Decamethylcyclopentasiloxane

Endpoint summary

Description of key information

A well reported 90-day oral study (Bayer AG, 1991), conducted in the main according to the current guideline and in accordance with GLP is reported. For the purposes of human hazard assessment, the NOAEL is considered to be greater than or equal to the highest dose tested, 1000 mg/kg/day.

 

The key repeated dose inhalation toxicity study (RCC Ltd., 2005) is a two-year combined chronic toxicity and carcinogenicity study in rats conducted to an EPA guideline, to OECD guideline 453 and to GLP. In these studies the highest vapour concentration that could be reliably and effectively generated without appreciable aerosol or condensation was observed to be 160 ppm. The NOAEC for general toxicity in this study was ≥160 ppm (2420 mg/m3; the highest dose tested). Local effects on the nasal cavity and adaptive increases in liver weights (with no microscopic findings) were observed. The NOAEC for carcinogenic effects was ≥160ppm (2420mg/m3).

 

In the key dermal study, administration of undiluted D5 under occlusive conditions over a 28-day period at doses up to and including 1600 mg/kg bw/day resulted in no adverse effects on survival, body weight, food consumption, clinical observations, clinical pathology, haematology, ophthalmoscopy, organ weights, or gross or microscopic pathology, and no dermal irritation (Dow Corning Corporation 1990d).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07.11.1988 to 10.02.1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

version from May 12, 1981

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Stamm Bor:WISW (SPF-Cpb), Versuchstierzucht Winkelmann, Borchen, Germany
- Age at study initiation: 7 weeks
- Weight at study initiation: Males: 129-165 g; Females: 102-141 g
- Fasting period before study:
- Housing: Makrolon Type II cages, 5 animals per cage
- Diet (e.g. ad libitum): Ad libitum, nutrition composition and contaminants are given
- Water (e.g. ad libitum): Ad libitum,
- Acclimation period: 8 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 2
- Humidity (%): ca. 50
- Air changes (per hr): ca. 10
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 07.11.1988 To: 10.02.1989

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

Vehicle dispensed daily by gavage, reference animals were given water by the same route.
Dose volume: Since 100% concentration of substance was administered, dose volume changed with dose:
0.1 ml/kg
0.33 ml/kg
1 ml/kg

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

no details given on verification of dose; the volume of substance was measured

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

daily

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Dose / conc.:

330 mg/kg bw/day (actual dose received)

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

Ten

Control animals:

other: control animals were given dose of water by the same route.

Details on study design:

- Dose selection rationale: Dose was selected based on published and non-published results from chemically similar substance studies. 1000 mg/kg was fixes as upper limit following OECD recommendation. A factor of 3 was used for lower doses.
- Rationale for animal assignment (if not random): Randomization was carried out with computerized method
- Rationale for selecting satellite groups: No satellite groups
- Post-exposure recovery period in satellite groups: No

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily during the week, once daily on Saturdays and Sundays

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: daily monitoring

FOOD CONSUMPTION:
- Food consumption was determined daily for each individual animal. Mean daily diet consumption was calculated as g food/kg body weight/day: Data are given

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

WATER CONSUMPTION: Yes
- Time schedule for examinations: water uptake was determined for weekly periods for each individual animal

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: 3 days before first dosage and at the end of the test before the blood test
- Dose groups that were examined: all rats of the control group and all rats of the maximum dose group

HAEMATOLOGY: Yes
- Time schedule for collection of blood: week 5 and week 14 of test for all animals
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: (all)
- Parameters checked see table No. 1 below. Also differential blood count data are reported.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: week 5 and week 14 of test for all animals
- Animals fasted: No data
- How many animals: (all)
- Parameters checked in table 1 below.

URINALYSIS: Yes
- Time schedule for collection of urine: week 5 and week 13 of test for all animals
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters checked in table [No.113191/90] Urine volume was measured using calibrated test tubes, and urine colour and turbidity were visually assessed. Urinalysis parameters were urine pH, protein, glucose, ketone, bilirubin, blood and urobilinogen

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, A complete necropsy was conducted on all animals.

HISTOPATHOLOGY: Yes, was carried out at Institute for Toxicology Pharma, Bayer AG, Registration Number 2953.
see table 2.

Statistics:

Data are given as arithmetic mean with standard deviation; Organ weights are given as 95 and 99 Percentile values. Control group data were compared using significance tests (U-Test). Differences exceeding the significance levels 5% and 1% are labelled in the result tables.
It is noted that the total error probability increases with number of comparisons carried out. To compensate overestimation of significance values the biological and toxicological relevance was considered in the evaluation. All statistical tests were performed using appropriate computing devices or programs.

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):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

no tumour found

Details on results:

CLINICAL SIGNS AND MORTALITY: During the study two male (dose group 1000 mg/kg, due to dosing error or not considered treatment-related) and three female animals of various groups died. The substance treatment was excluded as reason for the fatalities.

BODY WEIGHT, WEIGHT GAIN AND FOOD CONSUMPTION: Female rats in both low dose groups show partly significant higher body weights than the control groups. This was not considered toxiclologically relevant. Slightly higher water consumption in all dose groups compare to control groups was observed. No clear treatment-related effects were reported on the other end points.

HAEMATOLOGY: The high dose groups (both m/f) showed significantly lower hemoglobin concentration after 13 weeks.

CLINICAL CHEMISTRY: a reduction of bilirubin values of all dose groups and calcium was higher in female dose groups and chloride was lower in all female dose groups. Chloride findings were not considered toxicologically relevant.

ORGAN WEIGHTS: Female rats in all dose groups showed significantly increased liver weights of up to 62% compare to the control group (see below).

GROSS PATHOLOGY: One female in the 100 mg/kg group had a glassy solid lump in the lung parenchyma. In the 330 mg/kg group 8 males and 6 females exhibited glassy and/or hard lumps in the lung parenchyma (2 - 15mm diameter). In the 1000mg/kg group six males and 6 females had lumps of 3 - 10 mm diameter in the lung parenchyma.
For one male in the highest dose group testes were observed to be smaller; one female of the high dose group exhibited an increased glassy right lymph node (3 mm).

HISTOPATHOLOGY: The glassy lumps which were observed in pathology were confirmed in the lung examinations.
Results on lungs, lymph nodes and liver are given in the detailed summary below.
Other organs were examined but indicated no treatment related damage.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on toxicological effects relevant to humans.

Critical effects observed:

no

Summary report on Histopathology (Dr. Eike Hartmann, pathologist, Bayer, July 1, 2005)

Ten male and female Wistar rats received undiluted Cyclomethicone D5 at doses of 0 (tap water) — 100 — 330 — 1000 mg/kg once daily for 13 weeks by gavage. In this study H&E stained paraffin sections of the lungs, trachea, liver, kidneys, heart, spleen, stomach, intestine, mesenteric lymph node, and gross lesions were examined from rats of all dose groups. On lungs and mesenteric lymph nodes also special staining methods like the Periodic —Acid —Schiff reaction, an Elastica van Gieson, and/or an Oil red 0 stains were applied.

Lungs:

At necropsy, lung nodules (hard, glassy/gray) of varying size were reported predominantly located in the apical or cranial parts of the diaphragmatic lobes close to the bronchi. The combined incidence for either sex was 0 / 1 / 14 / 12 out of 20 rats per group. Microscopically, granulomatous pneumonia characterized by an accumulation of vacuolated macrophages, solid granulomas, giant cells, necrosis, hemorrhage, granulocytic infiltration, suppurative foci, and /or type II pneumocyte proliferation was observed in males in the incidence 0 / 0 / 9 / 8 and in females in the incidence 0 / 1 / 7/ 6. An accompanying goblet cell hypertrophy of larger bronchi occurred in males at 330 mg/kg and in females at 100 mg/kg and above. Among affected mid and high dose rats similar severity scores were given for both lung findings ranging from grade 1 to grade 5. The lesions were restricted to lung lobes involved macroscopically, other parts of the lungs demonstrated no relevant histopathologic alterations.

Localization, morphologic pattern and resorptive character of the pneumonic changes are presumed to be the result of the test compound reaching the lungs by the airways unintentionally (e.g. by the methods of administration) and subsequent aspiration. They are not considered as systemic alterations caused by the test material and reaching the lungs by the bloodstream.

Mesenteric Lymph nodes:

Histiocytosis was found in almost all males and females at 100 mg/kg and above. The sinus of affected lymph nodes contained foci of macrophages loaded with foamy material. These changes were not associated with leukocytic infiltration or necrosis. Frequency and severity score were not dose dependent in males. In females, the most

severe lesions were observed at 1000 mg/kg. Similar grades were given in females of the low and mid dose group. Histiocytosis of the mesenteric lymph node can be explained by absorption of test compound or metabolites by the intestinal mucosa and its transfer to the local lymph node where it is phagocytosed by sinusoidal macrophages / histiocytes. These processes did not provoke any inflammatory reactions.

Liver:

Several animals receiving 1000 mg/kg had hepatocytic cytoplasmic changes which were interpreted as morphologic sign of an adaption to increased metabolic activity. These liver cell changes are not considered as adverse effects.

Conclusions:

A well reported 90-day oral study, conducted in the main according to the current guideline and in accordance with GLP is reported. In the study damage to the lungs and lymph nodes was seen at all dose levels. However, he effects on the lungs were considered by the pathologist to be due to aspiration of the test substance, and the effects on the lymph nodes are physical rather than due to systemic toxicity. For the purposes of human hazard assessment, the NOAEL is therefore considered to be greater than or equal to the highest dose tested, 1000 mg/kg bw/day.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: inhalation

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01.12.1999 to 09.06.2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Qualifier:

according to guideline

Guideline:

other: EPA OPPTS 870.4300

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories Inc.
- Age at study initiation: Six weeks
- Weight at study initiation: Males: 92-130 g; Females: 80-112 g.
- Fasting period before study: No, but animals not fed during exposure
- Housing: Groups of up to five animals of same sex in Makrolon type IV cages
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: Ten days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 3
- Humidity (%): 40-70
- Air changes (per hr):10-15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 14.12.1999 To: 09.06.2005

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: filtered air

Remarks on MMAD:

MMAD / GSD: The saturated vapour concentration of D5 was experimentally evaluated to be 180 ppm, and therefore is expected to be in vapour phase without liquid or mist particles at the concentration of 160 ppm.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Sealed chambers used for group isolation. Constructed from stainless steel, with glass doors. The chamber contained nine stainless steel wire cage units with excreta pan below each cage unit.
- Method of holding animals in test chamber: wire cage
- Source and rate of air: Compressed air (40 l/min) was supplied into the glass flasks and allowed the liquid to equilibrate with the temperature of the warm walls of the container. The vapour produced then passed through a pipe and was then mixed and diluted with 380 l/min of the filtered air to the chamber inlet duct. It passed through an ULTRA filter JK-S-19/30 filter before entering the exposure chamber. The temperature of the D5 vapour in the round flask was approx. 30oC in Group 2 (10 ppm), 50oC in Group 3 (40 ppm) and 80oC in Group 4 (160 ppm).


TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration in each chamber of the dose groups was determined daily, approximately five times per hour of exposure. Concentrations were determined by GC analysis.

Duration of treatment / exposure:

Sub-group A: interim sacrifice after 6 months; 26 weeks.
Sub-group B: interim sacrifice after 1 year; 52 weeks.
Sub-group C: sacrifice after 2 years, 1 year of exposure and 1 year of recovery.
Sub-group D: oncogenicity phase; up to 106 weeks.

Frequency of treatment:

Daily, 6 hours/day, 5 days/week

Dose / conc.:

0.15 mg/L air (nominal)

Remarks:

10 ppm (nominal)

Dose / conc.:

0.6 mg/L air (nominal)

Remarks:

40 ppm (nominal)

Dose / conc.:

2.42 mg/L air (nominal)

Remarks:

160 ppm (nominal)

No. of animals per sex per dose:

Subgroup A: 6; subgroup B: 10; subgroup C: 20; subgroup D: 60.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The highest exposure concentration is the highest vapour concentration that can be repetitively and reliably generated in whole-body exposure chambers for a study of this duration.
- Rationale for animal assignment (if not random): Random
- Rationale for selecting satellite groups: to investigate reversibility of adverse effects
- Post-exposure recovery period in satellite groups: one year

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily, as soon as possible following each exposure.
- Cage side observations for clinical signs of toxicity: behaviour, body position, respiration, nasal and ocular changes.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice during acclimitisation, weekly during weeks 2 to 14, then once every two weeks thereafter until the end of the study.


BODY WEIGHT: Yes
- Time schedule for examinations: During acclimitisation on day 1, 6 and on the day before the first exposure. The once weekly for the first 14 weeks. Thereafter the animals were weighed every four weeks until termination. In sub-groups C and D animals were weighed at the start of the week of terminal sacrifice. Animals were always weighed prior to daily exposure.


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No

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


WATER CONSUMPTION: No


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations:
- Dose groups that were examined: All animals in sub-group B, C and D before the start of exposure, and all surviving animals in control and highest dose groups of sub-group B, the last 10 animals/sex of sub-group C, and the first 10 animals/sex of sub-group D in control and highest dose groups prior to necropsy.


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 3, 6, and 12 months of exposure
- Anaesthetic used for blood collection: Yes (ether)
- Animals fasted: Yes
- How many animals: First ten animals/sex/group from sub-group C
- Parameters checked in table 1 were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: 3, 6, and 12 months of exposure
- Animals fasted: Yes
- How many animals: First ten animals/sex/group from sub-group C
- Parameters checked in table 1 were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: 3, 6, and 12 months of exposure
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked in table were examined.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 2)
HISTOPATHOLOGY: Yes (see table 2)

All animals that survived until sacrifice as well as all moribund animals were sacrificed. All macroscopic abnormalities were described and reported. All gross masses and clinically observed growths were confirmed at necropsy.

Subgroup A (6 month sacrifice): A portion of the liver was collected from all animals. A partial necropsy was performed on all animals in this group. Blood from cardiac puncture, peri-renal fat, abdominal fat and brown fat were also collected for determination of D5 concentration.
Subgroup B (sacrificed after one year): A portion of the liver was collected from all animals. Organ to body weight and organ to brain weight ratios were calculated. A complete necropsy was performed on all animals that died, were euthanised moribund or sacrificed at scheduled necropsy.
Subgroup C and D (sacrificed after 24 months): Organ to body weight and organ to brain weight ratios were calculated. A complete necropsy was performed on all animals that died, were euthanised moribund or sacrificed at scheduled necropsy.

Microscopic examinations were performed on control and highest dose group from sub-groups B, C and D. The lungs, liver, kidneys, nasal cavities and gross lesions and tissue masses were examined from all animals in groups 1, 2, 3 and 4 of sub-groups B, C and D.

Other examinations:

None

Statistics:

Analysis was two-tailed for significance levels of 5% and 1%. Generally, means are presented with standard deviations. Analysis of body weight, as well as organ weights and clinical pathology were analysed by a one way analysis of variance followed by comparison of control group to each treated group y Dunnett's test. The Steel test was applied instead of Dunnett's test if the data could not be assumed to follow a normal distribution. Fisher's Exact test was used to test for statistical significances between groups for the macroscopic and ophthalmoscopic data. Statistical analysis of histopathology data were recorded.

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 examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY: No treatment-related effect on mortality. Approximately one third of animals died in sub-groups C and D. There were no clinical signs that were considered to be related to the exposure to D5.

BODY WEIGHT AND WEIGHT GAIN: No statistically significant treatment-related differences between D5 treated groups and controls.

OPHTHALMOSCOPIC EXAMINATION: No treatment-related adverse effects.

There were no major effects of toxicological significance on haematology, clinical biochemistry and urinalysis data. However, for some parameters minor intergroup differences were recorded between treated rats and controls at different time points of the treatment.

HAEMATOLOGY: The only possible effect on haematology parameters was confined to reduction in the red blood cell count with associated changes in the mean cell volume and mean cell haemoglobin values in males at 40 and 160 ppm. However, the change was temporary and minimal in degree and therefore considered to be of no toxicological importance.

CLINICAL CHEMISTRY: The decrease in urea concentration and increase in cholesterol/triglycerides, proteins and gamma glutamyl transferase in the females were possibly related to treatment with D5 and suggest metabolic adaptive changes, primarily related to the liver. The only other change considered to be related to treatment was an increased calcium level in males and females at 160 ppm. No toxicological relevance is associated with these findings since the changes were minimal in degree and unaccompanied by any pathological findings.

URINALYSIS: Urinalysis changes (especially those in males after three months) were small, not present at subsequent measurements, had no pathological correlates and therefore were considered to be of no toxicological importance.

ORGAN WEIGHTS: The only organ weight changes that were considered to be possibly related to treatment with D5 were the increased liver weights in females after 6 and 12 months and in males after 2 years. However, this finding was not present in males after 6 and 12 months or females after 2 years, showed no relationship to dose (not apparent in females at 40 ppm) and there were no correlated findings at histopathological examination. Therefore this finding could be the consequence of a transient metabolic adaptation without any toxicological relevance.

GROSS PATHOLOGY: There were no treatment-related masses found in any group. See also Section 7.7.

HISTOPATHOLOGY: NON-NEOPLASTIC: The statistically significantly increased incidence of hyaline inclusions in the nasal respiratory/olfactory epithelium was noted in male and/or female rats of group 4 (160 ppm) sacrificed after 6, 12 and 24 months and are considered to represent a non-specific exposure-related effect. An increased incidence of hyaline inclusions was noted also in high dose males after the recovery period. It was not clear from this study whether or not this increase was related to the exposure. Histomorphologic changes in the nasal cavity were consistent with chronic inhalation of some mildly irritant chemicals but are also commonly observed in ageing rats. Since there were no other changes associated with a response to an irritant, such as an inflammatory cell infiltration or degenerative changes to the epithelium, the finding was considered to be non-specific and of low toxicological importance.

HISTOPATHOLOGY: NEOPLASTIC: See Section 7.7.

OTHER: TISSUE CONCENTRATIONS: Determination of the D5 levels in plasma, fat and liver following six months of exposures showed an increase with the dose, with slightly higher values in the fat and liver recorded for females compared with males.

Dose descriptor:

NOAEC

Remarks:

General toxicity

Effect level:

>= 160 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

other: No toxicologically relevant adverse effects at any concentration tested. Excluding local effects in nasal cavity.

Dose descriptor:

NOAEC

Remarks:

Carcinogenicity

Effect level:

>= 160 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

other: Based on uterine tumours following 24 months exposure to 160 ppm being not relevant to humans.

Dose descriptor:

NOAEC

Remarks:

local effects

Effect level:

40 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on respiratory tract irritation

Critical effects observed:

no

Conclusions:

In a two-year inhalation combined chronic toxicity and carcinogenicity study in rats conducted to an EPA guideline and to GLP (reliability score 1) the NOAEC for general toxicity was ≥160 ppm (2.42 mg/l; the highest dose tested). Local effects on the nasal cavity and adaptive increases in liver weights (with no microscopic findings) in females were observed at 160 ppm. The NOAEC for carcinogenic effects was 40 ppm (0.6 mg/l) based on uterine tumours at 160 ppm.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

2 420 mg/m³

Study duration:

chronic

Species:

rat

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: inhalation

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01.12.1999 to 09.06.2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Qualifier:

according to guideline

Guideline:

other: EPA OPPTS 870.4300

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories Inc.
- Age at study initiation: Six weeks
- Weight at study initiation: Males: 92-130 g; Females: 80-112 g.
- Fasting period before study: No, but animals not fed during exposure
- Housing: Groups of up to five animals of same sex in Makrolon type IV cages
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: Ten days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 3
- Humidity (%): 40-70
- Air changes (per hr):10-15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 14.12.1999 To: 09.06.2005

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: filtered air

Remarks on MMAD:

MMAD / GSD: The saturated vapour concentration of D5 was experimentally evaluated to be 180 ppm, and therefore is expected to be in vapour phase without liquid or mist particles at the concentration of 160 ppm.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Sealed chambers used for group isolation. Constructed from stainless steel, with glass doors. The chamber contained nine stainless steel wire cage units with excreta pan below each cage unit.
- Method of holding animals in test chamber: wire cage
- Source and rate of air: Compressed air (40 l/min) was supplied into the glass flasks and allowed the liquid to equilibrate with the temperature of the warm walls of the container. The vapour produced then passed through a pipe and was then mixed and diluted with 380 l/min of the filtered air to the chamber inlet duct. It passed through an ULTRA filter JK-S-19/30 filter before entering the exposure chamber. The temperature of the D5 vapour in the round flask was approx. 30oC in Group 2 (10 ppm), 50oC in Group 3 (40 ppm) and 80oC in Group 4 (160 ppm).


TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration in each chamber of the dose groups was determined daily, approximately five times per hour of exposure. Concentrations were determined by GC analysis.

Duration of treatment / exposure:

Sub-group A: interim sacrifice after 6 months; 26 weeks.
Sub-group B: interim sacrifice after 1 year; 52 weeks.
Sub-group C: sacrifice after 2 years, 1 year of exposure and 1 year of recovery.
Sub-group D: oncogenicity phase; up to 106 weeks.

Frequency of treatment:

Daily, 6 hours/day, 5 days/week

Dose / conc.:

0.15 mg/L air (nominal)

Remarks:

10 ppm (nominal)

Dose / conc.:

0.6 mg/L air (nominal)

Remarks:

40 ppm (nominal)

Dose / conc.:

2.42 mg/L air (nominal)

Remarks:

160 ppm (nominal)

No. of animals per sex per dose:

Subgroup A: 6; subgroup B: 10; subgroup C: 20; subgroup D: 60.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The highest exposure concentration is the highest vapour concentration that can be repetitively and reliably generated in whole-body exposure chambers for a study of this duration.
- Rationale for animal assignment (if not random): Random
- Rationale for selecting satellite groups: to investigate reversibility of adverse effects
- Post-exposure recovery period in satellite groups: one year

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily, as soon as possible following each exposure.
- Cage side observations for clinical signs of toxicity: behaviour, body position, respiration, nasal and ocular changes.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice during acclimitisation, weekly during weeks 2 to 14, then once every two weeks thereafter until the end of the study.


BODY WEIGHT: Yes
- Time schedule for examinations: During acclimitisation on day 1, 6 and on the day before the first exposure. The once weekly for the first 14 weeks. Thereafter the animals were weighed every four weeks until termination. In sub-groups C and D animals were weighed at the start of the week of terminal sacrifice. Animals were always weighed prior to daily exposure.


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No

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


WATER CONSUMPTION: No


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations:
- Dose groups that were examined: All animals in sub-group B, C and D before the start of exposure, and all surviving animals in control and highest dose groups of sub-group B, the last 10 animals/sex of sub-group C, and the first 10 animals/sex of sub-group D in control and highest dose groups prior to necropsy.


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 3, 6, and 12 months of exposure
- Anaesthetic used for blood collection: Yes (ether)
- Animals fasted: Yes
- How many animals: First ten animals/sex/group from sub-group C
- Parameters checked in table 1 were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: 3, 6, and 12 months of exposure
- Animals fasted: Yes
- How many animals: First ten animals/sex/group from sub-group C
- Parameters checked in table 1 were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: 3, 6, and 12 months of exposure
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked in table were examined.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 2)
HISTOPATHOLOGY: Yes (see table 2)

All animals that survived until sacrifice as well as all moribund animals were sacrificed. All macroscopic abnormalities were described and reported. All gross masses and clinically observed growths were confirmed at necropsy.

Subgroup A (6 month sacrifice): A portion of the liver was collected from all animals. A partial necropsy was performed on all animals in this group. Blood from cardiac puncture, peri-renal fat, abdominal fat and brown fat were also collected for determination of D5 concentration.
Subgroup B (sacrificed after one year): A portion of the liver was collected from all animals. Organ to body weight and organ to brain weight ratios were calculated. A complete necropsy was performed on all animals that died, were euthanised moribund or sacrificed at scheduled necropsy.
Subgroup C and D (sacrificed after 24 months): Organ to body weight and organ to brain weight ratios were calculated. A complete necropsy was performed on all animals that died, were euthanised moribund or sacrificed at scheduled necropsy.

Microscopic examinations were performed on control and highest dose group from sub-groups B, C and D. The lungs, liver, kidneys, nasal cavities and gross lesions and tissue masses were examined from all animals in groups 1, 2, 3 and 4 of sub-groups B, C and D.

Other examinations:

None

Statistics:

Analysis was two-tailed for significance levels of 5% and 1%. Generally, means are presented with standard deviations. Analysis of body weight, as well as organ weights and clinical pathology were analysed by a one way analysis of variance followed by comparison of control group to each treated group y Dunnett's test. The Steel test was applied instead of Dunnett's test if the data could not be assumed to follow a normal distribution. Fisher's Exact test was used to test for statistical significances between groups for the macroscopic and ophthalmoscopic data. Statistical analysis of histopathology data were recorded.

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 examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY: No treatment-related effect on mortality. Approximately one third of animals died in sub-groups C and D. There were no clinical signs that were considered to be related to the exposure to D5.

BODY WEIGHT AND WEIGHT GAIN: No statistically significant treatment-related differences between D5 treated groups and controls.

OPHTHALMOSCOPIC EXAMINATION: No treatment-related adverse effects.

There were no major effects of toxicological significance on haematology, clinical biochemistry and urinalysis data. However, for some parameters minor intergroup differences were recorded between treated rats and controls at different time points of the treatment.

HAEMATOLOGY: The only possible effect on haematology parameters was confined to reduction in the red blood cell count with associated changes in the mean cell volume and mean cell haemoglobin values in males at 40 and 160 ppm. However, the change was temporary and minimal in degree and therefore considered to be of no toxicological importance.

CLINICAL CHEMISTRY: The decrease in urea concentration and increase in cholesterol/triglycerides, proteins and gamma glutamyl transferase in the females were possibly related to treatment with D5 and suggest metabolic adaptive changes, primarily related to the liver. The only other change considered to be related to treatment was an increased calcium level in males and females at 160 ppm. No toxicological relevance is associated with these findings since the changes were minimal in degree and unaccompanied by any pathological findings.

URINALYSIS: Urinalysis changes (especially those in males after three months) were small, not present at subsequent measurements, had no pathological correlates and therefore were considered to be of no toxicological importance.

ORGAN WEIGHTS: The only organ weight changes that were considered to be possibly related to treatment with D5 were the increased liver weights in females after 6 and 12 months and in males after 2 years. However, this finding was not present in males after 6 and 12 months or females after 2 years, showed no relationship to dose (not apparent in females at 40 ppm) and there were no correlated findings at histopathological examination. Therefore this finding could be the consequence of a transient metabolic adaptation without any toxicological relevance.

GROSS PATHOLOGY: There were no treatment-related masses found in any group. See also Section 7.7.

HISTOPATHOLOGY: NON-NEOPLASTIC: The statistically significantly increased incidence of hyaline inclusions in the nasal respiratory/olfactory epithelium was noted in male and/or female rats of group 4 (160 ppm) sacrificed after 6, 12 and 24 months and are considered to represent a non-specific exposure-related effect. An increased incidence of hyaline inclusions was noted also in high dose males after the recovery period. It was not clear from this study whether or not this increase was related to the exposure. Histomorphologic changes in the nasal cavity were consistent with chronic inhalation of some mildly irritant chemicals but are also commonly observed in ageing rats. Since there were no other changes associated with a response to an irritant, such as an inflammatory cell infiltration or degenerative changes to the epithelium, the finding was considered to be non-specific and of low toxicological importance.

HISTOPATHOLOGY: NEOPLASTIC: See Section 7.7.

OTHER: TISSUE CONCENTRATIONS: Determination of the D5 levels in plasma, fat and liver following six months of exposures showed an increase with the dose, with slightly higher values in the fat and liver recorded for females compared with males.

Dose descriptor:

NOAEC

Remarks:

General toxicity

Effect level:

>= 160 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

other: No toxicologically relevant adverse effects at any concentration tested. Excluding local effects in nasal cavity.

Dose descriptor:

NOAEC

Remarks:

Carcinogenicity

Effect level:

>= 160 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

other: Based on uterine tumours following 24 months exposure to 160 ppm being not relevant to humans.

Dose descriptor:

NOAEC

Remarks:

local effects

Effect level:

40 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on respiratory tract irritation

Critical effects observed:

no

Conclusions:

In a two-year inhalation combined chronic toxicity and carcinogenicity study in rats conducted to an EPA guideline and to GLP (reliability score 1) the NOAEC for general toxicity was ≥160 ppm (2.42 mg/l; the highest dose tested). Local effects on the nasal cavity and adaptive increases in liver weights (with no microscopic findings) in females were observed at 160 ppm. The NOAEC for carcinogenic effects was 40 ppm (0.6 mg/l) based on uterine tumours at 160 ppm.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

600 mg/m³

Study duration:

chronic

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11.07.1988 to 12.03.1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Deviations:

yes

Remarks:

Limited haematology

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles Rivers Breeding Laboratories, Portage, Michigan
- Age at study initiation: 'young'
- Weight at study initiation: males: 259-286 g; females: 215-263 g
- Fasting period before study: No data
- Housing: Individually in standard stainless steel wire mesh cages of conventional design
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: Seven days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ±3
- Humidity (%): 30-70
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To:

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: Dorsal area
- % coverage: approx. 10%
- Type of wrap if used: Occluded with plastic wrap
- Time intervals for shavings or clippings: as needed


REMOVAL OF TEST SUBSTANCE
- Washing (if done): No

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): No data
- Constant volume or concentration used: No data


USE OF RESTRAINERS FOR PREVENTING INGESTION: no

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

28 days

Frequency of treatment:

Once daily for 6 hr/day, 7d/week, for 28 days

Dose / conc.:

200 mg/kg bw/day (actual dose received)

Dose / conc.:

800 mg/kg bw/day (actual dose received)

Dose / conc.:

1 600 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10 per sex in main study groups, 5 per sex in the 2 satellite groups.

Control animals:

other: occluded with plastic wrap, but without test material

Details on study design:

- Dose selection rationale: No data
- Rationale for animal assignment (if not random): random
- Rationale for selecting satellite groups: reversibility of adverse effects (control and 1600 mg/kg bw/day groups)
- Post-exposure recovery period in satellite groups: 28 days

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily for all groups

DETAILED CLINICAL OBSERVATIONS: No

DERMAL IRRITATION (if dermal study): No

BODY WEIGHT: Yes
- Time schedule for examinations: study initiation, weekly throughout the study and at termination, including the post-exposure rest period.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes


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

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: study initiation and termination
- Dose groups that were examined: control and high dose group animal

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At study termination
- Anaesthetic used for blood collection: Yes (ketamine HCl)
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table 1 were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At study termination
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table 1 were examined


URINALYSIS: Yes
- Time schedule for collection of urine: At study termination
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked in table 1 were examined.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 2)
HISTOPATHOLOGY: Yes (see table 2)

Other examinations:

None

Statistics:

Body weight, food consumption, hematology, clinical chemistry, urinalysis, organ weights analysed by 1-way ANOVA.
Group means compared with controls using Dunnett's multiple T-test or non-parametric analysis of variance by ranks
where appropriate.

Clinical signs:

no effects observed

Dermal irritation:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Details on results:

• Body weight: No significant differences were found.
• Food/water consumption: No significant differences were found.
• Description, severity, time of onset and duration of clinical signs: No significant clinical observations or
behavioural changes were reported.
• Ophthalmologic findings incidence and severity: No adverse effects observed.
• Hematological findings incidence and severity: No significant changes were reported.
• Clinical biochemistry findings incidence and severity: No significant changes were reported for clinical chemistry or
urinalysis results.
• Mortality and time to death: No unscheduled early deaths occurred during this study.
• Gross pathology incidence and severity: There were no apparent treatment-related effects noted at gross necropsy.
• Organ weight changes: No significant changes were reported
• Histopathology incidence and severity: No significant dose-related findings were reported for either terminal or
recovery group sacrifices.

Dose descriptor:

NOAEL

Effect level:

>= 1 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No systemic effects observed.

Dose descriptor:

NOAEL

Effect level:

>= 1 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No local effects observed.

Critical effects observed:

no

Conclusions:

Dermal administration of undiluted D5 under occlusive conditions over a 28-day period at doses up to and including 1600 mg/kg bw/day resulted in no adverse effects on survival, body weight, food consumption, clinical observations, clinical pathology, hematology, ophthalmoscopy, organ weights, or gross or microscopic pathology (study reliability score 1).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 600 mg/kg bw/day

Study duration:

subacute

Species:

rat

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11.07.1988 to 12.03.1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Deviations:

yes

Remarks:

Limited haematology

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles Rivers Breeding Laboratories, Portage, Michigan
- Age at study initiation: 'young'
- Weight at study initiation: males: 259-286 g; females: 215-263 g
- Fasting period before study: No data
- Housing: Individually in standard stainless steel wire mesh cages of conventional design
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: Seven days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ±3
- Humidity (%): 30-70
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To:

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: Dorsal area
- % coverage: approx. 10%
- Type of wrap if used: Occluded with plastic wrap
- Time intervals for shavings or clippings: as needed


REMOVAL OF TEST SUBSTANCE
- Washing (if done): No

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): No data
- Constant volume or concentration used: No data


USE OF RESTRAINERS FOR PREVENTING INGESTION: no

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

28 days

Frequency of treatment:

Once daily for 6 hr/day, 7d/week, for 28 days

Dose / conc.:

200 mg/kg bw/day (actual dose received)

Dose / conc.:

800 mg/kg bw/day (actual dose received)

Dose / conc.:

1 600 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10 per sex in main study groups, 5 per sex in the 2 satellite groups.

Control animals:

other: occluded with plastic wrap, but without test material

Details on study design:

- Dose selection rationale: No data
- Rationale for animal assignment (if not random): random
- Rationale for selecting satellite groups: reversibility of adverse effects (control and 1600 mg/kg bw/day groups)
- Post-exposure recovery period in satellite groups: 28 days

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily for all groups

DETAILED CLINICAL OBSERVATIONS: No

DERMAL IRRITATION (if dermal study): No

BODY WEIGHT: Yes
- Time schedule for examinations: study initiation, weekly throughout the study and at termination, including the post-exposure rest period.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes


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

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: study initiation and termination
- Dose groups that were examined: control and high dose group animal

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At study termination
- Anaesthetic used for blood collection: Yes (ketamine HCl)
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table 1 were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At study termination
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table 1 were examined


URINALYSIS: Yes
- Time schedule for collection of urine: At study termination
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked in table 1 were examined.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 2)
HISTOPATHOLOGY: Yes (see table 2)

Other examinations:

None

Statistics:

Body weight, food consumption, hematology, clinical chemistry, urinalysis, organ weights analysed by 1-way ANOVA.
Group means compared with controls using Dunnett's multiple T-test or non-parametric analysis of variance by ranks
where appropriate.

Clinical signs:

no effects observed

Dermal irritation:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Details on results:

• Body weight: No significant differences were found.
• Food/water consumption: No significant differences were found.
• Description, severity, time of onset and duration of clinical signs: No significant clinical observations or
behavioural changes were reported.
• Ophthalmologic findings incidence and severity: No adverse effects observed.
• Hematological findings incidence and severity: No significant changes were reported.
• Clinical biochemistry findings incidence and severity: No significant changes were reported for clinical chemistry or
urinalysis results.
• Mortality and time to death: No unscheduled early deaths occurred during this study.
• Gross pathology incidence and severity: There were no apparent treatment-related effects noted at gross necropsy.
• Organ weight changes: No significant changes were reported
• Histopathology incidence and severity: No significant dose-related findings were reported for either terminal or
recovery group sacrifices.

Dose descriptor:

NOAEL

Effect level:

>= 1 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No systemic effects observed.

Dose descriptor:

NOAEL

Effect level:

>= 1 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No local effects observed.

Critical effects observed:

no

Conclusions:

Dermal administration of undiluted D5 under occlusive conditions over a 28-day period at doses up to and including 1600 mg/kg bw/day resulted in no adverse effects on survival, body weight, food consumption, clinical observations, clinical pathology, hematology, ophthalmoscopy, organ weights, or gross or microscopic pathology (study reliability score 1).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Study duration:

subacute

Species:

rat

Additional information

The key oral repeated dose toxicity study (Bayer AG, 1991) was conducted according to OECD test guideline 408 (except for neurobehavioural tests),. Wistar rats (10 animals/sex/dose) were administered D5 by oral gavage at doses of 100, 330 or 1000mg/kg bw/day for 13 weeks. The animals were observed and examined according to the guideline. The animals had normal food consumption and normal body weight gain. There was no indication of adverse effects on blood or haematopoietic organs, kidney and liver. There was a substance-related increase in histiocytes in mesenteric lymph nodes for 100mg/kg bw/day and above. Also observed were macroscopic and microscopic changes in lung parenchyma. However, the effects on the lungs were considered by the pathologist to be due to aspiration of the test substance following dosing errors, and the effects on the lymph nodes are physical rather than due to systemic toxicity. Therefore, the NOAEL for systemic effects relevant to humans was ≥1000mg/kg bw/day.

The key inhalation repeated dose toxicity study (RCC Ltd, 2005) was conducted to EPA OPPTS 870.4300 (combined chronic toxicity/carcinogenicity), which is equivalent to OECD test guideline 453. Fischer 344 rats were exposed, whole body, to D5 vapour at concentrations of 10, 40 or 160ppm (150, 600 and 2420 mg/m³). Exposures were 6 hours/day, 5 days/week. The animals were divided into 4 subgroups. Sub-group A (6 animals) was sacrificed after 6 months of treatment; subgroup B (10 animals) was sacrificed after 1 year; subgroup C (20 animals) was treated with D5 for 1 year and then allowed to recover for 1 year after which they were sacrificed; subgroup D (60 animals) was sacrificed after 2 years of treatment. The only systemic effect was increased liver weight without related histopathological findings; however, these were considered to be adaptive changes and are therefore not of toxicological relevance. The statistically significantly increased incidence of hyaline inclusions in the nasal respiratory/olfactory epithelium was noted in male and/or female rats of group 4 (160 ppm) sacrificed after 6, 12 and 24 months and are considered to represent a non-specific exposure-related effect. An increased incidence of hyaline inclusions was noted also in high dose males after the recovery period. It was not clear from this study whether or not this increase was related to the exposure. Histomorphologic changes in the nasal cavity were consistent with chronic inhalation of some mildly irritant chemicals but are also commonly observed in ageing rats. Since there were no other changes associated with a response to an irritant, such as an inflammatory cell infiltration or degenerative changes to the epithelium, the finding was considered to be non-specific and of low toxicological importance. The NOAEC for systemic effects was ≥160ppm (2420mg/m³) and the NOAEC for local effects based on respiratory tract irritation was 40ppm (600mg/m³). The NOAEC for carcinogenic effects was ≥160ppm (2420mg/m³) (discussed further in Section 7.7).

Administration of D5 by oral or inhalation routes causes a reversible hepatomegaly accompanied by an increase in metabolic enzymes in male and female rats. It has been determined that the observed increase in liver weight and enzyme induction are not indicative of liver toxicity. Rather, the observed effects are an adaptive change indicative of metabolic adaptation. The effects are reversible, even with continued exposure to D5, and are comparable to the liver changes observed in rats following phenobarbital administration. Therefore, these effects with D5 are classified as “Phenobarbital-like” (SEHSC, CES and SIAJ, 2005). There are several studies that support the conclusion that the liver effects that following administration of D5 are adaptive rather than toxic. Since these studies are mechanistic rather than standard animal studies, they are included in Section 7.9.3 (Specific Investigations).

The key dermal repeated dose toxicity study (Dow Corning Corporation, 1990) was conducted according to OECD test guideline 410. Sprague-Dawley rats (control and high dose groups: 10 animals/sex/group; low and mid dose groups: 5 animals/sex/group) were dermally exposed to undiluted D5 at doses of 200, 800, 1600 mg/kg bw/day, using an occlusive dressing. Exposure was 6 hours/day, 7 days/week for 28 days. This study included a 28 day recovery period in which half the control and highest dose group animals were observed and examined following a 28 -day treatment period and 28 -day recovery period. Apart from slightly restricted haematology examinations the animals were observed and examined according to the test guideline. There were no adverse findings for survival, body weight, food consumption, clinical observations, clinical pathology, haematology, ophthalmoscopy, organ weights, or gross or microscopic pathology, and no dermal irritation. Therefore, the NOAEL for systemic and local effects was ≥1600mg/kg bw/day.

It is also of note that the kinetics of D5 in rats following oral administration are different to other routes of exposure and therefore make interpretation of hazard identification data difficult. The kinetics of D5 following inhalation and dermal exposure are similar and therefore comparable and allow for the development of physiologically based pharmacokinetic models that enable accurate predictions of human exposure by these routes. Following oral administration, D5 appears to enter the blood via the lymphatics within the lipid core of chylomicrons and other lipoproteins, which is in a form different from that for inhalation or dermal routes of exposure. Given the route-specific nature of D5 pharmacokinetics, data collected using the oral route of exposure does not give a meaningful understanding of the tissue kinetics of D5 by relevant routes of human exposure (SEHSC, CES and SIAJ, 2005).

SEHSC, CES and SIAJ (2005). Decamethylcyclopentasiloxane (D5): A White Paper on Health Research Findings. June 2005.

Justification for classification or non-classification

Based on the available data D5 does not require classification for repeated dose toxicity according to Regulation (EC) No. 1272/2008.