Calcium fluoride

Endpoint summary

Description of key information

Acute oral toxicity:

The key acute oral toxicity study on calcium difluoride yielded an LD50 > 2000 mg CaF₂/kg bw/d in rats.

Acute dermal toxicity

No acute dermal toxicity study on calcium difluoride is available. Dermal acute toxicit information is however available for read-across source substance sodium fluoride (NaF). The dermal LD50 of NaF is found to be > 2000 mg NaF/kg bw/d in rats. As a consequence, it can be reasonably expected that the dermal acute toxicity of calcium difluoride is low too.

Acute inhalation toxicity

The key acute inhalation toxicity study on calcium difluoride yielded an inhalation LC50 of 5070 mg CaF₂/m³.

Conclusion:

The substance is of low acute toxicity.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 February to 16 March, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline-compliant study

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Qualifier:

according to guideline

Guideline:

other: Japan MAFF Testing Guideline of 12 Nosan No. 8147

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

The animals were nulliparous and non-pregnant female Wistar rats of the Crl:WI (Han) strain. They were obtained from Charles River Wiga GmbH (Germany) and were approximately 10 weeks old at the start of the study. They were allowed an acclimatisation period of at least 5 days before the beginning of the experimental phase. Individuals were identified by cage cards and tail markings.
The rats were housed in fully air-conditioned rooms, maintained at a temperature of 22±3°C and 30-70% relative humidity. Light was provided on a 12 hour light/dark cycle. The rats were singly housed in Makrolon type III cages, with bedding and enrichment provided. They were fed VRF1(P) diet (SDS, Germany), and tap water was available ad libitum.

Feed, drinking water, bedding and enrichment analyses were conducted.

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

doubly distilled

Details on oral exposure:

Each rat received a single oral administration by gavage.
The dosing preparation (suspension) was produced for each test group shortly before administration by stirring with a magnetic stirrer. The homogeneity of the preparation during application was ensured by stirring with a magnetic stirrer.
Doubly distilled water was chosen as the vehicle as an aqueous formulation corresponds to the physiological medium. The administration volume was 10 ml/kg bw.

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

Two groups of 3 females.

Control animals:

no

Details on study design:

A starting dose of 2000 mg/kg be was chosen in the first step with 3 females. No animals died, so 2000 mg/kg bw was administered to another group of 3 females. As no animal died in the second step the study was termination.
Feed was withdrawn from the animals at least 16 hours before administration, but water was available ad libitum. Dosing took place in the morning. The rats were observed for 14 days after dosing.
Individual body weights were obtained shortly before administration (day 0), weekly thereafter and on the last day of observation. Clinical signs were erecorded several times on the day of administration, and at least once daily thereafter each workday. A check for dead or moribund animals was made at least once each workday. Rats were sacrificed at the end of the observation period by exposure to increasing concentrations of CO2. Necropsy with gross pathology was performed.

Statistics:

A formal statistical analysis was nto required.

Preliminary study:

No preliminary study available.

Key result

Sex:

female

Dose descriptor:

LD0

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: No deaths at the limit dose

Mortality:

No mortality occurred.

Clinical signs:

other: No clinical signs were observed in the first adminstration group. Clinical observations in the second group revealed reduced impaired general state, piloerection, diarrhoea and dyspnoea in one out of three animals from hour 2 until hour 5 after administra

Gross pathology:

There were no macroscopic pathological findings.

Other findings:

No other findings reported.

No further information on results.

Interpretation of results:

GHS criteria not met

Conclusions:

The acute oral LD50 in rats was estimated to be >2000 mg/kg bw.

Executive summary:

The acute oral toxicity of calcium fluoride was evaluated according to the Acute Toxic Class method. Calcium fluoride was administered as a suspension in doubly distilled water, by gavage, to two groups of 3 female Wistar rats at a dose of 2000 mg/kg bw.

No mortality ccurred in the six females. No clinical signs were observed in the first adminstration group. Clinical observations in the second group revealed reduced impaired general state, piloerection, diarrhoea and dyspnoea in one out of three animals from hour 2 until hour 5 after administration. The mean body weight of the test groups increased throughout the study period within the normal range. There were no macroscopic pathological findings.

The acute oral LD50 in rats was estimated to be >2000 mg/kg bw.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Reliable limit dose study completed in accordance with current test guidelines.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14-28 November 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Proprietary GLP guideline compliant study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals were male and female SPF-reared Wistar derived (Crl:[WI]WU BR) rats obtained from Charles River Wiga GmbH, Germany. Rats were aged 5- 6 weeks on arrival, they were checked for overt signs of ill health and anomalies, then kept in quarantine. Rats were separated by sex and uniquely indenitifed by ear tattoo. The mean body weights of the rats at the start of the study were 308 g for the males and 208 g for the females. The duration of acclimatisation in the animal room was 42 days.

The rats were housed under conventional conditions in suspended stainless steel cages. There were approximately 10 air changes per hour. The temperature was 20.2 - 24.3°C, and relative humidity was 40 - 88%. Transgressions of the 70% relative humidity limit were limited to not more than 0.5% of the total time that the animals spent in the room. A 12 hour light/dark cycle was maintained. Food and water were provided ad libitum, except during exposure. Rats were fed a commercial rodent diet (Rat & Mouse No. 3 Breeding Diet RM3) from SDS, England. Tap water was supplied in bottles which were filled up as required.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

Animals were exposed to the test atmosphere in a nose-only inhalation camber. The column had a volume of approximately 50 L and consisted of a top assembly with two mixing chambers, underneath a rodent tube section and the exhaust section at the bottom. The rats were secured in plastic animal holders, positioned radially through the outer cylinder around the central column. Only the nose of the rat protruded into the interior of the column. A positive pressure was maintained in the central column and a slightly negative pressure in the outer cylinder to prevent dilution/escape of the test atmosphere.

The test material was ground with a blender to produce particles of an acceptable size. The test atmosphere was generated by passing test material to an eductor using a dry material feeder. The eductor was operated with pressurised humidifed air. The test material was delivered in a slip stream of ambient air, and the rats were exposed to a continuous supply of fresh test atmosphere. The animals were placed in the exposure unit after stabilisation of the est atmosphere. The air flow delivered was 83.1 l/min.

During exposure, 57% of the aerosol present at the rats breathing zone was contained in particles with an aerodynamic diameter equal to or smaller than 3.0 µm. The value of the MMAD measured during exposure was 2.8 µm. The distribution of particle sizes had a geometric standard deviation of 1.9. The mean temperature during exposure was 22.0±0.3°C, and the mean relative humidity was 44±1%. The oxygen concentration during exposure was 20.9%.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

The concentration of the aerosol in the test atmosphere was determined once per hour by gravimetric analysis

Duration of exposure:

4 h

Concentrations:

The nominal concentration was calculated to be 10.5 g/m3. The actual concentration based on gravimetric analysis was 5.07±0.04 g/m3.

No. of animals per sex per dose:

5 rats per sex.

Control animals:

no

Details on study design:

The rats were exposed to the test atmosphere for 4 hours. They were then observed for a 14 day period; behaviour, clinical signs and mortality were recorded just prior to and during exposure, shortly after and at least once daily thereafter. Body weights were recorded just prior to exposure and on days 7 and 14. Necropsy and macroscopic examination was carried out at the end of the 14 day observation period.

Statistics:

Not applicable.

Preliminary study:

Not applicable.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5 070 mg/m³ air (analytical)

Exp. duration:

4 h

Remarks on result:

other: No mortality occurred. MMAD 2.8 um.

Mortality:

No mortalities occurred during exposure or during the 14 day observation period.

Clinical signs:

other: A slightly decreased breathing rate was observed in one male and one female at the final observation time during exposure. No other abnormalities were noted either during or exposure or during the observation period.

Body weight:

Overall body weight gain in males was considered to be within normal limits for animals of this strain and age. Overall body weight gain in females was considered to be low (Table 1).

Gross pathology:

Red/pink discolouration of the lungs was observed in two females. One petechia was found in a male, which is occasionally observed in non-treated control animals.

Other findings:

No other findings were reported.

Mean body weights (g) of male and female rats

	Day 0	Day 7	Day 14
Males
mean	307.9	315.7	328.6
sd	15.4	16.0	16.8
Females
mean	207.6	209.1	212.8
sd	15.3	15.5	14.2

Interpretation of results:

GHS criteria not met

Conclusions:

The 4-hour acute inhalation LC50 of calcium fluoride was greater than 5.07 g/m3 for both sexes.

Executive summary:

The acute inhalation toxicity of calcium fluoride was studied by nose-only exposure of one group of five male and five female rats for a 4 hour period. The test atmosphere contained calcium fluoride dust (MMAD 2.8 um) at the limit concentration of 5.07 g/m³. After exposure the animals were kept for a 14-day observation period, then necropsied. Treatment-related effects seen during exposure were limited to a slightly decreased breathing rate in two animals. No further abnormalities were detected during after exposure or during the 14 day observation period. A low overall body weight gain was seen in females. At necropsy, treatment related macroscopic changes were limited to red/pink discolouration of the lungs in two females. The 4-hour LC₅₀ value of an aerosol of calcium fluoride was found to be greater than 5.07 g/m³ for both sexes under the conditions of this study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

5 070 mg/m³ air

Quality of whole database:

Reliable limit dose study completed in accordance with current test guidelines.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Acute oral toxicity:

Three studies are available in which the acute oral toxicity of calcium difluoride is assessed. The key study (Cords & Lammer, 2010) was performed in 2010 in accordance with GLP and the applicable OECD guideline. The study concludes that the oral LD50 of calcium difluoride in rats is > 2000 mg CaF₂/kg bw/d.

Two older studies (Tarasenko, 1977 and Simonin, 1937) yield and oral LD50 of 4250 mg CaF₂/kg bw in rats, and an oral LD50 > 5000 mg CaF₂/kg bw in guinea pigs.

The dossier furthermore includes a number of studies on the read-across source substances sodium fluoride (NaF). Sodium fluoride is found to have an oral LD50 of 223 mg NaF/kg bw in rats, which would correspond to an oral LD50 of 207 mg CaF₂/kg bw for calcium fluoride.

Please refer to the read-across justificaiton for a comparisson of the tox properties of the read-across source and target substances.

Acute dermal toxicity

No studies are available that examine the acute dermal toxicity of calcium difluoride.

Acute inhalation toxicity

One study is available in which the acute inhalation toxicity of calcium difluoride is assessed. The study (Mommers, 2002) was performed in accordance with GLP and the applicable OECD guideline. The study concludes that the inhalation LC50 of CaF₂is 5070 mg CaF₂/m³.

Please refer to the read-across justificaiton for a comparisson of the tox properties of the read-across source and target substances.

Acute toxicity, other routes: intraperitoneal:

One study is available in which the acute toxicity of calcium difluoride is assessed upon intraperitoneal injection. The corresponding LD50 was found to be 2778 mg CaF₂/kg bw.

Conclusion:

The substance is of low acute toxicity by the oral, inhalation and intraperitoneal routes and low acute dermal toxicity can be reliably predicted.

Justification for classification or non-classification

The substance is of low acute toxicity by the oral, inhalation and intraperitoneal routes and low acute dermal toxicity can be reliably predicted. No classification is proposed for acute toxicity according to the CLP regulation (1272/2008/EC).