Reaction mass of sodium chloride and potassium chloride and trisodium hexafluoroaluminate

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

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:

supporting study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study in conformance with requirements of the standard repeated dose toxicity testing protocols, assessment taken from EU-RAR.

Justification for type of information:

The read-across can be performed because trisodium hexafluoroaluminate is component parts of ADS 2-5, and is the only component with possible negative effects on human health. In view of this fact, we will detail its effect, based on published studies.

Principles of method if other than guideline:

Study in conformance with requirements of the standard repeated dose toxicity testing protocols.

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

other: : Crl:CD(SD)BR

Sex:

male/female

Route of administration:

oral: feed

Duration of treatment / exposure:

90 days

Frequency of treatment:

continuously

Remarks:

Doses / Concentrations:
3.8, 399.2, and 4172.3 mg/kg bw/day in males; 4.5, 455.9, and 4758.1 mg/kg bw/day in females
Basis:

Remarks:

Doses / Concentrations:
50, 5000, and 50000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

40

Control animals:

yes

Details on results:

At 50000 ppm male and female rats exhibited reduced body weights and decreases in haemoglobin and haematocrit. At necropsy the stomach of male and female rats receiving ≥5000 ppm exhibited thickened walls, dark contents, raised focal areas, glandular thickened walls, non-glandular light focal areas, glandular dark focal areas and red glandular areas. Microscopical examination revealed submucosal lymphoid foci, hyperplasia, hyperkeratosis/acanthosis, erosion/ulcerations, mucosal atrophy and chronic submucosal inflammation. Fluoride accumulated in bones and teeth at all dose levels. The LOAEL for fluoride accumulation for male and female rats was 50 ppm, representing 3.8/4.5 mg/kg bw/day. The NOAEL for this effect could not be determined in this study. The LOAEL for lesions observed in the stomach was 5000 ppm (399.2 mg/kg bw/day in males and 455.9 mg/kg bw/day in females). The NOAEL for stomach effects in rats was 50 ppm, representing 3.8 mg/kg bw/day in males and 4.5 mg/kg bw/day in females.

Dose descriptor:

LOAEL

Effect level:

4.5 mg/kg bw/day (nominal)

Based on:

other: fluoride accumulation in bones and teeth

Sex:

female

Dose descriptor:

LOAEL

Effect level:

3.8 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

other: fluoride accumulation in bones and teeth

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEL

4 172.3 mg/kg bw/day

Study duration:

subchronic

Experimental exposure time per week (hours/week):

168

Species:

rat

System:

gastrointestinal tract

Organ:

stomach

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other:

Remarks:

GLP compliant, guideline study, unpublished report available, no restrictions, fully adequate for assessment

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): cryolite
- Supplier: Bayer AG, Leverkusen, Germany
- Analytical purity: 98.9%
- Lot/batch No.: Partie no. 2

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles river Limited (Manston Road Margate, UK)
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: 142-146 g
- Housing: 5 or 6 of the same sex in a cage
- Diet: ad libitum, standard quality-controlled laboratory rat food
- Water: ad libitum, tap water

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21±3
- Humidity (%): 55±15
- Photoperiod (hrs dark / hrs light): 12 hours

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: The particulate aerosols employed in the study contained 86 to 89% respirable particles with diameters < 7 µm. The MMAD ranged from 1.9-2.8 for the different exposure concentrations.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dust generator (to produce an aerosol from the powder supplied)
- Exposure chamber: ADG snout-inhalation chamber
- Method of holding animals in test chamber: rat restraining tubes
- System of generating particulates/aerosols: Wright Dust Feed (WDF) mechanism
- Method of particle size determination: Marple Model 296 Personal Cascade impactor sampler
- Air supply: each exposure system was operated with an air extract attached to the base of the inhalation chamber. A supply of clean, dried compressed air was used to operate the WDF. A supplementary air supply was used to balance the chamber air flows. Air supplies were provided by a compressor, the air was filtered to remove any residual particulate and was dried, air extract was provided by vacuum pumps.

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric determination

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Gravimetric determination. Sampling (2-3 times per exposure day): collection using Whatman GF/A glass fibre filters (air was drawn through each filter in its holder using a vacuum pump). Volumes of each sample removed were measured by an in-line Wet-type gas meter

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

5 days/week, 6 hours/day

Remarks:

Doses / Concentrations:
0.85, 4.4, 23.3 mg/m3
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
0.21, 1.04, 4.6 mg/m3
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
0.2, 1.0 and 5.0 mg/m3
Basis:
other: target concentration

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

Rats in the air control group, sodium fluoride dose group, and high dose cryolite group were maintained in their holding cages for a 13 week period following the last exposure.

An additional group of rats was exposed to a (study mean analysed) concentration of 5.7 mg/m3 sodium fluoride, as a comparative control.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once each week

BODY WEIGHT: Yes
- Time schedule for examinations: once a week

FOOD CONSUMPTION: Yes
- Food consumption determination: weekly

WATER CONSUMPTION: Yes
- Time schedule for examinations: daily

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: once

HAEMATOLOGY: Yes
- Time schedule for collection of blood: once in week 13
- Anaesthetic used for blood collection: Yes --> ether
- Animals fasted: No
- How many animals: all

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: once in week 13
- Animals fasted: No
- How many animals: all

URINALYSIS: Yes
- Time schedule for collection of urine: once in week 13 and once in week 26
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes

Sacrifice and pathology:

Macroscopic examination and organ weights: Yes
Microscopic pathology: Yes

Other examinations:

Urinary inorganic fluoride and aluminium analysis: following urinanalysis during week 13, the residual individual samples were pooled for 5 rats of the same sex in each group. During week 26 (week 13 of withdrawal) urine samples were collected from all withdrawal rats and pooled for 5 rats of the same sex in each group.

Statistics:

All statistical analyses were carried out separately for males and females.Food and water consumption was analysed using cage mean values.
For all other parameters the analyses were carried out using individual animal as the experimental unit. Bodyweight data were analysed using weight gains. The following sequence of statistical tests was used for bodyweight, organ weight and clinical pathology data.
If the data consist predominantly of one particular value (relative frequency of the mode exceeded 75%), the proportion of animals with values different from the mode was analysed by appropriate methods. Otherwise:
Bartlett's test was applied to test for heterogeneity of variance between treatments; where significant (at the 1% level) heterogeneity was found, a logarithmic transformation was tried to see if a more stable variance structure could be obtained.
If no significant heterogeneity was detected (or if a satisfactory transformation was found), a one-way analysis of variance was carried out. If significant heterogeneity of variance was present, and could not be removed by a transformation, the Kruskal-Wallis analysis of ranks was used.
Except for pre-exposure data, analyses of variance were followed by a Student’s t test and Williams' test for a dose-related response, although only Williams' test was reported. The Kruskal-Wallis analyses were followed by Shirley's test, the non-parametric equivalent of the t test and Williams' tests.
Where appropriate, analysis of covariance was used in place of analysis of variance in the above sequence. For organ weight dat4 the final bodyweight was used as covariate in an attempt to allow for differences in bodyweight which might influence the organ weights.
For microscopic findings Fisher’s exact test was employed to detect treatment-related differences.

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 specified

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not specified

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:

no effects observed

Details on results:

At termination, increased inorganic fluoride concentrations in urine, bones, and teeth were evident for rats in the high dose cryolite (4.6 mg/m3) and the sodium fluoride dose group. Aluminium concentrations in the urine were increased in both sexes in the high and mid dose cryolite group, and in females in the low dose cryolite group. However, a dose relationship was not evident for this effect. Fluoride concentrations in bones and in tooth samples were increased in rats of both sexes of high dose cryolite group. Analysed values for aluminium in bones and teeth were below the limit of detection for the method of analysis used. After 13 weeks of recovery the fluoride levels and the aluminium concentrations in the urine and the fluoride concentration in the teeth of all groups returned to the control range, whereas the fluoride concentration in bones remained unchanged compared to terminal concentrations (no evidence for recovery was seen). Since the increased aluminium and inorganic fluoride excretion via urine could not be correlated to toxic effects, these findings were not considered to be toxicologically adverse.

At termination, increased lung weights were present in rats of both sexes of the high dose cryolite group. A similar but less obvious effect was present following 13 weeks of recovery.

The necropsy protocol was in line with recommendations in OECD TG 413. However, bones and teeth, considered likely to be target organs, were excluded from light microscopic examination. Pulmonary inflammatory lesions were observed in a majority of animals receiving cryolite at the high dose, and to a lesser degree, in some animals from the mid dose group. In the majority of animals from the high dose cryolite group, treatment-related findings in the lungs have comprised varying degrees of macrophage aggregation which contained brown pigmented material around alveolar ducts and alveolitis with thickening of alveolar duct walls. In addition, perivascular inflammatory infiltration with increased collagen in the alveolar duct walls and extension of bronchiolar epithelium into alveolar ducts were observed. Macrophages containing brown pigmented material were also present in the tracheobronchial and mediastinal lymph nodes of the high dose cryolite rats. The observed lung changes in cryolite exposed rats were typical of a non-specific reaction over time to a particulate with irritant properties, and attempts at clearance of deposited material via the lung macrophage/lymph node routs. No treatment-related laryngeal changes were seen in cryolite exposed animals. The treatment-related changes had, with the exception of the increased lung weights and the presence of small foci of brown pigmented alveolar macrophages, resolved after the recovery period.

Following exposure to sodium fluoride at 5.7 mg/m3, 6 out of 19 animals exhibited aggregations of alveolar macrophages in the lung parenchyma and around the alveolar ducts, 16 out of 19 animals had laryngeal epithelial hyperplasia and 9 out of 19 animals had subepithelial inflammation of the larynx. No treatment-related changes were seen in the lymph nodes of sodium fluoride exposed animals.

Overall, the response of respiratory tract inhalation exposure to sodium fluoride differed from the response to exposure to cryolite at a similar concentration and particle size. In rats exposed to sodium fluoride, lesions were noted in the larynx, whereas in rats exposed to cryolite, lesions were in the lungs. The reasons for the differences in localisation of the respiratory tract lesions may be related to the relative solubility of cryolite and sodium fluoride. Sodium fluoride is more soluble than cryolite and may not remain in the lungs in particulate form for a period of time sufficient to cause the degree of response seen with cryolite.

No effects of treatment were evident in clinical signs, bodyweight gain, food or water consumption. Haematological, biochemical and urinalysis parameters did not indicate findings considered of toxicological significance.

For cryolite, the NOAEC for systemic effects in male and female rats was 4.6 mg/m3 and the NOAEC for local toxic effects on the respiratory tract in rats was 0.21 mg/m3.

Dose descriptor:

NOAEC

Effect level:

0.21 mg/m³ air (nominal)

Sex:

male/female

Basis for effect level:

other: pulmonary inflammatory lesions

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

0.21 mg/m³

Study duration:

subchronic

Experimental exposure time per week (hours/week):

30

Species:

rat

System:

respiratory system: lower respiratory tract

Organ:

lungs

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other:

Remarks:

GLP compliant, guideline study, unpublished report available, no restrictions, fully adequate for assessment

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): cryolite
- Supplier: Bayer AG, Leverkusen, Germany
- Analytical purity: 98.9%
- Lot/batch No.: Partie no. 2

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles river Limited (Manston Road Margate, UK)
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: 142-146 g
- Housing: 5 or 6 of the same sex in a cage
- Diet: ad libitum, standard quality-controlled laboratory rat food
- Water: ad libitum, tap water

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21±3
- Humidity (%): 55±15
- Photoperiod (hrs dark / hrs light): 12 hours

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: The particulate aerosols employed in the study contained 86 to 89% respirable particles with diameters < 7 µm. The MMAD ranged from 1.9-2.8 for the different exposure concentrations.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dust generator (to produce an aerosol from the powder supplied)
- Exposure chamber: ADG snout-inhalation chamber
- Method of holding animals in test chamber: rat restraining tubes
- System of generating particulates/aerosols: Wright Dust Feed (WDF) mechanism
- Method of particle size determination: Marple Model 296 Personal Cascade impactor sampler
- Air supply: each exposure system was operated with an air extract attached to the base of the inhalation chamber. A supply of clean, dried compressed air was used to operate the WDF. A supplementary air supply was used to balance the chamber air flows. Air supplies were provided by a compressor, the air was filtered to remove any residual particulate and was dried, air extract was provided by vacuum pumps.

TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric determination

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Gravimetric determination. Sampling (2-3 times per exposure day): collection using Whatman GF/A glass fibre filters (air was drawn through each filter in its holder using a vacuum pump). Volumes of each sample removed were measured by an in-line Wet-type gas meter

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

5 days/week, 6 hours/day

Remarks:

Doses / Concentrations:
0.85, 4.4, 23.3 mg/m3
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
0.21, 1.04, 4.6 mg/m3
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
0.2, 1.0 and 5.0 mg/m3
Basis:
other: target concentration

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

Rats in the air control group, sodium fluoride dose group, and high dose cryolite group were maintained in their holding cages for a 13 week period following the last exposure.

An additional group of rats was exposed to a (study mean analysed) concentration of 5.7 mg/m3 sodium fluoride, as a comparative control.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once each week

BODY WEIGHT: Yes
- Time schedule for examinations: once a week

FOOD CONSUMPTION: Yes
- Food consumption determination: weekly

WATER CONSUMPTION: Yes
- Time schedule for examinations: daily

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: once

HAEMATOLOGY: Yes
- Time schedule for collection of blood: once in week 13
- Anaesthetic used for blood collection: Yes --> ether
- Animals fasted: No
- How many animals: all

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: once in week 13
- Animals fasted: No
- How many animals: all

URINALYSIS: Yes
- Time schedule for collection of urine: once in week 13 and once in week 26
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes

Sacrifice and pathology:

Macroscopic examination and organ weights: Yes
Microscopic pathology: Yes

Other examinations:

Urinary inorganic fluoride and aluminium analysis: following urinanalysis during week 13, the residual individual samples were pooled for 5 rats of the same sex in each group. During week 26 (week 13 of withdrawal) urine samples were collected from all withdrawal rats and pooled for 5 rats of the same sex in each group.

Statistics:

All statistical analyses were carried out separately for males and females.Food and water consumption was analysed using cage mean values.
For all other parameters the analyses were carried out using individual animal as the experimental unit. Bodyweight data were analysed using weight gains. The following sequence of statistical tests was used for bodyweight, organ weight and clinical pathology data.
If the data consist predominantly of one particular value (relative frequency of the mode exceeded 75%), the proportion of animals with values different from the mode was analysed by appropriate methods. Otherwise:
Bartlett's test was applied to test for heterogeneity of variance between treatments; where significant (at the 1% level) heterogeneity was found, a logarithmic transformation was tried to see if a more stable variance structure could be obtained.
If no significant heterogeneity was detected (or if a satisfactory transformation was found), a one-way analysis of variance was carried out. If significant heterogeneity of variance was present, and could not be removed by a transformation, the Kruskal-Wallis analysis of ranks was used.
Except for pre-exposure data, analyses of variance were followed by a Student’s t test and Williams' test for a dose-related response, although only Williams' test was reported. The Kruskal-Wallis analyses were followed by Shirley's test, the non-parametric equivalent of the t test and Williams' tests.
Where appropriate, analysis of covariance was used in place of analysis of variance in the above sequence. For organ weight dat4 the final bodyweight was used as covariate in an attempt to allow for differences in bodyweight which might influence the organ weights.
For microscopic findings Fisher’s exact test was employed to detect treatment-related differences.

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 specified

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not specified

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:

no effects observed

Details on results:

At termination, increased inorganic fluoride concentrations in urine, bones, and teeth were evident for rats in the high dose cryolite (4.6 mg/m3) and the sodium fluoride dose group. Aluminium concentrations in the urine were increased in both sexes in the high and mid dose cryolite group, and in females in the low dose cryolite group. However, a dose relationship was not evident for this effect. Fluoride concentrations in bones and in tooth samples were increased in rats of both sexes of high dose cryolite group. Analysed values for aluminium in bones and teeth were below the limit of detection for the method of analysis used. After 13 weeks of recovery the fluoride levels and the aluminium concentrations in the urine and the fluoride concentration in the teeth of all groups returned to the control range, whereas the fluoride concentration in bones remained unchanged compared to terminal concentrations (no evidence for recovery was seen). Since the increased aluminium and inorganic fluoride excretion via urine could not be correlated to toxic effects, these findings were not considered to be toxicologically adverse.

At termination, increased lung weights were present in rats of both sexes of the high dose cryolite group. A similar but less obvious effect was present following 13 weeks of recovery.

The necropsy protocol was in line with recommendations in OECD TG 413. However, bones and teeth, considered likely to be target organs, were excluded from light microscopic examination. Pulmonary inflammatory lesions were observed in a majority of animals receiving cryolite at the high dose, and to a lesser degree, in some animals from the mid dose group. In the majority of animals from the high dose cryolite group, treatment-related findings in the lungs have comprised varying degrees of macrophage aggregation which contained brown pigmented material around alveolar ducts and alveolitis with thickening of alveolar duct walls. In addition, perivascular inflammatory infiltration with increased collagen in the alveolar duct walls and extension of bronchiolar epithelium into alveolar ducts were observed. Macrophages containing brown pigmented material were also present in the tracheobronchial and mediastinal lymph nodes of the high dose cryolite rats. The observed lung changes in cryolite exposed rats were typical of a non-specific reaction over time to a particulate with irritant properties, and attempts at clearance of deposited material via the lung macrophage/lymph node routs. No treatment-related laryngeal changes were seen in cryolite exposed animals. The treatment-related changes had, with the exception of the increased lung weights and the presence of small foci of brown pigmented alveolar macrophages, resolved after the recovery period.

Following exposure to sodium fluoride at 5.7 mg/m3, 6 out of 19 animals exhibited aggregations of alveolar macrophages in the lung parenchyma and around the alveolar ducts, 16 out of 19 animals had laryngeal epithelial hyperplasia and 9 out of 19 animals had subepithelial inflammation of the larynx. No treatment-related changes were seen in the lymph nodes of sodium fluoride exposed animals.

Overall, the response of respiratory tract inhalation exposure to sodium fluoride differed from the response to exposure to cryolite at a similar concentration and particle size. In rats exposed to sodium fluoride, lesions were noted in the larynx, whereas in rats exposed to cryolite, lesions were in the lungs. The reasons for the differences in localisation of the respiratory tract lesions may be related to the relative solubility of cryolite and sodium fluoride. Sodium fluoride is more soluble than cryolite and may not remain in the lungs in particulate form for a period of time sufficient to cause the degree of response seen with cryolite.

No effects of treatment were evident in clinical signs, bodyweight gain, food or water consumption. Haematological, biochemical and urinalysis parameters did not indicate findings considered of toxicological significance.

For cryolite, the NOAEC for systemic effects in male and female rats was 4.6 mg/m3 and the NOAEC for local toxic effects on the respiratory tract in rats was 0.21 mg/m3.

Dose descriptor:

NOAEC

Effect level:

0.21 mg/m³ air (nominal)

Sex:

male/female

Basis for effect level:

other: pulmonary inflammatory lesions

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: dermal, other

Type of information:

experimental study

Adequacy of study:

other information

Study period:

1996

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: The study is unacceptable because the test substance was likely ingested during the study.

Dose descriptor:

NOAEL

Effect level:

1 020 mg/kg bw/day

Sex:

male/female

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 020 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: dermal, other

Type of information:

experimental study

Adequacy of study:

other information

Study period:

1996

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: The study is unacceptable because the test substance was likely ingested during the study.

Dose descriptor:

NOAEL

Effect level:

1 020 mg/kg bw/day

Sex:

male/female

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Mode of Action Analysis / Human Relevance Framework

In an epidemiological study, no definite indications of skeletal effects were seen in aluminium smelter workers with long-term occupational exposure to 0.48 mg fluoride/m3.

Additional information

There are two 2-week range finding inhalation toxicity studies (in conformance with requirements of the standard repeated dose toxicity testing protocols) in rats available. The data were used to establish exposure concentrations for use in a 90-day investigation. Cryolite was administered to Sprague-Dawley CD rats for 6 hours a day, 5 days a week for 2 weeks by inhalation of particulates of the test substance using a whole body exposure system. In the first study, groups of rats (5/sex/group) were exposed to cryolite concentrations of 60 mg/m³ (low dose), 130 mg/m³ (mid dose), or 470 mg/m³ (high dose). In the second study with identical group arrangement the mean exposure levels were 5.1 mg/m³(low dose) or 13.6 mg/m³(high dose). A further group of rats (5/sex) acting as a control was exposed to air only.

In both range finding studies, no treatment-related mortalities were reported. In addition, no other relevant treatment related systemic effects were found in both studies.

A NOAEC for local effects (effects on the lungs) could not be established for both studies. So, the lowest concentration tested in both 2-week range finding inhalation toxicity studies, 5.1 mg/m³, was set as LOAEC (Huntingdon Research Centre Ltd., 1994a, 1994b).

In the 90-day inhalation study according to OECD TG 413 (the recovery period was extended to 13 weeks) groups of Sprague-Dawley CD rats (10/sex/group) were snout-only exposed to cryolite concentrations of 0, 0.21, 1.04, and 4.6 mg/m³ for 6 hours a day, 6 days a week for a period of 13 consecutive weeks (Huntingdon Life Sciences Ltd., 1997a).

At termination, increased lung weights were present in rats of both sexes of the high dose cryolite group. A similar but less obvious effect was present following 13 weeks of recovery. Pulmonary inflammatory lesions were observed in a majority of animals receiving cryolite at the high dose, and to a lesser degree, in some animals from the mid dose group. In the majority of animals from the high dose cryolite group, treatment-related findings in the lungs have comprised varying degrees of macrophage aggregation which contained brown pigmented material around alveolar ducts and alveolitis with thickening of alveolar duct walls. In addition, perivascular inflammatory infiltration with increased collagen in the alveolar duct walls and extension of bronchiolar epithelium into alveolar ducts were observed. Macrophages containing brown pigmented material were also present in the tracheobronchial and mediastinal lymph nodes of the high dose cryolite rats. The observed lung changes in cryolite exposed rats were typical of a non-specific reaction over time to a particulate with irritant properties, and attempts at clearance of deposited material via the lung macrophage/lymph node routs. No treatment-related laryngeal changes were seen in cryolite exposed animals. The treatment-related changes had, with the exception of the increased lung weights and the presence of small foci of brown pigmented alveolar macrophages, resolved after the recovery period.

No effects of treatment were evident in clinical signs, bodyweight gain, food or water consumption. Haematological, biochemical and urinalysis parameters did not indicate findings considered of toxicological significance.

In conclusion, the NOAEC for systemic effects in male and female rats was 4.6 mg/m³ and the NOAEC for local toxic effects on the respiratory tract in rats was 0.21 mg/m³.

In the key epidemiological study, no definite cases of skeletal fluorosis occurred among the 570 pot room workers at an aluminium smelter who were exposed to about 0.48 mg fluoride/m³ for at least 50% of their time at work for more than 10 years. There were no observed differences among the groups with regard to occurrence of back and joint problems (Chan-Yeung et al., 1983). Based on this study, a systemic NOAEC of 0.48 mg/m³ is established.

Data on oral animal toxicity studies in conformance with requirements of the standard repeated dose toxicity testing protocols are reported. Fluoride accumulation was the critical adverse effect in several feeding studies in rats and dogs. Fluoride was accumulated at all dose levels of cryolite tested in rats and dogs for different duration of exposure. It was not possible to identify the NOAEL for this effect in any of the repeated oral dose studies. After a repeated administration of cryolite for 90 days fluoride accumulation was observed in rats from the lowest dose tested of 50 ppm (3.8 mg/kg bw/day in males, 4.5 mg/kg bw/day in females) upwards (Weltman, 1996), and in dogs from 500 ppm (17 mg/kg bw/day) upwards (Hagen and Strouse, 1996), respectively.

In repeated dose toxicity studies data on clinical and histopathological examinations of teeth were not routinely reported. Indicators of dental fluorosis as enamel striations, changes in colouration and physical properties of the teeth (hypoplasia/hypomineralisation of dental enamel and dentine) have been noted in albino rats receiving cryolite at 0.58 mg/kg bw/day for 14 weeks (University of Illinois).

For local effects of cryolite on the digestive tract a local NOAEL of 50 ppm (corresponding to about 3.8 mg/kg bw/day in males, and 4.5 mg/kg bw/d in females) could be derived from the 90-day feeding study in rats (Weltman, 1996). Lesions in the stomach, including epidermal hyperplasia and hyperkeratosis/acanthosis in the nonglandular portion of the stomach, and submucosal inflammation in the glandular portion, were observed in Crl:CD(SD)BR rats at ≥5000 ppm (corresponding to about ≥399.2 mg/kg bw/day in males and ≥455.9 mg/kg bw/day in females) after a 90 day administration in the diet. The gastrointestinal lesions were probably caused by hydrofluoric acid (hydrogen fluoride), which can be released from ingested cryolite in the stomach.

For the dermal route, no reliable data are available.

Justification for classification or non-classification

Local effect in rats after subchronic inhalation of predominantly respirable cryolite dust was lung toxicity seen as interstitial pneumonia at a low concentration of 1.04 mg/m³(0.001 mg/L) cryolite (90-day inhalation study, 6 hours/day, 5 days/week (Huntington Life Sciences Ltd., 1997a)). This concentration is far below the cut-off value of 0.25 mg/L established by EU Directive 67/548/EEC for attributing R48/20 (Harmful: danger of serious damage to health by prolonged exposure by inhalation) in a 90-day inhalation study. According to EU Directive 67/548/EEC, classification with R48/23 (Toxic: danger of serious damage to health by prolonged exposure by inhalation) should be applied if the effects are observed at levels of one order of magnitude lower (i.e. 10-fold) than the cut-off value for classification with R48/20. Therefore, classification with R48/23 is appropriate in accordance to Directive 67/548/EEC. Under EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, classification with H372 (STOT, Cat. 1) is applicable for the inhalation route.

 

The critical effect following repeated dietary exposure to cryolite in experimental animals was fluoride accumulation and its effect on non-neoplastic bone disease - skeletal fluorosis - observed in rats (males/females) from the lowest dose tested of 3.8/4.5 mg/kg bw/day upward and in dogs from 17 mg/kg bw/day, respectively (90-day studies). Dental fluorosis (hypoplasia/hypomineralisation of dental enamel and dentine) represents a most sensitive adverse effect related to cryolite treatment. Changes in dental enamel described as striations in tooth enamel were observed after giving cryolite in diet and drinking water to rats at 0.58 mg/kg bw/day for 14 weeks. Toxic effects on the bones and teeth in rats were also reported in early repeated dose toxicity studies. These identified dose levels are far below the cut-off value for attributing R48/22 (50 mg/kg bw/day) in a 90-day study in rats according to EU Directive 67/548/EEC. Similarly, as the dose level at which these effects are observed are over 10 times lower than the cut-off level for classification with R48/22, classification and labelling with T, R48/25 (Toxic: danger of serious damage to health by prolonged exposure if swallowed) should be applied. Under EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, classification with H372 (STOT, Cat. 1) is applicable for the oral route.