |
2.0 |
2.2 |
2.5 |
c: These animals represent the terminal euthanization which occurred when animal survival was approximately 20%.
Summary of Lung Tumor Findings:
Exposure group |
At risk b |
Adenomas |
Carcinomas |
Total lung tumors |
Mesotheliomas |
Controls |
123 |
3 (2.4%) |
1 (0.8%) |
4 (3.3%) |
0 |
3 mg/m3 |
118 |
3 (2.5%) |
1 (0.9%) |
4 (3.4%) |
0 |
16 mg/m3 |
120 |
6 (5.0%) |
3 (2.5%) |
9 (7.5%) |
0 |
30 mg/m3 |
112 |
3 (2.7%) |
0 |
3 (2.7%) |
0 |
b: Only animals that were exposed to fibers for at least 1 year were considered at risk for induction of neoplasms as this was the earliest time point a neoplastic finding was observed in this series of studies.
Pulmonary and Mesothelial Proliferative Lesions
Exposure |
Nb |
Hyperplasia (bronchioalveolar)a |
Lung cancera |
Mesothelioma (pleural)a |
||
Adenoma |
Carcinoma |
Total lung cancers |
||||
Air |
130 |
5 (3.8) |
2 (1.5) |
0 |
2 (1.5) |
0 |
MMVF note Q fibres |
121 |
6 (4.9) |
1 (0.8) |
1 (0.8) |
3 (1.6) |
0 |
Note.No significant findings.
a Values are the total number of X. Values in parentheses are percentages.
b Number of animals at risk for tumor formation (at-risk defined as surviving until at least the 12-month time point, after first tumor appeared).
Pulmonary Change: Mean Wagner Scorea
Exposure / Recovery (weeks) |
Air control (Exposure only) |
MMVF note Q fibres |
|
Exposure |
Recovery |
||
13/91 |
1.3 |
2.0 |
1.3 |
26/78 |
1.0 |
2.0 |
1.0 |
39/65 |
1.0 |
2.3 |
1.0 |
52/52 |
1.0 |
3.0 |
2.5 |
65/nd |
1.0 |
3.0 |
nd |
78/26 |
1.0 |
3.0 |
2.0 |
104/23 |
1.0 |
2.8 |
2.7 |
For exposure animals, n = 3–6; for 104+23 week time point, n = > 10; for interim recovery groups, n = 2–4 due to decreasing suvival. nd, not done.
a Scores according to Wagner, 1984. Scale: 1, no lesion; 2, macrophage aggregation; 3, cellularity; 4, fibrosis (irreversible); 5, linking fibrosis.
Inflammation and Collagen Deposition in the Lung and Pleura
Exposure / Recovery (weeks) |
Alveolar macrophage aggregation a |
Alveolar bronchiolization a |
Microgranulation a |
Bronchioalveolar collagen a |
Pleural collagen a |
|||||
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
|
13/91 |
1.0 |
1.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
26/78 |
1.3 |
0.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
39/65 |
2.0 |
1.0 |
0.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
52/52 |
2.0 |
1.5 |
1.2 |
0.5 |
0 |
0.5 |
0 |
0 |
0 |
0 |
78/26 |
2.3 |
2.0 |
2.0 |
0 |
2.0 |
0.5 |
0 |
0 |
0 |
0 |
104/23 |
2.1 |
2.1 |
1.0 |
0.8 |
1.2 |
1.5 |
0 |
0 |
0 |
0 |
Note.Level of severity of lesions observed at time points during 2-year exposure period and 6-month recovery period was graded as follows: grade 0, normal; 1, minimal; 2, mild; 3, moderate; 4, marked; 5, massive. Each grade is a mean of 3–10 animals.
a Expos. indicates animals had exposure but not recovery time; recov. indicates animals had exposure + recovery.
Table: Summary of survival rate, body weight and incidence of ascites fluid
| Group | Test material | Dose level (x10^6 WHO fibres) | Median survival (weeks) | Body weight in study week 78 (grams) | Incidence of ascites fluid |
| 1 | Untreated | 0 | 118 | 512 | 0 |
| 2 | Saline | 0 | 113 | 512 | 0 |
| 3 | Crocidolite | 100 | 105 | 498 | 27 |
| 4 | 1000 | 67 | 486 | 49 | |
| 5 | Fibre B | 2000 | 121 | 473* | 6 |
| 6 | 5000 | 100 | 490 | 23 | |
| 7 | Fibre M | 500 | 112 | 495 | 4 |
| 8 | 2000 | 119 | 507 | 3 | |
| 9 | 5000 | 114 | 480 | 6 | |
| 10 | Fibre O | 500 | 104 | 506 | 2 |
| 11 | 2000 | 115 | 498 | 4 | |
| 12 | 5000 | 119 | 486 | 10 | |
| 13 | Fibre P | 500 | 110 | 499 | 1 |
| 14 | 2000 | 120 | 494 | 16 | |
| 15 | 5000 | 112 | 456** | 36 | |
| 16 | Fibre V | 500 | 119 | 488 | 8 |
| 17 | 2000 | 117 | 494 | 7 | |
| 18 | 5000 | 109 | 508 | 27 |
* p < 0.05; p < 0.01 (Dunnett's test).
Table: Summary of microscopic findings
| Group | Test material | Dose level (x10^6 WHO fibres) | Abdominal adhesion (total # of events)a | Chronic peritonitis (total # of events) | Mesotheliomas (# animals affected/# animals examined) |
| 1 | Untreated | 0 | 1 | 0 | 0 |
| 2 | Saline | 0 | 0 | 0 | 0 |
| 3 | Crocidolite | 100 | 45 | 12 | 27/51 |
| 4 | 1000 | 156 | 59 | 45/50 | |
| 5 | Fibre B | 2000 | 157 | 1 | 3/51 |
| 6 | 5000 | 186 | 9 | 9/51 | |
| 7 | Fibre M | 500 | 44 | 0 | 0 |
| 8 | 2000 | 97 | 1 | 0 | |
| 9 | 5000 | 119 | 1 | 0 | |
| 10 | Fibre O | 500 | 110 | 2 | 0 |
| 11 | 2000 | 133 | 0 | 1/51 | |
| 12 | 5000 | 151 | 1 | 0 | |
| 13 | Fibre P | 500 | 128 | 0 | 0 |
| 14 | 2000 | 140 | 2 | 4/51 | |
| 15 | 5000 | 172 | 6 | 8/51 | |
| 16 | Fibre V | 500 | 117 | 4 | 2/51 |
| 17 | 2000 | 141 | 8 | 1/50 | |
| 18 | 5000 | 143 | 23 | 14/51 |
a Total # of events: sum of incidence at each abdominal organ for each animal
In the publication “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, several studies on carcinogenicity conducted with man-made vitreous fibres were presented and evaluated. These studies include human carcinogenicity case-control and cohort studies, animal experiments on carcinogenicity as well as deposition and retention studies, fibre biopersistence and in vitro dissolution studies.
For all MMVFs considered by the IARC Working Group in 2001, there is inadequate evidence for carcinogenicity in humans on the basis of epidemiological information. The final evaluations of these products thus depended on the animal carcinogenicity data. Table below shows the overall evaluations by the 2001 IARC Monograph Working Groups of the carcinogenic hazard to humans from exposure to man-made mineral (vitreous) fibres, namely mineral wool fibres made of glass, rock/stone or slag.
| Fibre type | Humans | Animals | Overall classification |
| Glass wool | - | - | - |
| Insulation glass wool | Inadequate | Limited | 3 |
| Rock/stone wool | Inadequate | Limited | 3 |
| Slag wool | Inadequate | Limited | 3 |
Overall, MMVFs made of glass, rock/stone and slag wool are classified as Group 3 ( ‘not classifiable as to its carcinogenicity to humans’) substances.
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
Carcinogenicity: via inhalation route
Link to relevant study records
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1998-2000
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations.
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- This study included one exposure level of the substance at 30 mg/m3 and a negative control group exposed to filtered air. The exposure duration was 6 hours/day, 5 days/week for 2 years with a subsequent postexposure period lasting approximately until 20% suvival in the control group.
- GLP compliance:
- yes
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- - Source: Charles River Laboratory, Raleigh, NC
- Age at study initiation: 7-8 weeks at delivery
- Weight at study initiation: approx. 180g at delivery
- Fasting period before study: no data
- Housing: individually or in groups of two
- Diet (e.g. ad libitum):ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: no data
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3°C
- Humidity (%): 30-70%
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12 - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Remarks:
- Nose-only flow-past technique
- Vehicle:
- clean air
- Remarks:
- filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Flow-past exposure chamber. Animals were confined separately in restraint tubes positioned radially at several levels of a vetical aerosol supplytube.
- Method of conditioning air: Electron charge neutralization with a Ni-63 line source.
- System of generating particulates/aerosols: The RCC fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber and oxygen concetrations were all monitored. - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Gravimetric concentration (mg/m3), WHO Fibers (fibers/cm3) and Fibers L>20µm (fibers/cm3) were monitored throughout the entire exposure period of two years.
- Duration of treatment / exposure:
- 6 hours/day, 5 days/week for 2 years with a subsequent postexposure period lasting approximately until 20% survival in the control group.
- Frequency of treatment:
- 6 hours/day, 5 days/week for 2 years
- Post exposure period:
- Until approximately 20% survival in the filtered air control group.
- Remarks:
- Doses / Concentrations:
30 mg/m3
Basis:
other: gravimetric concentration - No. of animals per sex per dose:
- 107
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: The gravimetric concentration of 30 mg/m3 was selected to obtain a fiber concentration of at least 259 WHO fibers/cm3 throughout the exposure period and for being comparable to other studies.
- Positive control:
- No positive control group entered in the study.
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes: clinical signs, morbidity and mortality
- Time schedule: Daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily
BODY WEIGHT: Yes
- Time schedule for examinations: Once a week during the first 13 wk, then every 2 wk.
NECROPSY was performed on all animals
- Sacrifice and pathology:
- Scheduled sacrifices after 3, 6, 12, 18 and 24 months of 5 animals per time-point.
- Statistics:
- Fischer's exact test, one-sided, for the incidence of broncho-alveolar hyperplasia, bronco-alveolar adenomas, and bronco-alveolar carcinomas in rats at risk for tumor formation. Dunnett test based on pooled variance for lung and body weights.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Histopathological findings: neoplastic:
- no effects observed
- Relevance of carcinogenic effects / potential:
- MMVF note Q fibres showed minimal collagen deposition, similar to what could be expected for any biologically inert dust at present exposure level. It is concluded that MMVF note Q fibres did not show a carcinogenic potential neither in the lungs nor in pleura.
- Dose descriptor:
- NOAEC
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: No statistically significant findings of broncho-alveolar hyperplasia, adenomas or carcinomas.
- Remarks on result:
- other: Effect type: carcinogenicity (migrated information)
- Conclusions:
- MMVF note Q fibres were not carcinogenic in the rat and induced only minimal collagen deposition in the lungs.
- Executive summary:
This is a comparable to guideline study with no deviations. Furthermore, it was published in a peer-reviewed scientific journal and details on the test materials and experimental design are very well documented. The objective of the study was to assess potential pathogenic and/or oncogenic effects of chronic inhalation exposure to stone wool fibers in rats.
107 male Fischer 344 rats were exposed 6 h/day, 5 days/week for 2 years to MMVF note Q fibres at 30 mg/m3 by nose-only inhalation of a well-characterized test atmosphere. The study showed that the MMVF note Q fibres possess neither fibrogenic nor carcinogenic potentials in the rat.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Methods of Sachsse et al. (1976); Hesterberg et al. (1991); Bernstein et al. (1993) and Cannon et al. (1983) were followed.
- GLP compliance:
- yes
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC.
- Age at study initiation: 6 weeks
- Housing: Polycarbonate cages
- Diet (e.g. ad libitum): Pelleted standard Kliba 343 rat maintenance diet
- Water (e.g. ad libitum): Filtered fresh water
- Acclimation period: 2 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+-3 oC
- Humidity (%): 30-70%
- Air changes (per hr): 20 air changes/hr
- Photoperiod (hrs dark / hrs light): 12-hr light/dark - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Vehicle:
- clean air
- Remarks:
- Filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Hazelton 2000 chamber
- Source and rate of air:
- System of generating particulates/aerosols:Research and Consulting Company, Geneva, fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber: 22+-3 oC, 30-70%, -20mm H2O
- Air change rate: 20 air change/hr
- Method of particle size determination: WHO Monograph 4 (WHO, 1985)
TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: yes - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Aerosol samples were collected on Gelman membrane filters in the same location as the animal exposure port. Fiber mass concentrations were determined once during pretest, and at least four times per week during the 2 year exposure period. To assure the uniformity of exposure the fiber concentrations were monitored continuously using a RAS (GCA Corp.) light scattering monitor.
Filter sampling was undertaken for each dose group. Samples were collected on Millipore filters, placed between glass slides, and clarified for counting.
Lung Burden Analysis
At necropsy the accessory lobe of the lung from each animal was removed and frozen. Diameter measurements and determination of the number of fibers recovered from the lungs were made at 5000X in a minimum of 20 fields or 200 fiber ends on either a JOEL T 300 SEM or a JOEL 840 SEM equipped with a Videoplan Image Analysis System according to the method outlined in WHO Monograph 4 for measuring airborne man-made mineral fibers (WHO, 1985) by scanning electron microscopy.
During preexposure trials and once every three months thereafter, MMVF note Q fibres' aerosols at each exposure concentration were captured on filters for determination of fiber length and diameter. - Duration of treatment / exposure:
- 24 months
- Frequency of treatment:
- 6 hr/day, 5 days/week
- Post exposure period:
- Until approximately 20% survival in the control group (30 months).
- Remarks:
- Doses / Concentrations:
3, 16, and 30 mg/m3
Basis:
nominal conc. - No. of animals per sex per dose:
- 140 (only male rats were used)
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: To allow comparison with concurrent studies
- Rationale for animal assignment (if not random): Random
- Rationale for selecting satellite groups: No data
- Post-exposure recovery period in satellite groups: 6 months
- Section schedule rationale (if not random): Random - Positive control:
- No
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once a week during the first 13 weeks and at least once a month thereafter.
BODY WEIGHT: Yes
- Time schedule for examinations: Once a week during the first 13 weeks and at least once a month thereafter.
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION: No data
OPHTHALMOSCOPIC EXAMINATION: No data
HAEMATOLOGY: No data
CLINICAL CHEMISTRY: No data
URINALYSIS: No data
NEUROBEHAVIOURAL EXAMINATION: No data
OTHER: - Sacrifice and pathology:
- Sceduled sacrifices were performed: 3 animals after 3 and 6 moths exposure and 6 animals after 12, 18 and 24 moths exposure.
GROSS PATHOLOGY: No
HISTOPATHOLOGY: Yes
Wagner Pathology Grading Scale was used:
Cellular Change
Normal 1 No lesion
Minimal 2 Macrophage response
Mild 3 Bronchioloization, inflammation, fibrosis
Minimal 4 Minimal
Mild 5 Linking of fibrosis
Moderate 6 Consolidation
Severe 7 Marked fibrosis and consolidation
8 Complete obstruction of most airways - Other examinations:
- No data
- Statistics:
- Pairwise comparison of tumor incidence between exposure groups were made using Fisher’s exact test, and tests for trend were made using an exact algorithm for the Cochran-Armitage test. All tests of significance were two-tailed, with no formal adjustment for multiple comparisons. The Student t-test was used for comparisons of the physical characteristics of the fibers.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- not specified
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not specified
- Haematological findings:
- not specified
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not specified
- Behaviour (functional findings):
- not specified
- Organ weight findings including organ / body weight ratios:
- not specified
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
-
HISTOPATHOLOGY: NON-NEOPLASTIC
There was no evidence of treatment-related interstitial lung fibrosis or pleural fibrosis at any time point in the study. Exposure to the substance was associated with nonspecific inflammatory response (macrophage response) in the lungs that did not appear to progress after 6-12 months of exposure. These cellular changes are reversible and are similar to the effects observed after inhalation of an inert dust. No lung fibrosis was observed.
HISTOPATHOLOGY: NEOPLASTIC (if applicable)
Exposure resulted in no mesotheliomas and no statistically significant increase in lung tumor incidence when compared to that of negative control group.
BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant body weight changes or excess mortality during the 2 years of exposure to the substance (data not shown). - Relevance of carcinogenic effects / potential:
- The study showed that 24 months inhalation exposure to MMVF note Q fibres (up to 30 mg/m3) did not induce lung fibrosis, mesothelioma and lung tumours as compared to the control animals.
- Dose descriptor:
- NOAEC
- Effect level:
- > 3 - <= 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: Lung burden of the substance after 3-24 months exposure to: 30 mg/m3 (3.72-5.03 fibers/mg dry lung x 10^3), 16 mg/m3 (2.09-3.46 fibers/mg dry lung x 10^3) and 3 mg/m3 (0.35-0.62 fibers/mg dry lung x 10^3), respectively
- Remarks on result:
- not determinable
- Remarks:
- no NOAEC identified. Effect type:other: lung burden (migrated information)
- Dose descriptor:
- NOEC
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: see 'Remark'
- Remarks on result:
- other: Effect type: toxicity (migrated information)
- Dose descriptor:
- NOAEL
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: No evidence of treatment-related interstitial lung fibrosis or pleural fibrosos. No biologically or statistically significant increase of lung tumor incidence.
- Remarks on result:
- other: Effect type: carcinogenicity (migrated information)
- Conclusions:
- The study shows that MMVF note Q fibres do not possess a potential for fibrotic or neoplastic changes in the lungs in rats.
- Executive summary:
This is a comparable to guideline study with no deviations. Furthermore, it was published in a peer-reviewed scientific journal and details on the test materials and experimental design are very well documented. The purpose of the study was to determine the chronic biological effects in Fischer 344 rats of inhaled size-separated respirable fractions of the substance. Rats were exposed either to the substance or to the filtered air (negative control) using nose-only inhalation chambers, 6 hr/day, 5 days/week, for 24 months to the concentrations of 3, 16 and 30 mg/m3. Exposure to the substance was associated with a nonspecific inflammatory (macrophage) response in the lungs that did not appear to progress after 6-12 months of exposure. No lung fibrosis was observed in the substance exposed animals, and the exposure resulted in no mesothelioma and no statistically significant increase in lung tumour incidence.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations.
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Methods and procedures of Hesterberg et al. (1998), Bernstein et al. (1995), Cannon et al. (1983), Law et al. (1990), Mast et al. (1995), McConnell et al. (1984) and Zoitos et al. (1997) were followed.
- GLP compliance:
- not specified
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River, Raleigh, NC)
- Housing: individually
- Diet (e.g. ad libitum): pelleted standard Kliba 343 ad libitum.
- Water (e.g. ad libitum): ad libitum.
- Acclimation period: acclimatized under laboratory conditions for at least 14 days prior to use
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3 °C
- Humidity (%): 30 to 70% relative humidity
- Photoperiod (hrs dark / hrs light): 12-h light/dark cycle - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Vehicle:
- clean air
- Remarks:
- filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: according to the method of Bernstein et al. (1995).
- Method of holding animals in test chamber: animals were confined separately in glass tubes positioned radially around the flow-past, nose-only exposure chamber (Cannon et al., 1983).
- Source and rate of air: 6h/day, 5days/week, for 2 years
- System of generating particulates/aerosols: RCC fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber: 22±3 °C, 30 to 70% relative humidity
- Method of particle size determination: Scanning electron microscopy (SEM, either a JEOL T 300 SEM or JEOL 840 SEM)
TEST ATMOSPHERE
- Brief description of analytical method used:
Numbers of fibers/mL in each of the aerosols and in the filtered air were determined at least once per week during the first 3 months and once ever 2 wks thereafter. Briefly, aerosol particles were collected on Gelman filters and were resuspended in filtered distilled water and collected onto Millipore filters (0.2-mm pore size). Millipore filters were mounted on a glass microscope slide and clarified with acetone, and fibers were counted on a Bausch and Lomb Balpan Phase Contrast microscope at a magnification of 4003. World Health Organization Monograph 4 counting rules were used for counting synthetic vitreous fibers/cc. Aerosol fiber dimensions were analyzed at least once during pretest, once per week during the first 4 weeks and once every 4 weeks thereafter. SVF aerosol fiber diameters were analyzed using scanning electron microscopy (SEM, either a JEOL T 300 SEM or JEOL 840 SEM) and lengths were analyzed using optical microscopy. Samples of aerosol were captured onto filters in the nose-port of an exposure chamber and stored until analysis (approximately 7 days) in sealed glass bottles containing 8% sodium azide/distilled water. At the time of analysis, to retain all fibers, each filter was washed into its bottle, the filter was ashed, and the ash was mixed back into the suspension. An aliquot was filtered through a 0.2-mm Nuclepore membrane, the membrane was dried, and either clarified on a glass microscope slide for optical length measurement or applied to a stub and gold coated for SEM. Diameter and length of aerosol fibers were measured in a minimum of 100 fibers or 20 fields; diameters were measured at 50003 and lengths were measured at 15003.
- Samples taken from breathing zone: yes, collected on Gelman membrane filters (No. 64515, Gelman Ltd., pore size 0.45 mm) - Analytical verification of doses or concentrations:
- yes
- Duration of treatment / exposure:
- 2 years
- Frequency of treatment:
- 6 h/day, 5 days/week, 2 years
- Post exposure period:
- 23-week exposure-free recovery period
- Remarks:
- Doses / Concentrations:
30 mg/m3
Basis:
nominal conc. - No. of animals per sex per dose:
- 140
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: The target aerosol concentration, 30 mg/m3 (approximately 180 WHO fibers/cc), was chosen as the maximum dose. Previously reported studies indicate that exposure concentrations higher than this can overload lung clearance mechanisms and cause respiratory effects that are not specific to the fiber composition
- Positive control:
- Filtered air.
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All animals were examined for clinical signs of toxicity before the start and after the completion of each exposure day and at least once on nonexposure days.
DETAILED CLINICAL OBSERVATIONS: No data
BODY WEIGHT: Yes
- Time schedule for examinations: Body weights of all animals were monitored weekly during the study period.
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: No
CLINICAL CHEMISTRY: No
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No - Sacrifice and pathology:
- Necropsy was performed on three to six animals immediately after 13, 26, 39, 52, 78, and 104 weeks of exposure and after various post exposure recovery periods.
GROSS PATHOLOGY: No
HISTOPATHOLOGY: Yes - Other examinations:
- - Lung burden analyses: Inhaled fibers were recovered from the right accessory lobe of the lung and were analyzed.
- Statistics:
- Dunnett test based on pooled variance (on organ and body weight results).
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Description (incidence and severity):
- Body weights of Note Q MMVF-exposed animals tended to be 2 to 3% greater than air controls; these differences occasionally reached statistical significance (Dunnett test based on pooled variance, 1% level; data not shown in paper).
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- Irritation (cellularity and inflammation)
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
- Pulmonary changes induced by Note Q MMVF fibres were limited to irritation (cellularity and inflammation), and they did not induce fibrosis or neoplasms.
- Relevance of carcinogenic effects / potential:
- The study showed that 24 months inhalation exposure to MMVF note Q fibres (30 mg/m3) did not induce lung fibrosis, mesothelioma or lung tumours as compared to the control animals, and only minimal lung cellularity that reversed after exposure was terminated.
- Dose descriptor:
- NOAEC
- Effect level:
- ca. 30 mg/m³ air (analytical)
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: histopathology
- Remarks on result:
- other:
- Remarks:
- Effect type: other: Irritation (cellularity and inflammation) (migrated information)
- Conclusions:
- MMVF note Q fibres are neither fibrogenic nor tumourigenic and induced only minimal lung cellularity that reversed after exposure was terminated.
- Executive summary:
The effects of long-term inhalation of MMVF note Q fibres were studied in rats. Of primary concern was the importance of biopersistence as a mechanism of fibre toxicity. Male Fischer rats were exposed to fibre aerosol by nose-only inhalation for 6h/day, 5 days/week for 2 years. The fibre concentration was ~30 mg/m3. MMVF note Q fibres were neither fibrogenic nor tumourigenic and induced only minimal lung cellularity that reversed after exposure was terminated.
- Endpoint:
- carcinogenicity, other
- Remarks:
- Intraperitoneal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- - Principle of test:
Long-term intraperitoneal carcinogenicity test in rats
- Parameters analysed / observed: mortality, morbidity, clinical signs, body weight, presence of palpable masses, ascites fluid, detailed macroscopic post-mortem observation of organs or tissues - GLP compliance:
- yes
- Remarks:
- The study was performed in compliance with the Good Laboratory Practice Regulations (Council Directive 87/18/EEC of 18 December 1986) and the EEC Animal Health Regulation (Council Directive 86/609/EEC of 24 November 1986).
- Specific details on test material used for the study:
- SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: The soluble insulation wools (i.e. fibres B, M, O, P, V) were produced by Saint Gobain SA, Paris, and the crocidolite was provided by Johns Manville Corporation (Mountain Technical Center, Denver, CO).
The following Note Q MMVFs were tested: fibre B (glass wool), fibre M (insulation glass wool), fibre O (silicate stone wool), fibre P (insulation glass wool), fibre V (insulation glass wool) - Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River, France
- Age at study initiation: 8 weeks old
- Weight at study initiation: 209 g
- Housing: housed in a barrier rodent unit under the same conditions as described by Lambre et al., 1998 (Inhal Toxicol 10:995-1021). - Route of administration:
- intraperitoneal
- Vehicle:
- other: saline
- Details on exposure:
- The test substance was administered by intraperitoneal injection in a volume of 2.5 ml saline/injection animal. The injections were performed in the left part of the abdomen (to avoid trauma to the liver), approximately half-way between the xiphoid appendix and genitalia. The rat was maintained manually by a technician in an almost vertical position with the skin in tension. The needle connected to the syringe was inserted by a second technician, perpendicularly to the skin, and then the suspension of fibers was injected gently. A plastic syringe (Terumo, 2-ml syringe, Luer, actual capacity 2.5 ml) fitted with a single-use metal needle (Terumo, Neolus needle, Luer, 20G × 1, 0.9 × 25 mm in first instance, or 18G × 1.5, 1.2 × 40 mm if problems of plugging were encountered) was used. The injections were performed at 1-week intervals without anaesthesia for 2, 8, or 20 times, depending upon the total dose that was to be injected.
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The control of the actual quantities of test substances injected was performed during the course of administration for all groups except the two
negative control groups, using sham injections made into a glass vial. This procedure was performed for each test substance during the course of the 1st, 7th, 14th, and 20th series of injections, and the samples were analysed either gravimetrically or by scanning electron microscopy (SEM) if the weighing results were too disperse. - Duration of treatment / exposure:
- For Note Q MMVFs: Weekly injection with 2 (amounting to 500 x 10^6 fibres), 8 (amounting to 2000 x 10^6 fibres), 20 (amounting to 5000 x 10^6 fibres) injections
For crocidolite: a single injection of 100×10^6 or 1000 × 10^6 - Frequency of treatment:
- Weekly for Note Q MMVFs
Single injection for crocidolite - Post exposure period:
- The study was terminated after 123 wk of observation following the start of exposure, when the survival rate in both negative control groups
reached 20%. - Dose / conc.:
- 500 000 000 other: WHO fibers
- Remarks:
- Tested with fibres M, O, P and V
- Dose / conc.:
- 2 000 000 000 other: WHO fibers
- Remarks:
- Tested with fibres B, M, O, P and V
- Dose / conc.:
- 5 000 000 000 other: WHO fibers
- Remarks:
- Tested with fibres B, M, O, P and V
- No. of animals per sex per dose:
- 51 females per group
- Control animals:
- yes, concurrent no treatment
- yes, concurrent vehicle
- Details on study design:
- - Short description of test conditions:
Eighteen experimental groups, each comprising 51 female rats of the Wistar strain, Crl (WI) BR (Charles River, Saint-Aubin lès Elbeuf, France), were used as follows:
• one group received no injection and acted as an absolute negative control group;
• one group received 20 injections of saline solution and acted as a vehicle negative control group;
• two groups received a single injection of 100 x 10^6 or 1000 x 10^6 fibres of crocidolite and acted as positive control groups;
• two groups received 8 or 20 injections of fibre B (glass wool), to achieve a total of 2000 x 10^6 or 5000 x 10^6 fibres, and acted as ‘soluble-fibre’ reference groups;
• three groups received 2, 8 or 20 injections of fibre M (insulation glass wool) to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre O (stone wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre P (insulation glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre V (insulation glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres.
The intraperitoneal injections were carried out at one week intervals. - Positive control:
- Yes, single injection of 100 × 10^6 or 1000 × 10^6 fibres of crocidolite
- Observations and examinations performed and frequency:
- MORBIDITY AND MORTALITY: Yes
- Time schedule: The animals were checked at least twice a day for mortality or signs of morbidity.
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Each animal was observed for clinical signs at least once a day. From week 27 onward, animals were palpated every 2 week and the date of appearance, size and location, and any changes of observed masses were recorded. Ascites fluid was collected at the beginning of necropsy by puncturing the abdomen. The following parameters were measured: volume; color, fluidity, and transparency by visual assessment, and total proteins in g/L.
BODY WEIGHT: Yes
- Time schedule for examinations: recorded once before allocation of the animals to groups, on the day before the first treatment, at week 2, once a week during the first 13 week of study, and then once every 4 week until the end of the study.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes - Statistics:
- Wilcoxon test for survival data; other statistical tests used but not specified in study
- Clinical signs:
- no effects observed
- Description (incidence and severity):
- The volumetric quantification of ascites fluid from those animals killed at terminal sacrifice showed no significant association with any of the dose or fibre type. The protein content of the fluid ranged from 29 to 44 g/L in 39 samples.
- Dermal irritation (if dermal study):
- not examined
- Mortality:
- mortality observed, treatment-related
- Description (incidence):
- Compared to the saline controls, both doses of crocidolite and the B fibre (5 × 10^9 WHO fibres) groups had a statistically significant reduction in survival. The median survival of this control group was 110 weeks after start of exposure. For the positive control group exposed with 0.5 mg (0.1 x 10^9 WHO fibres) crocidolite the median survival was 97 weeks, and for the B fibre (5 × 10^9 WHO fibres) groups the median survival was 94 weeks.
For all other dose groups of the remaining fibres, there was no statistically significant difference in the survival curves compared to the saline control group. - Body weight and weight changes:
- effects observed, non-treatment-related
- Description (incidence and severity):
- There was no statistically significant differences in mean body weight between the saline-injected control animals and the untreated control animals. Occasional statistically significant differences in mean body weights were observed; however, no systematic differences that could be related to exposure were found. The two control groups are marked, as well as the high dose crocidolite, which had a body weight peak at the 98th week and fibre P high dose had a slightly lower body weight curve.
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- not examined
- Gross pathological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- The most important exposure-related findings were:
1. The palpable masses recorded during the study were observed at a similar incidence and occurrence in both control and treated animals and showed no indication of treatment or dose relationship in size, location, multiplicity, or morphological type.
2. Fibrous adhesions: The previous study had shown that the intraperitoneal injection of ~1 mg resulted in a substantial incidence of fibrotic adhesions compared to the saline control groups. In this study, almost all of the supplementary animals killed at week 21 showed fibrous adhesions. Exposed animals had a high incidence of fibrous adhesions between abdominal organs, most frequently involving liver and diaphragm. The fibrous adhesions were mainly composed of mature collagen fibres, with some occasional fibrocytes. There was an exponential relationship between the total number of adhesions per group and the incidence of mesothelioma when the two crocidolite groups are excluded. For crocidolite, fewer adhesions were noted with a high level of tumours (lower dose: 43 adhesions/27 mesotheliomas; higher dose: 141 adhesions/45 mesotheliomas), suggesting a different mechanism of action for crocidolite as compared to the soluble mineral fibres. The macroscopic findings on the distribution of fibrous adhesions were confirmed by subsequent microscopic examination.
3. Abdominal cavity nodules or masses: The occurrence of nodules and masses above a baseline of approximately six per animal was correlated to the incidence of mesothelioma. Subsequent microscopic examination showed that the fibrotic nodules were composed mainly of fibroblasts, macrophages, and giant cells intermingled with test fibres of variable size and of a variable amount of connective tissue.
4. Incidence of animals with ascites: The incidence of animals with ascites was found to be highly correlated with the incidence of nodules and masses at different sites. The difference between the tested fibres and the insoluble crocidolite in the association of the incidence of nodules and ascites is very clear. - Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- In some animals a chronic inflammatory reaction was observed, which was characterised by a cellular reaction composed mainly of macrophages, fibroblasts and GI cells with variable degree of fibrosis (collagen fibre formation). The highest frequency was observed in the liver. There was a statistically significant association total incidence with the incidence of mesothelioma although with a greater variation at the lower incidences of mesothelioma. Crocidolite appears to have a different association, reinforcing the concept that the tumorigenic mechanism in the intraperitoneal cavity is different for the massive doses of the soluble tested fibres as compared to the lower doses of insoluble crocidolite. Other nonneoplastic findings besides fibrotic and inflammatory reactions unrelated to exposure were observed as would be expected in this age and strain of rats.
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- Mesothelioma was detected with variable incidence and histological subtypes among fibre-treated animals except for the groups treated with fibres M and O (there was one single case in high dose group of O fibre). The microscopic investigation revealed that the mesothelioma developed from the observed fibrotic nodules. The mesotheliomas were always found at sites where macroscopic changes (adhesions, nodules) were seen.
Mesotheliomas were first classified according to their behaviour: (1) Miliary, when the mesothelioma comprised a number of nodules spreading on the peritoneal surface of the abdominal organs; (2) Creeping, when the mesothelioma showed a massive spread on the peritoneal surface and sometimes covering the whole surface of most of the abdominal organs or even infiltrating some organs. Then each category was subdivided according to the microscopic appearance of the cellular elements: (1) epithelial, (2) mesenchymal, and (3) mixed. Only three cases of “true epithelial mesothelioma” were registered.
The malignant tumours defined as abdominal tumours with serosal spread (ATSS) were all diagnosed as primary tumours (from mostly the uterus) with metastasis in the serosa as well as other abdominal organs. These ATSS were of low frequency, between 0 and 4 cases per group and were not considered exposure-related.
Histiocytic sarcoma, found in only a few animals, was not exposure related. This finding was similar to that reported among rats of this sex, age, and strain. The incidence of other neoplastic lesions (except mesothelioma) was not found to be dose related.
The information on neoplastic findings for this high dose study leads to the conclusion that mesothelioma of different histological subtypes is the only tumour type clearly related to treatment. - Details on results:
- This study has demonstrated the following:
1. The intraperitoneal injection especially of very high doses of these fibres causes diffuse fibrosis in the abdominal cavity, which can impair the health status and influences survival in all exposed animals. The most probable mechanism leading to intraperitoneal tumour development is a persistent inflammation accompanied by a nodular fibrotic reaction. A persistent inflammation cell proliferation within these fibrotic nodules appears to be causal to the development of mesothelioma originating from these nodules.
2. The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas.
3. Differences in aetiology were observed between the massive doses of the highly soluble insulation wools when injected directly into the intraperitoneal cavity and the lower doses of the extremely insoluble fibre crocidolite. The variability in this reaction and the impairment of animal health puts into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools.
4. All of the synthetic mineral wool fibre types tested in this study meet the Note Q criteria under CLP Regulation. - Relevance of carcinogenic effects / potential:
- One of the Note Q criteria under CLP Regulation states that a fibre need not be classified as a carcinogen if “an appropriate intraperitoneal test has shown no evidence of excess carcinogenicity.” All of the fibre types tested in this study meet the EC criteria for exoneration (i.e. Note Q). In addition, there is no statistical difference between the results of fibre B and the other synthetic mineral wool fibres tested in this study.
- Conclusions:
- All of the tested mineral wool fibre types in this study meet the Note Q criteria under CLP Regulation (“an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity”).
- Executive summary:
Female Wistar rats (51/group) were exposed intraperitoneally to five soluble mineral wool fibres (fibres B, M, O, P and V), which were injected weekly at total dose levels ranging from 500 to 5000 × 10^6 WHO fibres. There were also negative control (no treatment), vehicle control (saline) and positive control (crocidolite) used in this study. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups).
The tested soluble mineral wool fibres did not produce statistically significant adverse effects on the basis of mortality, clinical signs and body weight. Two of the new insulation wools, fibres M and O, showed no statistically significant tumorigenic response even at the very high dose of 5 × 10^9 WHO fibers injected. Fibres P and V showed a small tumorigenic response in the intraperitoneal cavity similar in magnitude to the B fibre. The response to the soluble insulation fibres was notably different from that of the known carcinogen crocidolite, which produced 53% tumours at a comparatively low dose of 0.1 × 10^9 WHO fibres.
The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas. Differences in aetiology were observed between the massive doses of the highly soluble insulation glass wools when injected directly into the intraperitoneal cavity and the lower doses of the extremely insoluble fiber crocidolite. The variability in this reaction and the impairment of animal health put into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools.
All of the tested mineral wool fibre types in this study meet the Note Q criteria under CLP Regulation (“an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity”).
- Endpoint:
- carcinogenicity, other
- Remarks:
- Intraperitoneal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Principles of method if other than guideline:
- - Principle of test: The long-term intraperitoneal test in rats is generally regarded as a suitable model for evaluating man-made vitreous fibres (MMVFs) for carcinogenic potential because of (1) similarities of responses at the serosal level in the abdominal cavity, compared to those occurring at the pulmonary level and (2) experimental work on natural (particularly various asbestos types) and synthetic fibres, which confirmed a high sensitivity on the basis of induction of mesotheliomas.
- Parameters analysed / observed: mortality, morbidity, clinical signs, body weight, presence of palpable masses, ascites fluid, detailed macroscopic post-mortem observation of organs or tissues - GLP compliance:
- not specified
- Specific details on test material used for the study:
- The following Note Q MMVFs were tested: fibre B (borosilicate glass wool), fibre M (borosilicate glass wool), fibre O (silicate stone wool), fibre P (borosilicate glass wool), fibre V (borosilicate glass wool)
- Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Route of administration:
- intraperitoneal
- Vehicle:
- other: saline
- Details on exposure:
- PREPARATION OF DOSING SOLUTIONS: The volume of the fibre suspension administered was 2.5 ml/injection/animal.
- Analytical verification of doses or concentrations:
- not specified
- Details on analytical verification of doses or concentrations:
- not specified
- Duration of treatment / exposure:
- For Note Q MMVFs: Weekly injection with 2 (amounting to 500 x 10^6 fibres), 8 (amounting to 2000 x 10^6 fibres), 20 (amounting to 5000 x 10^6 fibres) injections
For crocidolite: a single injection of 100×10^6 or 1000 × 10^6 - Frequency of treatment:
- Weekly for Note Q MMVFs
Single injection for crocidolite - Post exposure period:
- 123 weeks of observation
- Dose / conc.:
- 500 000 000 other: WHO fibres
- Remarks:
- Tested with fibres M, O, P and V
- Dose / conc.:
- 2 000 000 000 other: WHO fibres
- Remarks:
- Tested with fibres B, M, O, P and V
- Dose / conc.:
- 5 000 000 000 other: WHO fibres
- Remarks:
- Tested with fibres B, M, O, P and V
- No. of animals per sex per dose:
- 51 female rats per group
- Control animals:
- yes, concurrent no treatment
- yes, concurrent vehicle
- Details on study design:
- - Short description of test conditions:
Eighteen experimental groups, each comprising 51 female rats of the Wistar strain, Crl (WI) BR (Charles River, Saint-Aubin lès Elbeuf, France), were used as follows:
• one group received no injection and acted as an absolute negative control group;
• one group received 20 injections of saline solution and acted as a vehicle negative control group;
• two groups received a single injection of 100 x 10^6 or 1000 x 10^6 fibres of crocidolite and acted as positive control groups;
• two groups received 8 or 20 injections of fibre B (borosilicate glass wool), to achieve a total of 2000 x 10^6 or 5000 x 10^6 fibres, and acted as ‘soluble-fibre’ reference groups;
• three groups received 2, 8 or 20 injections of fibre M (borosilicate glass wool) to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre O (silicate stone wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre P (borosilicate glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre V (borosilicate glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres.
The intraperitoneal injections were carried out at one week intervals. - Positive control:
- Yes, single injection of 100 × 10^6 or 1000 × 10^6 fibres of crocidolite
- Observations and examinations performed and frequency:
- The animals were checked daily for mortality, morbidity and clinical signs. Body weight and presence of palpable masses were recorded at regular intervals. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups). In any decedent or surviving animals, ascites fluid was collected (when present) and analysed. A detailed macroscopic post-mortem observation was carried out. A full range of organs or tissues was sampled. Designated organs were then examined microscopically: organs and tissues of the abdominal cavity, palpable masses and macroscopic lesions. This examination focused on carcinogenic effects, in particular on possible tumours of the abdominal cavity, especially mesotheliomas.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes - Statistics:
- Dunnett's test for body weight
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- - Signs of ascites formation in the abdomen, in the groups injected with crocidolite, fibres B and P (marked), fibre V (moderate) and with fibre O (slight).
- Signs of anaemia in the groups injected with crocidolite and fibre B (all dose-levels). This correlated with the presence of haemorrhagic ascites fluid. - Mortality:
- mortality observed, treatment-related
- Description (incidence):
- - The 20 injections of saline solution produced a slight increase of mortality rate, when compared to the absolute control animals.
- The injection of crocidolite produced a marked increase of mortality at both dose levels.
- The injection of fibres M, O, P and V did not increase the normal mortality rate regardless of the dose level.
- The injection of fibre B produced a slight increase of mortality, but only at the high dose level (i.e. 5000 × 10^6 fibres). - Body weight and weight changes:
- effects observed, non-treatment-related
- Description (incidence and severity):
- - The 20 injections of saline solution did not produce an effect on body weight gain when compared to the absolute control animals.
- The injection of fibres M, O and P produced a slight decrease of body weight gain but only at the high dose level (5000 × 10^6 fibres).
- The injection of fibre V did not produce an effect on body weight gain regardless of the dose level.
According to the key study of Grimm et al., 2002, which is the same study as this one, it was mentioned that "there was no statistically significant differences in mean body weight between the saline-injected control animals and the untreated control animals. Occasional statistically significant differences in mean body weights were observed; however, no systematic differences that could be related to exposure were found." - Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not specified
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not specified
- Organ weight findings including organ / body weight ratios:
- not specified
- Gross pathological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- The macroscopic lesions produced by the injection of fibres were confined to the abdominal cavity.
- There were fibrous adhesions between various abdominal organs in all fibre-injected groups, with a dose-related incidence and severity: for crocidolite (high), fibres B, P and V (moderate), and fibres M and O (low).
- There were nodules or masses on the diaphragm, abdominal wall, adipose tissue and mesentery/ abdominal cavity with a dose-related incidence and severity (similar to fibrous adhesions): for crocidolite (high), fibres B, P and V (moderate), and fibres M and O (low). - Neuropathological findings:
- not specified
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- The non-neoplastic lesions observed at microscopic examination and attributable to the injection of fibres. They were confined to fibrous adhesion between numerous organs in the abdominal cavity in almost all fibre-injected animals (except crocidolite at the low dose level). The severity was dose-related for crocidolite (moderate to marked), fibres B, P and V (slight to moderate), and fibres M and O (minimal to slight). These findings were sometimes associated with chronic peritonitis with fibrotic nodules or hepatocellular necrosis.
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- The neoplastic lesions observed at microscopic examination and attributable to the injection of fibres were limited to mesothelioma in the abdominal cavity.
From this point of view, the following classification can be made:
- no mesothelioma: negative control groups, fibres M and O;
- low occurrence of mesothelioma (4–28% of the animals): fibres B, P and V;
- high occurrence of mesothelioma (53–90% of the animals): crocidolite.
Besides mesothelioma, the tumour profile of the animals was not modified in any group: the nature, incidence and latency of the other neoplastic lesions was similar to what can be expected for animals of this strain and age. - Other effects:
- not specified
- Relevance of carcinogenic effects / potential:
- 1. no mesothelioma: negative control groups, fibres M and O;
2. low or moderate occurrence of mesothelioma (4–28% of the animals): fibres B, P and V. - Conclusions:
- The tested soluble mineral wool fibres (B, M, O, P and V) did not produce notable adverse effects on the basis of mortality, clinical signs and body weight except at high dose levels. Histopathological investigations distinguished the various fibres:
* Fibres M and O did not induce mesotheliomas at tested doses up to 5000 × 10^6 fibres;
* Fibres P and V induced up to 16% and 28%, respectively, of mesotheliomas at the same dose of 5000 x 10^6 fibres and in the same range as for the reference fibre B (18% of animals with mesotheliomas).
* 90% of the crocidolite-treated animals displayed mesotheliomas at a dose level of 1000 × 10^6 fibres.
This interpretation of this study is given more in details in other key study of Grimm et al. (2002), which concluded that all the tested soluble mineral wool fibres fulfilled the Note Q criteria under CLP Regulation (“an appropriate intraperitoneal test has not expressed signs of excessive carcinogenicity"). - Executive summary:
Female Wistar rats (51/group) were exposed intraperitoneally to five soluble mineral wool fibres (fibres B, M, O, P and V), which were injected weekly at total dose levels ranging from 500 to 5000 × 10^6 WHO fibres. There were also negative control (no treatment), vehicle control (saline) and positive control (crocidolite) used in this study. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups).
The tested fibres did not produce notable adverse effects on the basis of mortality, clinical signs and body weight except at high dose levels. Histopathological investigations distinguished the various fibres:
* Fibres M and O did not induce mesotheliomas at tested doses up to 5000 × 10^6 fibres;
* Fibres P and V induced up to 16% and 28%, respectively, of mesotheliomas at the same dose of 5000 x 10^6 fibres and in the same range as for the reference fibre B (18% of animals with mesotheliomas).
* 90% of the crocidolite-treated animals displayed mesotheliomas at a dose level of 1000 × 10^6 fibres.
This interpretation of this study is given more in details in other key study of Grimm et al. (2002), which concluded that all the tested soluble mineral wool fibres fulfilled the Note Q criteria under CLP Regulation (“an appropriate intraperitoneal test has not expressed signs of excessive carcinogenicity").
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- other: IARC monograph
- Adequacy of study:
- supporting study
- Reliability:
- 3 (not reliable)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- This publication evaluates the carcinogenic risks of man-made vitreous fibers in humans with the help of international working groups of experts prepared, critical reviews and evaluations of evidence on the carcinogenicity of a wide range of human exposures.
- GLP compliance:
- no
- Remarks on result:
- not determinable
- Remarks:
- Critical literature review
- Critical effects observed:
- not specified
- Conclusions:
- Based on the presented data in the publication, “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, man-made vitreous fibres made of glass, rock/stone or slag wool are classified as Group 3 (‘not classifiable as to its carcinogenicity to humans’) substances.
- Executive summary:
In the publication “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, several studies on carcinogenicity conducted with MMVFs were evaluated and presented. These studies include human carcinogenicity case-control and cohort studies, animal experiments on carcinogenicity as well as deposition and retention studies, fibre biopersistence and in vitro dissolution studies.
For all MMVFs considered by the IARC Working Group in 2001, there is inadequate evidence for carcinogenicity in humans on the basis of epidemiological information. The final evaluations of these products thus depended on the animal carcinogenicity data. Overall, MMVFs made of glass, rock/stone and slag wool are classified as Group 3 (‘not classifiable as to its carcinogenicity to humans’)substances.
Referenceopen allclose all
Summary incidence of broncho-alveolar hyperplasia, bronco-alveolar adenomas, and bronco-alveolar carcinomas in rats at risk for tumor formation:
Group |
n |
Broncho-alveolar hyperplasia |
Adenoma |
Carcinoma |
Carcinoma + adenoma |
||||
n |
% |
n |
% |
n |
% |
n |
% |
||
MMVF note Q fibres |
107 |
6 |
5.6 |
5 |
4.7 |
0 |
0.0 |
5 |
4.7 |
Control |
107 |
4 |
3.7 |
3 |
2.8 |
1 |
0.9 |
4 |
3.7 |
Note. n, Number of animals "at risk" (defined as the number of animals sacrified at the end of the 12-month exposure period, and the number of animals subsequently found dead or sacrified until the termination of the study, provided that they were exposed for at least 12 months and that their lungs were examined histologically).
Statistical method: Exposed group compared to concurrent control using Fischer's exact test, one-sided. [No statistically significant findings at 5% level].
Average Wagner Scores in rats to filtererd air, or MMVF note Q fibres:
Euthanize/exposure (months) |
Air control |
MMVF note Q fibres |
||
3 mg/m3 |
16 mg/m3 |
30 mg/m3 |
||
Continous exposure |
||||
3/3 |
1.0 |
2.0 |
2.0 |
3.0 |
6/6 |
1.0 |
2.0 |
2.3 |
3.0 |
12/12 |
1.0 |
2.2 |
3.0 |
3.0 |
18/18 |
1.0 |
2.5 |
3.0 |
3.0 |
24/24 |
1.0 |
2.5 |
2.7 |
2.5 |
Recovery |
||||
24/3 |
1.0 |
1.2 |
2.0 |
2.0 |
24/6 |
1.0 |
1.5 |
2.0 |
2.2 |
24/12 |
1.0 |
2.0 |
2.0 |
2.0 |
24/18 |
1.0 |
2.0 |
2.5 |
2.2 |
30/24 c |
1.0 |
2.0 |
2.2 |
2.5 |
c: These animals represent the terminal euthanization which occurred when animal survival was approximately 20%.
Summary of Lung Tumor Findings:
Exposure group |
At risk b |
Adenomas |
Carcinomas |
Total lung tumors |
Mesotheliomas |
Controls |
123 |
3 (2.4%) |
1 (0.8%) |
4 (3.3%) |
0 |
3 mg/m3 |
118 |
3 (2.5%) |
1 (0.9%) |
4 (3.4%) |
0 |
16 mg/m3 |
120 |
6 (5.0%) |
3 (2.5%) |
9 (7.5%) |
0 |
30 mg/m3 |
112 |
3 (2.7%) |
0 |
3 (2.7%) |
0 |
b: Only animals that were exposed to fibers for at least 1 year were considered at risk for induction of neoplasms as this was the earliest time point a neoplastic finding was observed in this series of studies.
Pulmonary and Mesothelial Proliferative Lesions
Exposure |
Nb |
Hyperplasia (bronchioalveolar)a |
Lung cancera |
Mesothelioma (pleural)a |
||
Adenoma |
Carcinoma |
Total lung cancers |
||||
Air |
130 |
5 (3.8) |
2 (1.5) |
0 |
2 (1.5) |
0 |
MMVF note Q fibres |
121 |
6 (4.9) |
1 (0.8) |
1 (0.8) |
3 (1.6) |
0 |
Note.No significant findings.
a Values are the total number of X. Values in parentheses are percentages.
b Number of animals at risk for tumor formation (at-risk defined as surviving until at least the 12-month time point, after first tumor appeared).
Pulmonary Change: Mean Wagner Scorea
Exposure / Recovery (weeks) |
Air control (Exposure only) |
MMVF note Q fibres |
|
Exposure |
Recovery |
||
13/91 |
1.3 |
2.0 |
1.3 |
26/78 |
1.0 |
2.0 |
1.0 |
39/65 |
1.0 |
2.3 |
1.0 |
52/52 |
1.0 |
3.0 |
2.5 |
65/nd |
1.0 |
3.0 |
nd |
78/26 |
1.0 |
3.0 |
2.0 |
104/23 |
1.0 |
2.8 |
2.7 |
For exposure animals, n = 3–6; for 104+23 week time point, n = > 10; for interim recovery groups, n = 2–4 due to decreasing suvival. nd, not done.
a Scores according to Wagner, 1984. Scale: 1, no lesion; 2, macrophage aggregation; 3, cellularity; 4, fibrosis (irreversible); 5, linking fibrosis.
Inflammation and Collagen Deposition in the Lung and Pleura
Exposure / Recovery (weeks) |
Alveolar macrophage aggregation a |
Alveolar bronchiolization a |
Microgranulation a |
Bronchioalveolar collagen a |
Pleural collagen a |
|||||
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
|
13/91 |
1.0 |
1.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
26/78 |
1.3 |
0.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
39/65 |
2.0 |
1.0 |
0.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
52/52 |
2.0 |
1.5 |
1.2 |
0.5 |
0 |
0.5 |
0 |
0 |
0 |
0 |
78/26 |
2.3 |
2.0 |
2.0 |
0 |
2.0 |
0.5 |
0 |
0 |
0 |
0 |
104/23 |
2.1 |
2.1 |
1.0 |
0.8 |
1.2 |
1.5 |
0 |
0 |
0 |
0 |
Note.Level of severity of lesions observed at time points during 2-year exposure period and 6-month recovery period was graded as follows: grade 0, normal; 1, minimal; 2, mild; 3, moderate; 4, marked; 5, massive. Each grade is a mean of 3–10 animals.
a Expos. indicates animals had exposure but not recovery time; recov. indicates animals had exposure + recovery.
Table: Summary of survival rate, body weight and incidence of ascites fluid
| Group | Test material | Dose level (x10^6 WHO fibres) | Median survival (weeks) | Body weight in study week 78 (grams) | Incidence of ascites fluid |
| 1 | Untreated | 0 | 118 | 512 | 0 |
| 2 | Saline | 0 | 113 | 512 | 0 |
| 3 | Crocidolite | 100 | 105 | 498 | 27 |
| 4 | 1000 | 67 | 486 | 49 | |
| 5 | Fibre B | 2000 | 121 | 473* | 6 |
| 6 | 5000 | 100 | 490 | 23 | |
| 7 | Fibre M | 500 | 112 | 495 | 4 |
| 8 | 2000 | 119 | 507 | 3 | |
| 9 | 5000 | 114 | 480 | 6 | |
| 10 | Fibre O | 500 | 104 | 506 | 2 |
| 11 | 2000 | 115 | 498 | 4 | |
| 12 | 5000 | 119 | 486 | 10 | |
| 13 | Fibre P | 500 | 110 | 499 | 1 |
| 14 | 2000 | 120 | 494 | 16 | |
| 15 | 5000 | 112 | 456** | 36 | |
| 16 | Fibre V | 500 | 119 | 488 | 8 |
| 17 | 2000 | 117 | 494 | 7 | |
| 18 | 5000 | 109 | 508 | 27 |
* p < 0.05; p < 0.01 (Dunnett's test).
Table: Summary of microscopic findings
| Group | Test material | Dose level (x10^6 WHO fibres) | Abdominal adhesion (total # of events)a | Chronic peritonitis (total # of events) | Mesotheliomas (# animals affected/# animals examined) |
| 1 | Untreated | 0 | 1 | 0 | 0 |
| 2 | Saline | 0 | 0 | 0 | 0 |
| 3 | Crocidolite | 100 | 45 | 12 | 27/51 |
| 4 | 1000 | 156 | 59 | 45/50 | |
| 5 | Fibre B | 2000 | 157 | 1 | 3/51 |
| 6 | 5000 | 186 | 9 | 9/51 | |
| 7 | Fibre M | 500 | 44 | 0 | 0 |
| 8 | 2000 | 97 | 1 | 0 | |
| 9 | 5000 | 119 | 1 | 0 | |
| 10 | Fibre O | 500 | 110 | 2 | 0 |
| 11 | 2000 | 133 | 0 | 1/51 | |
| 12 | 5000 | 151 | 1 | 0 | |
| 13 | Fibre P | 500 | 128 | 0 | 0 |
| 14 | 2000 | 140 | 2 | 4/51 | |
| 15 | 5000 | 172 | 6 | 8/51 | |
| 16 | Fibre V | 500 | 117 | 4 | 2/51 |
| 17 | 2000 | 141 | 8 | 1/50 | |
| 18 | 5000 | 143 | 23 | 14/51 |
a Total # of events: sum of incidence at each abdominal organ for each animal
In the publication “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, several studies on carcinogenicity conducted with man-made vitreous fibres were presented and evaluated. These studies include human carcinogenicity case-control and cohort studies, animal experiments on carcinogenicity as well as deposition and retention studies, fibre biopersistence and in vitro dissolution studies.
For all MMVFs considered by the IARC Working Group in 2001, there is inadequate evidence for carcinogenicity in humans on the basis of epidemiological information. The final evaluations of these products thus depended on the animal carcinogenicity data. Table below shows the overall evaluations by the 2001 IARC Monograph Working Groups of the carcinogenic hazard to humans from exposure to man-made mineral (vitreous) fibres, namely mineral wool fibres made of glass, rock/stone or slag.
| Fibre type | Humans | Animals | Overall classification |
| Glass wool | - | - | - |
| Insulation glass wool | Inadequate | Limited | 3 |
| Rock/stone wool | Inadequate | Limited | 3 |
| Slag wool | Inadequate | Limited | 3 |
Overall, MMVFs made of glass, rock/stone and slag wool are classified as Group 3 ( ‘not classifiable as to its carcinogenicity to humans’) substances.
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEC
- 30 mg/m³
Carcinogenicity: via dermal route
Link to relevant study records
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1998-2000
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations.
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- This study included one exposure level of the substance at 30 mg/m3 and a negative control group exposed to filtered air. The exposure duration was 6 hours/day, 5 days/week for 2 years with a subsequent postexposure period lasting approximately until 20% suvival in the control group.
- GLP compliance:
- yes
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- - Source: Charles River Laboratory, Raleigh, NC
- Age at study initiation: 7-8 weeks at delivery
- Weight at study initiation: approx. 180g at delivery
- Fasting period before study: no data
- Housing: individually or in groups of two
- Diet (e.g. ad libitum):ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: no data
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3°C
- Humidity (%): 30-70%
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12 - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Remarks:
- Nose-only flow-past technique
- Vehicle:
- clean air
- Remarks:
- filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Flow-past exposure chamber. Animals were confined separately in restraint tubes positioned radially at several levels of a vetical aerosol supplytube.
- Method of conditioning air: Electron charge neutralization with a Ni-63 line source.
- System of generating particulates/aerosols: The RCC fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber and oxygen concetrations were all monitored. - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Gravimetric concentration (mg/m3), WHO Fibers (fibers/cm3) and Fibers L>20µm (fibers/cm3) were monitored throughout the entire exposure period of two years.
- Duration of treatment / exposure:
- 6 hours/day, 5 days/week for 2 years with a subsequent postexposure period lasting approximately until 20% survival in the control group.
- Frequency of treatment:
- 6 hours/day, 5 days/week for 2 years
- Post exposure period:
- Until approximately 20% survival in the filtered air control group.
- Remarks:
- Doses / Concentrations:
30 mg/m3
Basis:
other: gravimetric concentration - No. of animals per sex per dose:
- 107
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: The gravimetric concentration of 30 mg/m3 was selected to obtain a fiber concentration of at least 259 WHO fibers/cm3 throughout the exposure period and for being comparable to other studies.
- Positive control:
- No positive control group entered in the study.
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes: clinical signs, morbidity and mortality
- Time schedule: Daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily
BODY WEIGHT: Yes
- Time schedule for examinations: Once a week during the first 13 wk, then every 2 wk.
NECROPSY was performed on all animals
- Sacrifice and pathology:
- Scheduled sacrifices after 3, 6, 12, 18 and 24 months of 5 animals per time-point.
- Statistics:
- Fischer's exact test, one-sided, for the incidence of broncho-alveolar hyperplasia, bronco-alveolar adenomas, and bronco-alveolar carcinomas in rats at risk for tumor formation. Dunnett test based on pooled variance for lung and body weights.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Histopathological findings: neoplastic:
- no effects observed
- Relevance of carcinogenic effects / potential:
- MMVF note Q fibres showed minimal collagen deposition, similar to what could be expected for any biologically inert dust at present exposure level. It is concluded that MMVF note Q fibres did not show a carcinogenic potential neither in the lungs nor in pleura.
- Dose descriptor:
- NOAEC
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: No statistically significant findings of broncho-alveolar hyperplasia, adenomas or carcinomas.
- Remarks on result:
- other: Effect type: carcinogenicity (migrated information)
- Conclusions:
- MMVF note Q fibres were not carcinogenic in the rat and induced only minimal collagen deposition in the lungs.
- Executive summary:
This is a comparable to guideline study with no deviations. Furthermore, it was published in a peer-reviewed scientific journal and details on the test materials and experimental design are very well documented. The objective of the study was to assess potential pathogenic and/or oncogenic effects of chronic inhalation exposure to stone wool fibers in rats.
107 male Fischer 344 rats were exposed 6 h/day, 5 days/week for 2 years to MMVF note Q fibres at 30 mg/m3 by nose-only inhalation of a well-characterized test atmosphere. The study showed that the MMVF note Q fibres possess neither fibrogenic nor carcinogenic potentials in the rat.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to other study
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Methods of Sachsse et al. (1976); Hesterberg et al. (1991); Bernstein et al. (1993) and Cannon et al. (1983) were followed.
- GLP compliance:
- yes
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC.
- Age at study initiation: 6 weeks
- Housing: Polycarbonate cages
- Diet (e.g. ad libitum): Pelleted standard Kliba 343 rat maintenance diet
- Water (e.g. ad libitum): Filtered fresh water
- Acclimation period: 2 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+-3 oC
- Humidity (%): 30-70%
- Air changes (per hr): 20 air changes/hr
- Photoperiod (hrs dark / hrs light): 12-hr light/dark - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Vehicle:
- clean air
- Remarks:
- Filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Hazelton 2000 chamber
- Source and rate of air:
- System of generating particulates/aerosols:Research and Consulting Company, Geneva, fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber: 22+-3 oC, 30-70%, -20mm H2O
- Air change rate: 20 air change/hr
- Method of particle size determination: WHO Monograph 4 (WHO, 1985)
TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: yes - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Aerosol samples were collected on Gelman membrane filters in the same location as the animal exposure port. Fiber mass concentrations were determined once during pretest, and at least four times per week during the 2 year exposure period. To assure the uniformity of exposure the fiber concentrations were monitored continuously using a RAS (GCA Corp.) light scattering monitor.
Filter sampling was undertaken for each dose group. Samples were collected on Millipore filters, placed between glass slides, and clarified for counting.
Lung Burden Analysis
At necropsy the accessory lobe of the lung from each animal was removed and frozen. Diameter measurements and determination of the number of fibers recovered from the lungs were made at 5000X in a minimum of 20 fields or 200 fiber ends on either a JOEL T 300 SEM or a JOEL 840 SEM equipped with a Videoplan Image Analysis System according to the method outlined in WHO Monograph 4 for measuring airborne man-made mineral fibers (WHO, 1985) by scanning electron microscopy.
During preexposure trials and once every three months thereafter, MMVF note Q fibres' aerosols at each exposure concentration were captured on filters for determination of fiber length and diameter. - Duration of treatment / exposure:
- 24 months
- Frequency of treatment:
- 6 hr/day, 5 days/week
- Post exposure period:
- Until approximately 20% survival in the control group (30 months).
- Remarks:
- Doses / Concentrations:
3, 16, and 30 mg/m3
Basis:
nominal conc. - No. of animals per sex per dose:
- 140 (only male rats were used)
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: To allow comparison with concurrent studies
- Rationale for animal assignment (if not random): Random
- Rationale for selecting satellite groups: No data
- Post-exposure recovery period in satellite groups: 6 months
- Section schedule rationale (if not random): Random - Positive control:
- No
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once a week during the first 13 weeks and at least once a month thereafter.
BODY WEIGHT: Yes
- Time schedule for examinations: Once a week during the first 13 weeks and at least once a month thereafter.
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION: No data
OPHTHALMOSCOPIC EXAMINATION: No data
HAEMATOLOGY: No data
CLINICAL CHEMISTRY: No data
URINALYSIS: No data
NEUROBEHAVIOURAL EXAMINATION: No data
OTHER: - Sacrifice and pathology:
- Sceduled sacrifices were performed: 3 animals after 3 and 6 moths exposure and 6 animals after 12, 18 and 24 moths exposure.
GROSS PATHOLOGY: No
HISTOPATHOLOGY: Yes
Wagner Pathology Grading Scale was used:
Cellular Change
Normal 1 No lesion
Minimal 2 Macrophage response
Mild 3 Bronchioloization, inflammation, fibrosis
Minimal 4 Minimal
Mild 5 Linking of fibrosis
Moderate 6 Consolidation
Severe 7 Marked fibrosis and consolidation
8 Complete obstruction of most airways - Other examinations:
- No data
- Statistics:
- Pairwise comparison of tumor incidence between exposure groups were made using Fisher’s exact test, and tests for trend were made using an exact algorithm for the Cochran-Armitage test. All tests of significance were two-tailed, with no formal adjustment for multiple comparisons. The Student t-test was used for comparisons of the physical characteristics of the fibers.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- not specified
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not specified
- Haematological findings:
- not specified
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not specified
- Behaviour (functional findings):
- not specified
- Organ weight findings including organ / body weight ratios:
- not specified
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
-
HISTOPATHOLOGY: NON-NEOPLASTIC
There was no evidence of treatment-related interstitial lung fibrosis or pleural fibrosis at any time point in the study. Exposure to the substance was associated with nonspecific inflammatory response (macrophage response) in the lungs that did not appear to progress after 6-12 months of exposure. These cellular changes are reversible and are similar to the effects observed after inhalation of an inert dust. No lung fibrosis was observed.
HISTOPATHOLOGY: NEOPLASTIC (if applicable)
Exposure resulted in no mesotheliomas and no statistically significant increase in lung tumor incidence when compared to that of negative control group.
BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant body weight changes or excess mortality during the 2 years of exposure to the substance (data not shown). - Relevance of carcinogenic effects / potential:
- The study showed that 24 months inhalation exposure to MMVF note Q fibres (up to 30 mg/m3) did not induce lung fibrosis, mesothelioma and lung tumours as compared to the control animals.
- Dose descriptor:
- NOAEC
- Effect level:
- > 3 - <= 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: Lung burden of the substance after 3-24 months exposure to: 30 mg/m3 (3.72-5.03 fibers/mg dry lung x 10^3), 16 mg/m3 (2.09-3.46 fibers/mg dry lung x 10^3) and 3 mg/m3 (0.35-0.62 fibers/mg dry lung x 10^3), respectively
- Remarks on result:
- not determinable
- Remarks:
- no NOAEC identified. Effect type:other: lung burden (migrated information)
- Dose descriptor:
- NOEC
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: see 'Remark'
- Remarks on result:
- other: Effect type: toxicity (migrated information)
- Dose descriptor:
- NOAEL
- Effect level:
- 30 mg/m³ air
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: No evidence of treatment-related interstitial lung fibrosis or pleural fibrosos. No biologically or statistically significant increase of lung tumor incidence.
- Remarks on result:
- other: Effect type: carcinogenicity (migrated information)
- Conclusions:
- The study shows that MMVF note Q fibres do not possess a potential for fibrotic or neoplastic changes in the lungs in rats.
- Executive summary:
This is a comparable to guideline study with no deviations. Furthermore, it was published in a peer-reviewed scientific journal and details on the test materials and experimental design are very well documented. The purpose of the study was to determine the chronic biological effects in Fischer 344 rats of inhaled size-separated respirable fractions of the substance. Rats were exposed either to the substance or to the filtered air (negative control) using nose-only inhalation chambers, 6 hr/day, 5 days/week, for 24 months to the concentrations of 3, 16 and 30 mg/m3. Exposure to the substance was associated with a nonspecific inflammatory (macrophage) response in the lungs that did not appear to progress after 6-12 months of exposure. No lung fibrosis was observed in the substance exposed animals, and the exposure resulted in no mesothelioma and no statistically significant increase in lung tumour incidence.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Comparable to guideline study. No deviations.
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Methods and procedures of Hesterberg et al. (1998), Bernstein et al. (1995), Cannon et al. (1983), Law et al. (1990), Mast et al. (1995), McConnell et al. (1984) and Zoitos et al. (1997) were followed.
- GLP compliance:
- not specified
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River, Raleigh, NC)
- Housing: individually
- Diet (e.g. ad libitum): pelleted standard Kliba 343 ad libitum.
- Water (e.g. ad libitum): ad libitum.
- Acclimation period: acclimatized under laboratory conditions for at least 14 days prior to use
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3 °C
- Humidity (%): 30 to 70% relative humidity
- Photoperiod (hrs dark / hrs light): 12-h light/dark cycle - Route of administration:
- inhalation: aerosol
- Type of inhalation exposure (if applicable):
- nose only
- Vehicle:
- clean air
- Remarks:
- filtered air
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: according to the method of Bernstein et al. (1995).
- Method of holding animals in test chamber: animals were confined separately in glass tubes positioned radially around the flow-past, nose-only exposure chamber (Cannon et al., 1983).
- Source and rate of air: 6h/day, 5days/week, for 2 years
- System of generating particulates/aerosols: RCC fiber aerosol generation system.
- Temperature, humidity, pressure in air chamber: 22±3 °C, 30 to 70% relative humidity
- Method of particle size determination: Scanning electron microscopy (SEM, either a JEOL T 300 SEM or JEOL 840 SEM)
TEST ATMOSPHERE
- Brief description of analytical method used:
Numbers of fibers/mL in each of the aerosols and in the filtered air were determined at least once per week during the first 3 months and once ever 2 wks thereafter. Briefly, aerosol particles were collected on Gelman filters and were resuspended in filtered distilled water and collected onto Millipore filters (0.2-mm pore size). Millipore filters were mounted on a glass microscope slide and clarified with acetone, and fibers were counted on a Bausch and Lomb Balpan Phase Contrast microscope at a magnification of 4003. World Health Organization Monograph 4 counting rules were used for counting synthetic vitreous fibers/cc. Aerosol fiber dimensions were analyzed at least once during pretest, once per week during the first 4 weeks and once every 4 weeks thereafter. SVF aerosol fiber diameters were analyzed using scanning electron microscopy (SEM, either a JEOL T 300 SEM or JEOL 840 SEM) and lengths were analyzed using optical microscopy. Samples of aerosol were captured onto filters in the nose-port of an exposure chamber and stored until analysis (approximately 7 days) in sealed glass bottles containing 8% sodium azide/distilled water. At the time of analysis, to retain all fibers, each filter was washed into its bottle, the filter was ashed, and the ash was mixed back into the suspension. An aliquot was filtered through a 0.2-mm Nuclepore membrane, the membrane was dried, and either clarified on a glass microscope slide for optical length measurement or applied to a stub and gold coated for SEM. Diameter and length of aerosol fibers were measured in a minimum of 100 fibers or 20 fields; diameters were measured at 50003 and lengths were measured at 15003.
- Samples taken from breathing zone: yes, collected on Gelman membrane filters (No. 64515, Gelman Ltd., pore size 0.45 mm) - Analytical verification of doses or concentrations:
- yes
- Duration of treatment / exposure:
- 2 years
- Frequency of treatment:
- 6 h/day, 5 days/week, 2 years
- Post exposure period:
- 23-week exposure-free recovery period
- Remarks:
- Doses / Concentrations:
30 mg/m3
Basis:
nominal conc. - No. of animals per sex per dose:
- 140
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: The target aerosol concentration, 30 mg/m3 (approximately 180 WHO fibers/cc), was chosen as the maximum dose. Previously reported studies indicate that exposure concentrations higher than this can overload lung clearance mechanisms and cause respiratory effects that are not specific to the fiber composition
- Positive control:
- Filtered air.
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All animals were examined for clinical signs of toxicity before the start and after the completion of each exposure day and at least once on nonexposure days.
DETAILED CLINICAL OBSERVATIONS: No data
BODY WEIGHT: Yes
- Time schedule for examinations: Body weights of all animals were monitored weekly during the study period.
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: No
CLINICAL CHEMISTRY: No
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No - Sacrifice and pathology:
- Necropsy was performed on three to six animals immediately after 13, 26, 39, 52, 78, and 104 weeks of exposure and after various post exposure recovery periods.
GROSS PATHOLOGY: No
HISTOPATHOLOGY: Yes - Other examinations:
- - Lung burden analyses: Inhaled fibers were recovered from the right accessory lobe of the lung and were analyzed.
- Statistics:
- Dunnett test based on pooled variance (on organ and body weight results).
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Description (incidence and severity):
- Body weights of Note Q MMVF-exposed animals tended to be 2 to 3% greater than air controls; these differences occasionally reached statistical significance (Dunnett test based on pooled variance, 1% level; data not shown in paper).
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Gross pathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- Irritation (cellularity and inflammation)
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
- Pulmonary changes induced by Note Q MMVF fibres were limited to irritation (cellularity and inflammation), and they did not induce fibrosis or neoplasms.
- Relevance of carcinogenic effects / potential:
- The study showed that 24 months inhalation exposure to MMVF note Q fibres (30 mg/m3) did not induce lung fibrosis, mesothelioma or lung tumours as compared to the control animals, and only minimal lung cellularity that reversed after exposure was terminated.
- Dose descriptor:
- NOAEC
- Effect level:
- ca. 30 mg/m³ air (analytical)
- Based on:
- test mat.
- Sex:
- male
- Basis for effect level:
- other: histopathology
- Remarks on result:
- other:
- Remarks:
- Effect type: other: Irritation (cellularity and inflammation) (migrated information)
- Conclusions:
- MMVF note Q fibres are neither fibrogenic nor tumourigenic and induced only minimal lung cellularity that reversed after exposure was terminated.
- Executive summary:
The effects of long-term inhalation of MMVF note Q fibres were studied in rats. Of primary concern was the importance of biopersistence as a mechanism of fibre toxicity. Male Fischer rats were exposed to fibre aerosol by nose-only inhalation for 6h/day, 5 days/week for 2 years. The fibre concentration was ~30 mg/m3. MMVF note Q fibres were neither fibrogenic nor tumourigenic and induced only minimal lung cellularity that reversed after exposure was terminated.
- Endpoint:
- carcinogenicity, other
- Remarks:
- Intraperitoneal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- - Principle of test:
Long-term intraperitoneal carcinogenicity test in rats
- Parameters analysed / observed: mortality, morbidity, clinical signs, body weight, presence of palpable masses, ascites fluid, detailed macroscopic post-mortem observation of organs or tissues - GLP compliance:
- yes
- Remarks:
- The study was performed in compliance with the Good Laboratory Practice Regulations (Council Directive 87/18/EEC of 18 December 1986) and the EEC Animal Health Regulation (Council Directive 86/609/EEC of 24 November 1986).
- Specific details on test material used for the study:
- SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: The soluble insulation wools (i.e. fibres B, M, O, P, V) were produced by Saint Gobain SA, Paris, and the crocidolite was provided by Johns Manville Corporation (Mountain Technical Center, Denver, CO).
The following Note Q MMVFs were tested: fibre B (glass wool), fibre M (insulation glass wool), fibre O (silicate stone wool), fibre P (insulation glass wool), fibre V (insulation glass wool) - Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River, France
- Age at study initiation: 8 weeks old
- Weight at study initiation: 209 g
- Housing: housed in a barrier rodent unit under the same conditions as described by Lambre et al., 1998 (Inhal Toxicol 10:995-1021). - Route of administration:
- intraperitoneal
- Vehicle:
- other: saline
- Details on exposure:
- The test substance was administered by intraperitoneal injection in a volume of 2.5 ml saline/injection animal. The injections were performed in the left part of the abdomen (to avoid trauma to the liver), approximately half-way between the xiphoid appendix and genitalia. The rat was maintained manually by a technician in an almost vertical position with the skin in tension. The needle connected to the syringe was inserted by a second technician, perpendicularly to the skin, and then the suspension of fibers was injected gently. A plastic syringe (Terumo, 2-ml syringe, Luer, actual capacity 2.5 ml) fitted with a single-use metal needle (Terumo, Neolus needle, Luer, 20G × 1, 0.9 × 25 mm in first instance, or 18G × 1.5, 1.2 × 40 mm if problems of plugging were encountered) was used. The injections were performed at 1-week intervals without anaesthesia for 2, 8, or 20 times, depending upon the total dose that was to be injected.
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The control of the actual quantities of test substances injected was performed during the course of administration for all groups except the two
negative control groups, using sham injections made into a glass vial. This procedure was performed for each test substance during the course of the 1st, 7th, 14th, and 20th series of injections, and the samples were analysed either gravimetrically or by scanning electron microscopy (SEM) if the weighing results were too disperse. - Duration of treatment / exposure:
- For Note Q MMVFs: Weekly injection with 2 (amounting to 500 x 10^6 fibres), 8 (amounting to 2000 x 10^6 fibres), 20 (amounting to 5000 x 10^6 fibres) injections
For crocidolite: a single injection of 100×10^6 or 1000 × 10^6 - Frequency of treatment:
- Weekly for Note Q MMVFs
Single injection for crocidolite - Post exposure period:
- The study was terminated after 123 wk of observation following the start of exposure, when the survival rate in both negative control groups
reached 20%. - Dose / conc.:
- 500 000 000 other: WHO fibers
- Remarks:
- Tested with fibres M, O, P and V
- Dose / conc.:
- 2 000 000 000 other: WHO fibers
- Remarks:
- Tested with fibres B, M, O, P and V
- Dose / conc.:
- 5 000 000 000 other: WHO fibers
- Remarks:
- Tested with fibres B, M, O, P and V
- No. of animals per sex per dose:
- 51 females per group
- Control animals:
- yes, concurrent no treatment
- yes, concurrent vehicle
- Details on study design:
- - Short description of test conditions:
Eighteen experimental groups, each comprising 51 female rats of the Wistar strain, Crl (WI) BR (Charles River, Saint-Aubin lès Elbeuf, France), were used as follows:
• one group received no injection and acted as an absolute negative control group;
• one group received 20 injections of saline solution and acted as a vehicle negative control group;
• two groups received a single injection of 100 x 10^6 or 1000 x 10^6 fibres of crocidolite and acted as positive control groups;
• two groups received 8 or 20 injections of fibre B (glass wool), to achieve a total of 2000 x 10^6 or 5000 x 10^6 fibres, and acted as ‘soluble-fibre’ reference groups;
• three groups received 2, 8 or 20 injections of fibre M (insulation glass wool) to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre O (stone wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre P (insulation glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre V (insulation glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres.
The intraperitoneal injections were carried out at one week intervals. - Positive control:
- Yes, single injection of 100 × 10^6 or 1000 × 10^6 fibres of crocidolite
- Observations and examinations performed and frequency:
- MORBIDITY AND MORTALITY: Yes
- Time schedule: The animals were checked at least twice a day for mortality or signs of morbidity.
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Each animal was observed for clinical signs at least once a day. From week 27 onward, animals were palpated every 2 week and the date of appearance, size and location, and any changes of observed masses were recorded. Ascites fluid was collected at the beginning of necropsy by puncturing the abdomen. The following parameters were measured: volume; color, fluidity, and transparency by visual assessment, and total proteins in g/L.
BODY WEIGHT: Yes
- Time schedule for examinations: recorded once before allocation of the animals to groups, on the day before the first treatment, at week 2, once a week during the first 13 week of study, and then once every 4 week until the end of the study.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes - Statistics:
- Wilcoxon test for survival data; other statistical tests used but not specified in study
- Clinical signs:
- no effects observed
- Description (incidence and severity):
- The volumetric quantification of ascites fluid from those animals killed at terminal sacrifice showed no significant association with any of the dose or fibre type. The protein content of the fluid ranged from 29 to 44 g/L in 39 samples.
- Dermal irritation (if dermal study):
- not examined
- Mortality:
- mortality observed, treatment-related
- Description (incidence):
- Compared to the saline controls, both doses of crocidolite and the B fibre (5 × 10^9 WHO fibres) groups had a statistically significant reduction in survival. The median survival of this control group was 110 weeks after start of exposure. For the positive control group exposed with 0.5 mg (0.1 x 10^9 WHO fibres) crocidolite the median survival was 97 weeks, and for the B fibre (5 × 10^9 WHO fibres) groups the median survival was 94 weeks.
For all other dose groups of the remaining fibres, there was no statistically significant difference in the survival curves compared to the saline control group. - Body weight and weight changes:
- effects observed, non-treatment-related
- Description (incidence and severity):
- There was no statistically significant differences in mean body weight between the saline-injected control animals and the untreated control animals. Occasional statistically significant differences in mean body weights were observed; however, no systematic differences that could be related to exposure were found. The two control groups are marked, as well as the high dose crocidolite, which had a body weight peak at the 98th week and fibre P high dose had a slightly lower body weight curve.
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not examined
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- not examined
- Gross pathological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- The most important exposure-related findings were:
1. The palpable masses recorded during the study were observed at a similar incidence and occurrence in both control and treated animals and showed no indication of treatment or dose relationship in size, location, multiplicity, or morphological type.
2. Fibrous adhesions: The previous study had shown that the intraperitoneal injection of ~1 mg resulted in a substantial incidence of fibrotic adhesions compared to the saline control groups. In this study, almost all of the supplementary animals killed at week 21 showed fibrous adhesions. Exposed animals had a high incidence of fibrous adhesions between abdominal organs, most frequently involving liver and diaphragm. The fibrous adhesions were mainly composed of mature collagen fibres, with some occasional fibrocytes. There was an exponential relationship between the total number of adhesions per group and the incidence of mesothelioma when the two crocidolite groups are excluded. For crocidolite, fewer adhesions were noted with a high level of tumours (lower dose: 43 adhesions/27 mesotheliomas; higher dose: 141 adhesions/45 mesotheliomas), suggesting a different mechanism of action for crocidolite as compared to the soluble mineral fibres. The macroscopic findings on the distribution of fibrous adhesions were confirmed by subsequent microscopic examination.
3. Abdominal cavity nodules or masses: The occurrence of nodules and masses above a baseline of approximately six per animal was correlated to the incidence of mesothelioma. Subsequent microscopic examination showed that the fibrotic nodules were composed mainly of fibroblasts, macrophages, and giant cells intermingled with test fibres of variable size and of a variable amount of connective tissue.
4. Incidence of animals with ascites: The incidence of animals with ascites was found to be highly correlated with the incidence of nodules and masses at different sites. The difference between the tested fibres and the insoluble crocidolite in the association of the incidence of nodules and ascites is very clear. - Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- In some animals a chronic inflammatory reaction was observed, which was characterised by a cellular reaction composed mainly of macrophages, fibroblasts and GI cells with variable degree of fibrosis (collagen fibre formation). The highest frequency was observed in the liver. There was a statistically significant association total incidence with the incidence of mesothelioma although with a greater variation at the lower incidences of mesothelioma. Crocidolite appears to have a different association, reinforcing the concept that the tumorigenic mechanism in the intraperitoneal cavity is different for the massive doses of the soluble tested fibres as compared to the lower doses of insoluble crocidolite. Other nonneoplastic findings besides fibrotic and inflammatory reactions unrelated to exposure were observed as would be expected in this age and strain of rats.
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- Mesothelioma was detected with variable incidence and histological subtypes among fibre-treated animals except for the groups treated with fibres M and O (there was one single case in high dose group of O fibre). The microscopic investigation revealed that the mesothelioma developed from the observed fibrotic nodules. The mesotheliomas were always found at sites where macroscopic changes (adhesions, nodules) were seen.
Mesotheliomas were first classified according to their behaviour: (1) Miliary, when the mesothelioma comprised a number of nodules spreading on the peritoneal surface of the abdominal organs; (2) Creeping, when the mesothelioma showed a massive spread on the peritoneal surface and sometimes covering the whole surface of most of the abdominal organs or even infiltrating some organs. Then each category was subdivided according to the microscopic appearance of the cellular elements: (1) epithelial, (2) mesenchymal, and (3) mixed. Only three cases of “true epithelial mesothelioma” were registered.
The malignant tumours defined as abdominal tumours with serosal spread (ATSS) were all diagnosed as primary tumours (from mostly the uterus) with metastasis in the serosa as well as other abdominal organs. These ATSS were of low frequency, between 0 and 4 cases per group and were not considered exposure-related.
Histiocytic sarcoma, found in only a few animals, was not exposure related. This finding was similar to that reported among rats of this sex, age, and strain. The incidence of other neoplastic lesions (except mesothelioma) was not found to be dose related.
The information on neoplastic findings for this high dose study leads to the conclusion that mesothelioma of different histological subtypes is the only tumour type clearly related to treatment. - Details on results:
- This study has demonstrated the following:
1. The intraperitoneal injection especially of very high doses of these fibres causes diffuse fibrosis in the abdominal cavity, which can impair the health status and influences survival in all exposed animals. The most probable mechanism leading to intraperitoneal tumour development is a persistent inflammation accompanied by a nodular fibrotic reaction. A persistent inflammation cell proliferation within these fibrotic nodules appears to be causal to the development of mesothelioma originating from these nodules.
2. The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas.
3. Differences in aetiology were observed between the massive doses of the highly soluble insulation wools when injected directly into the intraperitoneal cavity and the lower doses of the extremely insoluble fibre crocidolite. The variability in this reaction and the impairment of animal health puts into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools.
4. All of the synthetic mineral wool fibre types tested in this study meet the Note Q criteria under CLP Regulation. - Relevance of carcinogenic effects / potential:
- One of the Note Q criteria under CLP Regulation states that a fibre need not be classified as a carcinogen if “an appropriate intraperitoneal test has shown no evidence of excess carcinogenicity.” All of the fibre types tested in this study meet the EC criteria for exoneration (i.e. Note Q). In addition, there is no statistical difference between the results of fibre B and the other synthetic mineral wool fibres tested in this study.
- Conclusions:
- All of the tested mineral wool fibre types in this study meet the Note Q criteria under CLP Regulation (“an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity”).
- Executive summary:
Female Wistar rats (51/group) were exposed intraperitoneally to five soluble mineral wool fibres (fibres B, M, O, P and V), which were injected weekly at total dose levels ranging from 500 to 5000 × 10^6 WHO fibres. There were also negative control (no treatment), vehicle control (saline) and positive control (crocidolite) used in this study. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups).
The tested soluble mineral wool fibres did not produce statistically significant adverse effects on the basis of mortality, clinical signs and body weight. Two of the new insulation wools, fibres M and O, showed no statistically significant tumorigenic response even at the very high dose of 5 × 10^9 WHO fibers injected. Fibres P and V showed a small tumorigenic response in the intraperitoneal cavity similar in magnitude to the B fibre. The response to the soluble insulation fibres was notably different from that of the known carcinogen crocidolite, which produced 53% tumours at a comparatively low dose of 0.1 × 10^9 WHO fibres.
The incidence of mesothelioma was found to be highly correlated to the incidence of intra-abdominal nodules and masses at different sites. The incidence of abdominal nodules and masses was highly correlated to the number of animals with ascites. The incidence of chronic peritonitis with fibrotic nodules at different organs also correlated with the incidence of mesotheliomas. Differences in aetiology were observed between the massive doses of the highly soluble insulation glass wools when injected directly into the intraperitoneal cavity and the lower doses of the extremely insoluble fiber crocidolite. The variability in this reaction and the impairment of animal health put into question the value of these massive doses in evaluating the carcinogenic response of soluble insulation wools.
All of the tested mineral wool fibre types in this study meet the Note Q criteria under CLP Regulation (“an appropriate intra-peritoneal test has not expressed signs of excessive carcinogenicity”).
- Endpoint:
- carcinogenicity, other
- Remarks:
- Intraperitoneal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Principles of method if other than guideline:
- - Principle of test: The long-term intraperitoneal test in rats is generally regarded as a suitable model for evaluating man-made vitreous fibres (MMVFs) for carcinogenic potential because of (1) similarities of responses at the serosal level in the abdominal cavity, compared to those occurring at the pulmonary level and (2) experimental work on natural (particularly various asbestos types) and synthetic fibres, which confirmed a high sensitivity on the basis of induction of mesotheliomas.
- Parameters analysed / observed: mortality, morbidity, clinical signs, body weight, presence of palpable masses, ascites fluid, detailed macroscopic post-mortem observation of organs or tissues - GLP compliance:
- not specified
- Specific details on test material used for the study:
- The following Note Q MMVFs were tested: fibre B (borosilicate glass wool), fibre M (borosilicate glass wool), fibre O (silicate stone wool), fibre P (borosilicate glass wool), fibre V (borosilicate glass wool)
- Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Route of administration:
- intraperitoneal
- Vehicle:
- other: saline
- Details on exposure:
- PREPARATION OF DOSING SOLUTIONS: The volume of the fibre suspension administered was 2.5 ml/injection/animal.
- Analytical verification of doses or concentrations:
- not specified
- Details on analytical verification of doses or concentrations:
- not specified
- Duration of treatment / exposure:
- For Note Q MMVFs: Weekly injection with 2 (amounting to 500 x 10^6 fibres), 8 (amounting to 2000 x 10^6 fibres), 20 (amounting to 5000 x 10^6 fibres) injections
For crocidolite: a single injection of 100×10^6 or 1000 × 10^6 - Frequency of treatment:
- Weekly for Note Q MMVFs
Single injection for crocidolite - Post exposure period:
- 123 weeks of observation
- Dose / conc.:
- 500 000 000 other: WHO fibres
- Remarks:
- Tested with fibres M, O, P and V
- Dose / conc.:
- 2 000 000 000 other: WHO fibres
- Remarks:
- Tested with fibres B, M, O, P and V
- Dose / conc.:
- 5 000 000 000 other: WHO fibres
- Remarks:
- Tested with fibres B, M, O, P and V
- No. of animals per sex per dose:
- 51 female rats per group
- Control animals:
- yes, concurrent no treatment
- yes, concurrent vehicle
- Details on study design:
- - Short description of test conditions:
Eighteen experimental groups, each comprising 51 female rats of the Wistar strain, Crl (WI) BR (Charles River, Saint-Aubin lès Elbeuf, France), were used as follows:
• one group received no injection and acted as an absolute negative control group;
• one group received 20 injections of saline solution and acted as a vehicle negative control group;
• two groups received a single injection of 100 x 10^6 or 1000 x 10^6 fibres of crocidolite and acted as positive control groups;
• two groups received 8 or 20 injections of fibre B (borosilicate glass wool), to achieve a total of 2000 x 10^6 or 5000 x 10^6 fibres, and acted as ‘soluble-fibre’ reference groups;
• three groups received 2, 8 or 20 injections of fibre M (borosilicate glass wool) to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre O (silicate stone wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre P (borosilicate glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres;
• three groups received 2, 8 or 20 injections of fibre V (borosilicate glass wool), to achieve a total of 500 x 10^6, 2000 x 10^6 or 5000 x 10^6 fibres.
The intraperitoneal injections were carried out at one week intervals. - Positive control:
- Yes, single injection of 100 × 10^6 or 1000 × 10^6 fibres of crocidolite
- Observations and examinations performed and frequency:
- The animals were checked daily for mortality, morbidity and clinical signs. Body weight and presence of palpable masses were recorded at regular intervals. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups). In any decedent or surviving animals, ascites fluid was collected (when present) and analysed. A detailed macroscopic post-mortem observation was carried out. A full range of organs or tissues was sampled. Designated organs were then examined microscopically: organs and tissues of the abdominal cavity, palpable masses and macroscopic lesions. This examination focused on carcinogenic effects, in particular on possible tumours of the abdominal cavity, especially mesotheliomas.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes - Statistics:
- Dunnett's test for body weight
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- - Signs of ascites formation in the abdomen, in the groups injected with crocidolite, fibres B and P (marked), fibre V (moderate) and with fibre O (slight).
- Signs of anaemia in the groups injected with crocidolite and fibre B (all dose-levels). This correlated with the presence of haemorrhagic ascites fluid. - Mortality:
- mortality observed, treatment-related
- Description (incidence):
- - The 20 injections of saline solution produced a slight increase of mortality rate, when compared to the absolute control animals.
- The injection of crocidolite produced a marked increase of mortality at both dose levels.
- The injection of fibres M, O, P and V did not increase the normal mortality rate regardless of the dose level.
- The injection of fibre B produced a slight increase of mortality, but only at the high dose level (i.e. 5000 × 10^6 fibres). - Body weight and weight changes:
- effects observed, non-treatment-related
- Description (incidence and severity):
- - The 20 injections of saline solution did not produce an effect on body weight gain when compared to the absolute control animals.
- The injection of fibres M, O and P produced a slight decrease of body weight gain but only at the high dose level (5000 × 10^6 fibres).
- The injection of fibre V did not produce an effect on body weight gain regardless of the dose level.
According to the key study of Grimm et al., 2002, which is the same study as this one, it was mentioned that "there was no statistically significant differences in mean body weight between the saline-injected control animals and the untreated control animals. Occasional statistically significant differences in mean body weights were observed; however, no systematic differences that could be related to exposure were found." - Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- not specified
- Clinical biochemistry findings:
- not specified
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not specified
- Organ weight findings including organ / body weight ratios:
- not specified
- Gross pathological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- The macroscopic lesions produced by the injection of fibres were confined to the abdominal cavity.
- There were fibrous adhesions between various abdominal organs in all fibre-injected groups, with a dose-related incidence and severity: for crocidolite (high), fibres B, P and V (moderate), and fibres M and O (low).
- There were nodules or masses on the diaphragm, abdominal wall, adipose tissue and mesentery/ abdominal cavity with a dose-related incidence and severity (similar to fibrous adhesions): for crocidolite (high), fibres B, P and V (moderate), and fibres M and O (low). - Neuropathological findings:
- not specified
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- The non-neoplastic lesions observed at microscopic examination and attributable to the injection of fibres. They were confined to fibrous adhesion between numerous organs in the abdominal cavity in almost all fibre-injected animals (except crocidolite at the low dose level). The severity was dose-related for crocidolite (moderate to marked), fibres B, P and V (slight to moderate), and fibres M and O (minimal to slight). These findings were sometimes associated with chronic peritonitis with fibrotic nodules or hepatocellular necrosis.
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- The neoplastic lesions observed at microscopic examination and attributable to the injection of fibres were limited to mesothelioma in the abdominal cavity.
From this point of view, the following classification can be made:
- no mesothelioma: negative control groups, fibres M and O;
- low occurrence of mesothelioma (4–28% of the animals): fibres B, P and V;
- high occurrence of mesothelioma (53–90% of the animals): crocidolite.
Besides mesothelioma, the tumour profile of the animals was not modified in any group: the nature, incidence and latency of the other neoplastic lesions was similar to what can be expected for animals of this strain and age. - Other effects:
- not specified
- Relevance of carcinogenic effects / potential:
- 1. no mesothelioma: negative control groups, fibres M and O;
2. low or moderate occurrence of mesothelioma (4–28% of the animals): fibres B, P and V. - Conclusions:
- The tested soluble mineral wool fibres (B, M, O, P and V) did not produce notable adverse effects on the basis of mortality, clinical signs and body weight except at high dose levels. Histopathological investigations distinguished the various fibres:
* Fibres M and O did not induce mesotheliomas at tested doses up to 5000 × 10^6 fibres;
* Fibres P and V induced up to 16% and 28%, respectively, of mesotheliomas at the same dose of 5000 x 10^6 fibres and in the same range as for the reference fibre B (18% of animals with mesotheliomas).
* 90% of the crocidolite-treated animals displayed mesotheliomas at a dose level of 1000 × 10^6 fibres.
This interpretation of this study is given more in details in other key study of Grimm et al. (2002), which concluded that all the tested soluble mineral wool fibres fulfilled the Note Q criteria under CLP Regulation (“an appropriate intraperitoneal test has not expressed signs of excessive carcinogenicity"). - Executive summary:
Female Wistar rats (51/group) were exposed intraperitoneally to five soluble mineral wool fibres (fibres B, M, O, P and V), which were injected weekly at total dose levels ranging from 500 to 5000 × 10^6 WHO fibres. There were also negative control (no treatment), vehicle control (saline) and positive control (crocidolite) used in this study. The study was stopped after 123 weeks of observation (when the mortality rate was 80% in the negative control groups).
The tested fibres did not produce notable adverse effects on the basis of mortality, clinical signs and body weight except at high dose levels. Histopathological investigations distinguished the various fibres:
* Fibres M and O did not induce mesotheliomas at tested doses up to 5000 × 10^6 fibres;
* Fibres P and V induced up to 16% and 28%, respectively, of mesotheliomas at the same dose of 5000 x 10^6 fibres and in the same range as for the reference fibre B (18% of animals with mesotheliomas).
* 90% of the crocidolite-treated animals displayed mesotheliomas at a dose level of 1000 × 10^6 fibres.
This interpretation of this study is given more in details in other key study of Grimm et al. (2002), which concluded that all the tested soluble mineral wool fibres fulfilled the Note Q criteria under CLP Regulation (“an appropriate intraperitoneal test has not expressed signs of excessive carcinogenicity").
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- other: IARC monograph
- Adequacy of study:
- supporting study
- Reliability:
- 3 (not reliable)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- This publication evaluates the carcinogenic risks of man-made vitreous fibers in humans with the help of international working groups of experts prepared, critical reviews and evaluations of evidence on the carcinogenicity of a wide range of human exposures.
- GLP compliance:
- no
- Remarks on result:
- not determinable
- Remarks:
- Critical literature review
- Critical effects observed:
- not specified
- Conclusions:
- Based on the presented data in the publication, “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, man-made vitreous fibres made of glass, rock/stone or slag wool are classified as Group 3 (‘not classifiable as to its carcinogenicity to humans’) substances.
- Executive summary:
In the publication “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, several studies on carcinogenicity conducted with MMVFs were evaluated and presented. These studies include human carcinogenicity case-control and cohort studies, animal experiments on carcinogenicity as well as deposition and retention studies, fibre biopersistence and in vitro dissolution studies.
For all MMVFs considered by the IARC Working Group in 2001, there is inadequate evidence for carcinogenicity in humans on the basis of epidemiological information. The final evaluations of these products thus depended on the animal carcinogenicity data. Overall, MMVFs made of glass, rock/stone and slag wool are classified as Group 3 (‘not classifiable as to its carcinogenicity to humans’)substances.
Referenceopen allclose all
Summary incidence of broncho-alveolar hyperplasia, bronco-alveolar adenomas, and bronco-alveolar carcinomas in rats at risk for tumor formation:
Group |
n |
Broncho-alveolar hyperplasia |
Adenoma |
Carcinoma |
Carcinoma + adenoma |
||||
n |
% |
n |
% |
n |
% |
n |
% |
||
MMVF note Q fibres |
107 |
6 |
5.6 |
5 |
4.7 |
0 |
0.0 |
5 |
4.7 |
Control |
107 |
4 |
3.7 |
3 |
2.8 |
1 |
0.9 |
4 |
3.7 |
Note. n, Number of animals "at risk" (defined as the number of animals sacrified at the end of the 12-month exposure period, and the number of animals subsequently found dead or sacrified until the termination of the study, provided that they were exposed for at least 12 months and that their lungs were examined histologically).
Statistical method: Exposed group compared to concurrent control using Fischer's exact test, one-sided. [No statistically significant findings at 5% level].
Average Wagner Scores in rats to filtererd air, or MMVF note Q fibres:
Euthanize/exposure (months) |
Air control |
MMVF note Q fibres |
||
3 mg/m3 |
16 mg/m3 |
30 mg/m3 |
||
Continous exposure |
||||
3/3 |
1.0 |
2.0 |
2.0 |
3.0 |
6/6 |
1.0 |
2.0 |
2.3 |
3.0 |
12/12 |
1.0 |
2.2 |
3.0 |
3.0 |
18/18 |
1.0 |
2.5 |
3.0 |
3.0 |
24/24 |
1.0 |
2.5 |
2.7 |
2.5 |
Recovery |
||||
24/3 |
1.0 |
1.2 |
2.0 |
2.0 |
24/6 |
1.0 |
1.5 |
2.0 |
2.2 |
24/12 |
1.0 |
2.0 |
2.0 |
2.0 |
24/18 |
1.0 |
2.0 |
2.5 |
2.2 |
30/24 c |
1.0 |
2.0 |
2.2 |
2.5 |
c: These animals represent the terminal euthanization which occurred when animal survival was approximately 20%.
Summary of Lung Tumor Findings:
Exposure group |
At risk b |
Adenomas |
Carcinomas |
Total lung tumors |
Mesotheliomas |
Controls |
123 |
3 (2.4%) |
1 (0.8%) |
4 (3.3%) |
0 |
3 mg/m3 |
118 |
3 (2.5%) |
1 (0.9%) |
4 (3.4%) |
0 |
16 mg/m3 |
120 |
6 (5.0%) |
3 (2.5%) |
9 (7.5%) |
0 |
30 mg/m3 |
112 |
3 (2.7%) |
0 |
3 (2.7%) |
0 |
b: Only animals that were exposed to fibers for at least 1 year were considered at risk for induction of neoplasms as this was the earliest time point a neoplastic finding was observed in this series of studies.
Pulmonary and Mesothelial Proliferative Lesions
Exposure |
Nb |
Hyperplasia (bronchioalveolar)a |
Lung cancera |
Mesothelioma (pleural)a |
||
Adenoma |
Carcinoma |
Total lung cancers |
||||
Air |
130 |
5 (3.8) |
2 (1.5) |
0 |
2 (1.5) |
0 |
MMVF note Q fibres |
121 |
6 (4.9) |
1 (0.8) |
1 (0.8) |
3 (1.6) |
0 |
Note.No significant findings.
a Values are the total number of X. Values in parentheses are percentages.
b Number of animals at risk for tumor formation (at-risk defined as surviving until at least the 12-month time point, after first tumor appeared).
Pulmonary Change: Mean Wagner Scorea
Exposure / Recovery (weeks) |
Air control (Exposure only) |
MMVF note Q fibres |
|
Exposure |
Recovery |
||
13/91 |
1.3 |
2.0 |
1.3 |
26/78 |
1.0 |
2.0 |
1.0 |
39/65 |
1.0 |
2.3 |
1.0 |
52/52 |
1.0 |
3.0 |
2.5 |
65/nd |
1.0 |
3.0 |
nd |
78/26 |
1.0 |
3.0 |
2.0 |
104/23 |
1.0 |
2.8 |
2.7 |
For exposure animals, n = 3–6; for 104+23 week time point, n = > 10; for interim recovery groups, n = 2–4 due to decreasing suvival. nd, not done.
a Scores according to Wagner, 1984. Scale: 1, no lesion; 2, macrophage aggregation; 3, cellularity; 4, fibrosis (irreversible); 5, linking fibrosis.
Inflammation and Collagen Deposition in the Lung and Pleura
Exposure / Recovery (weeks) |
Alveolar macrophage aggregation a |
Alveolar bronchiolization a |
Microgranulation a |
Bronchioalveolar collagen a |
Pleural collagen a |
|||||
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
Expos. |
+ Recov. |
|
13/91 |
1.0 |
1.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
26/78 |
1.3 |
0.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
39/65 |
2.0 |
1.0 |
0.3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
52/52 |
2.0 |
1.5 |
1.2 |
0.5 |
0 |
0.5 |
0 |
0 |
0 |
0 |
78/26 |
2.3 |
2.0 |
2.0 |
0 |
2.0 |
0.5 |
0 |
0 |
0 |
0 |
104/23 |
2.1 |
2.1 |
1.0 |
0.8 |
1.2 |
1.5 |
0 |
0 |
0 |
0 |
Note.Level of severity of lesions observed at time points during 2-year exposure period and 6-month recovery period was graded as follows: grade 0, normal; 1, minimal; 2, mild; 3, moderate; 4, marked; 5, massive. Each grade is a mean of 3–10 animals.
a Expos. indicates animals had exposure but not recovery time; recov. indicates animals had exposure + recovery.
Table: Summary of survival rate, body weight and incidence of ascites fluid
| Group | Test material | Dose level (x10^6 WHO fibres) | Median survival (weeks) | Body weight in study week 78 (grams) | Incidence of ascites fluid |
| 1 | Untreated | 0 | 118 | 512 | 0 |
| 2 | Saline | 0 | 113 | 512 | 0 |
| 3 | Crocidolite | 100 | 105 | 498 | 27 |
| 4 | 1000 | 67 | 486 | 49 | |
| 5 | Fibre B | 2000 | 121 | 473* | 6 |
| 6 | 5000 | 100 | 490 | 23 | |
| 7 | Fibre M | 500 | 112 | 495 | 4 |
| 8 | 2000 | 119 | 507 | 3 | |
| 9 | 5000 | 114 | 480 | 6 | |
| 10 | Fibre O | 500 | 104 | 506 | 2 |
| 11 | 2000 | 115 | 498 | 4 | |
| 12 | 5000 | 119 | 486 | 10 | |
| 13 | Fibre P | 500 | 110 | 499 | 1 |
| 14 | 2000 | 120 | 494 | 16 | |
| 15 | 5000 | 112 | 456** | 36 | |
| 16 | Fibre V | 500 | 119 | 488 | 8 |
| 17 | 2000 | 117 | 494 | 7 | |
| 18 | 5000 | 109 | 508 | 27 |
* p < 0.05; p < 0.01 (Dunnett's test).
Table: Summary of microscopic findings
| Group | Test material | Dose level (x10^6 WHO fibres) | Abdominal adhesion (total # of events)a | Chronic peritonitis (total # of events) | Mesotheliomas (# animals affected/# animals examined) |
| 1 | Untreated | 0 | 1 | 0 | 0 |
| 2 | Saline | 0 | 0 | 0 | 0 |
| 3 | Crocidolite | 100 | 45 | 12 | 27/51 |
| 4 | 1000 | 156 | 59 | 45/50 | |
| 5 | Fibre B | 2000 | 157 | 1 | 3/51 |
| 6 | 5000 | 186 | 9 | 9/51 | |
| 7 | Fibre M | 500 | 44 | 0 | 0 |
| 8 | 2000 | 97 | 1 | 0 | |
| 9 | 5000 | 119 | 1 | 0 | |
| 10 | Fibre O | 500 | 110 | 2 | 0 |
| 11 | 2000 | 133 | 0 | 1/51 | |
| 12 | 5000 | 151 | 1 | 0 | |
| 13 | Fibre P | 500 | 128 | 0 | 0 |
| 14 | 2000 | 140 | 2 | 4/51 | |
| 15 | 5000 | 172 | 6 | 8/51 | |
| 16 | Fibre V | 500 | 117 | 4 | 2/51 |
| 17 | 2000 | 141 | 8 | 1/50 | |
| 18 | 5000 | 143 | 23 | 14/51 |
a Total # of events: sum of incidence at each abdominal organ for each animal
In the publication “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 81 – Man-made Vitreous Fibers”, several studies on carcinogenicity conducted with man-made vitreous fibres were presented and evaluated. These studies include human carcinogenicity case-control and cohort studies, animal experiments on carcinogenicity as well as deposition and retention studies, fibre biopersistence and in vitro dissolution studies.
For all MMVFs considered by the IARC Working Group in 2001, there is inadequate evidence for carcinogenicity in humans on the basis of epidemiological information. The final evaluations of these products thus depended on the animal carcinogenicity data. Table below shows the overall evaluations by the 2001 IARC Monograph Working Groups of the carcinogenic hazard to humans from exposure to man-made mineral (vitreous) fibres, namely mineral wool fibres made of glass, rock/stone or slag.
| Fibre type | Humans | Animals | Overall classification |
| Glass wool | - | - | - |
| Insulation glass wool | Inadequate | Limited | 3 |
| Rock/stone wool | Inadequate | Limited | 3 |
| Slag wool | Inadequate | Limited | 3 |
Overall, MMVFs made of glass, rock/stone and slag wool are classified as Group 3 ( ‘not classifiable as to its carcinogenicity to humans’) substances.
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
Justification for classification or non-classification
MMVF note Q fibres are fulfilling the note Q criterion in Regulation (EC) No 1227/2008 of December 2008 (see the end-point 7.12 for the biopersistence results of MMVF note Q fibres). Highly reliable studies documented that MMVF note Q fibres have no carcinogenic potential, neither in the lungs nor in pleura. Minor reversible lung effects were observed (nonspecific inflammation and minimal cellularity), and minimal collagen deposition, similar to what could be expected for any biologically inert dust at the same exposure level. Consequently, MMVF note Q fibres shall not be classified as carcinogenic according to the criteria in Council Directive 67/548/EEC and Regulation (EC) 1272/2008.
Additional information
A number of long-term inhalation carcinogenicity studies with MMVF note Q fibres have been performed with exposure of rats (140 male Fischer 344 rats) to size-separated respirable fractions in nose-only inhalation chambers for 6 hr/day, 5 days/week for 24 months plus an observation period of up to 6 months. Three of these studies are presented in this dossier. The air concentrations of MMVF note Q fibres were up to 30 mg/m3. Control animals were exposed to filtered air, only. These studies showed that MMVF note Q fibres did not induce lung fibrosis, lung tumours or mesothelioma. In one study exposure to MMVF note Q fibres was associated with a nonspecific inflammatory response in the lungs that did not progress after 6-12 months of exposure. Another study induced minimal lung cellularity that reversed after exposure was terminated.
All three studies showed that MMVF note Q fibres did not induce lung fibrosis, lung tumours or mesothelioma. Minor reversible lung effects were found, like nonspecific inflammation, minimal cellularity and minimal collagen deposition. It is evaluated that MMVF note Q fibres do not possess a carcinogenic potential.
Carcinogenicity: via inhalation route (target organ): respiratory: lung
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