Silicic acid, calcium salt

Endpoint summary

Description of key information

Acute toxicity via inhalation: LC50 >4.907 mg/L

Key value for chemical safety assessment

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:

December 15, 2010 - December 30, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Test was performed according to OECD Guideline 403 and under GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

no

Principles of method if other than guideline:

Not applicable

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:

TEST ANIMALS
- Source: Toxi-Coop Zrt. 1103 Budapest, Cserkesz u. 90.
- Age at study initiation: Young adult rats, 8-12 weeks old
- Weight at study initiation: Male: 308-321 g; Female: 208-219 g
- Housing: Group caging (2 or 3 animals, by sex, per cage)
- Diet: ssniff® SM R/M-Z+H complete diet ad libitum
- Water: tap water from watering bottles ad libitum
- Acclimation period: 20 days
- Acclimatisation to the test apparatus: 11 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): 8-12
- Photoperiod (hrs dark / hrs light): Artificial light, from 6 a.m. to 6 p.m.

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: nose-only dynamic flow type cylindrical two-level exposure chamber
- Exposure chamber volume: 1.1L
- Method of holding animals in test chamber: The animals were held in polycarbonate restraining tubes and exposed “nose-only” under dynamic air flow conditions.
- Source and rate of air: The air was supplied by an oil-free air compressor and was filtered in a two-stage filter set. Air flow rate: 19.9 L/min; air flow rate to each animal port: 1.24 L/min.
- System of generating particulates/aerosols: dust aerosol generator type Wright
- Method of particle size determination: 7-stage cascade impactor type 02-150
- Temperature, humidity in air chamber: 21.4-23.2 °C, 0-8.3 %.

TEST ATMOSPHERE
- Brief description of analytical method used: Aerosol Light Scattering Photometer
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: Inhalable Fraction (% < 4μm): 58
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.55 μm / 2.90

Analytical verification of test atmosphere concentrations:

yes

Remarks:

combination of the gravimetric results and the recorded real-time data provided by the Aerosol Light Scattering Photometer integrated in the monitoring system of the exposure apparatus

Duration of exposure:

ca. 4 h

Concentrations:

4.907 mg/L (Mean Achieved Concentration)
(Nominal concentration 15.9 mg/L air)

No. of animals per sex per dose:

5 animals/sex/dose

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days.
- Frequency of observations and weighing: Animals were checked twice daily during the observation period for morbidity and/or mortality. All animals were observed for clinical signs at 1st, 2nd and 3rd hours during exposure, as soon as practicable following removal from restraint, 1 hour after exposure and subsequently once daily for 14 days. Individual bodyweights were recorded on the day of exposure Day 0 (prior to exposure) and Days 1, 3, 7 and 15.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, other: gross necropsies included a detailed examination of the abdominal and thoracic cavities with special attention given to the respiratory tract for macroscopic signs of irritancy or local toxicity.

Statistics:

No statistical analysis was performed.

Preliminary study:

Not applicable

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4.907 mg/L air (analytical)

Exp. duration:

4 h

Remarks on result:

other: No mortality occured

Sex:

male/female

Dose descriptor:

LC0

Effect level:

> 4.907 mg/L air (analytical)

Exp. duration:

4 h

Remarks on result:

other: No mortality occured

Mortality:

No mortality observed during the study.

Clinical signs:

other: No test item related effects were found in the male and female animals during the inhalation exposure and observation period.

Body weight:

In both genders body weight loss was observable on the day of inhalation exposure. In both sexes a compensation of body weight loss was found from the third day of the observation period. On the basis of body weight and body weight gain data, there was no notable test item effect observable in the exposed animals.

Gross pathology:

In the female dose group 1 case of hydrometra occurred. The hydrometra is an alteration with sporadic occurrence in experimental rats without toxicological meaning. No test item-related macroscopic findings were observed.

Other findings:

None

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the experimental conditions of this study, no deaths occurred in a group of 10 rats exposed to a mean atmospheric concentration of 4.907 mg/L for 4 hours. The acute inhalation median lethal concentration (4h LC50) of test item Crystalline calcium silicate hydrates (xonotlite – tobermorite), in Wistar Crl:(WI) BR rats, was therefore considered to be higher than 4.907 mg/L. As no deaths occurred the tested concentration can be considered as LC0. Based on these results Crystalline calcium silicate hydrates (xonotlite – tobermorite) does not have to be classified and has no obligatory labeling requirement for acute inhalation toxicity according to the criteria outlined in Annex I of 1272/2008/EC and Annex VI of 67/548/EEC.

Executive summary:

An assessment of acute inhalatory toxicity with Crystalline calcium silicate hydrates (xonotlite – tobermorite) in the rat was performed according to OECD Guideline No.403, September 2009. The test material was administered as an aerosol by inhalation for 4 hours to one group of 5 male and 5 female Wistar Crl:(WI) BR rats. Animals were checked twice daily during the observation period for morbidity and/or mortality. All animals were observed for clinical signs during exposure after 1, 2 and 3 hours, as soon as practicable following removal from restraint, 1 hour after exposure and subsequently once daily for 14 days. Individual bodyweights were recorded on the day of exposure Day 0 (prior to exposure) and Days 1, 3, 7 and 15. After an observation period of 14 days, the animals were sacrificed and macroscopic examination was performed.

The mean actual concentration was 4.907 mg/L. The nominal concentration was 15.9 mg/L. The mean mass aerodynamic diameter (MMAD) was 3.55 μm and the geometric standard deviation (GSD) was 2.90. No mortality occurred. During and after exposure no clinical signs were noted. In both genders body weight loss was observable on the day of inhalation exposure. In both sexes a compensation of body weight loss was found from the third day of the observation period, but on the basis of body weight and body weight gain data, there was no notable test item effect observable in the exposed animals. There were no test item-related macroscopic findings.

The acute inhalation median lethal concentration (4h LC50) of test item Crystalline calcium silicate hydrates (xonotlite – tobermorite) in Wistar Crl:(WI) BR rats was considered to be higher than 4.907 mg/L. As no deaths occurred the tested concentration can be considered as LC0.

Based on these results Crystalline calcium silicate hydrates (xonotlite – tobermorite) does not have to be classified and has no obligatory labeling requirement for acute inhalation toxicity according to the criteria outlined in Annex I of 1272/2008/EC and Annex VI of 67/548/EEC.

Endpoint conclusion

Dose descriptor:

LC50

Value:

4 907 mg/m³ air

Additional information

An assessment of acute inhalatory toxicity with Crystalline calcium silicate hydrates (xonotlite – tobermorite) in the rat was performed according to OECD Guideline No.403. The test material was administered as an aerosol by inhalation for 4 hours to one group of 5 male and 5 female Wistar Crl:(WI) BR rats to a mean actual concentration of 4.907 mg/L. No mortality occurred. During and after exposure no clinical signs were noted. In both genders body weight loss was observable on the day of inhalation exposure, compensation of body weight loss was found from the third day of the observation period. However, on the basis of body weight and body weight gain data, there was no notable test item effect observable in the exposed animals. There were no test item-related macroscopic findings. The acute inhalation median lethal concentration (4h LC50) of test item Crystalline calcium silicate hydrates (xonotlite – tobermorite) in Wistar Crl:(WI) BR rats was considered to be higher than 4.907 mg/L.

Justification for classification or non-classification

As no deaths occurred at 4.907 mg/L the tested concentration can be considered as LC0. Based on these results Crystalline calcium silicate hydrates (xonotlite – tobermorite) does not have to be classified and has no obligatory labeling requirement for acute inhalation toxicity according to the criteria outlined in Annex I of 1272/2008/EC.