Calcium fluoride

Acute Toxicity: inhalation

Administrative data

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

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

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

Test material

Test material information

Constituent 1

Reference substance name:

Calcium fluoride

EC Number:

232-188-7

EC Name:

Calcium fluoride

Cas Number:

7789-75-5

Molecular formula:

CaF2

IUPAC Name:

calcium difluoride

Test material form:

other: solid

Details on test material:

Calcium fluoride (CaF2), a crystalline white powder, stored at ambient temperature.

Test animals

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.

Administration / exposure

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.

Results and discussion

Preliminary study:

Not applicable.

Effect levels

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.

Any other information on results incl. tables

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

Applicant's summary and conclusion

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.