Silicic acid, calcium salt

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

14 - 28 Sep. 1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1981

Report date:

1981

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

The highest attainable exposure concentration was limited for technical reasons.

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Silicon dioxide

EC Number:

231-545-4

EC Name:

Silicon dioxide

Cas Number:

7631-86-9

Molecular formula:

O2Si

IUPAC Name:

dioxosilane

Details on test material:

CAB-O-SIL M5: CAS-Name: Silica, amorphous, fumed, crystalline-free; CAS-No.: 112945-52-5, purity ca. 100 %

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague Dawley, Madison/Wisconsin
- Age at study initiation: "young" (no further data)
- Weight at study initiation: 258 - 297 g (male); 215 - 240 g (female)
- Fasting period before study: no
- Housing: single
- Diet: ad libitum except during exposure
- Water: ad libitum except during exposure
- Acclimation period: >= 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): data not included in the report
- Humidity (%): data not included in the report
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 / 12 hours

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel and glass inhalation chamber
- Exposure chamber volume: total 80 L with dimensions of the central unit of approx. 50 L
[12 inch high, 18 inch wide, 18 inch deep (approx. 30 x 46 x 46 cm)]
- Method of holding animals in test chamber: as group in the chamber cage
- Source and rate of air: from the top center of the chamber, 56 - 85 L/min
- Method of conditioning air:
- System of generating particulates/aerosols: stream of air passed through the test material
contained in a 3-L 3-necked flask equipped with a magnetic stirrer
- Method of particle size determination: using a Delron Cascade Impactor, model No. DCI-6:
Sample collected a approx. one and 3 h into the exposure
- Treatment of exhaust air: collected at the bottom and relaease to outside after dilution
- Temperature, humidity, pressure in air chamber: mean 72.3 °F (room) / mean 76.6 °F (chamber)


TEST ATMOSPHERE
- Brief description of analytical method used: gravimetric - amount of dust collected on glass fiber filter divided by air volume
- Samples taken from breathing zone: yes


TEST ATMOSPHERE (Report Tab. 2 and 3)
- Particle size distribution: based on sample 1 and 2
16 mass% =< 0.325 µm / 0.168 µm
50 mass% =< 0.989 µm / 0.534 µm
83 mass% =< 3.007 µm / 1.698 µm
98.13 and 99.43 mass% =< 10 µm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): MMAD = 0.76 µm / GSD = 3.11


CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: For technical limitations, the highest attainable concentration was applied.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

Analytical concentration: 2.08 mg/L
(average of 10 samples with a range from 1.63 to 2.70 mg/L, one outlier with 0.45 mg/L) (Report Tab. 1)

Nominal concentration:
58.8 mg/L

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: 2x/d / body weight on days 0, 7, and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC0

Effect level:

>= 2.08 mg/L air (analytical)

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.08 mg/L air (analytical)

Exp. duration:

4 h

Effect levels 3

Sex:

male/female

Dose descriptor:

LC0

Effect level:

>= 58.8 mg/L air (nominal)

Exp. duration:

4 h

Effect levels 4

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 58.8 mg/L air (nominal)

Exp. duration:

4 h

Mortality:

no

Clinical signs:

other: Nasal discharge, crusty eyes, alopecia, and crusty nose

Body weight:

no particular findings, normal

Gross pathology:

Discoloration of the lung in one test rat, no other particular findings

Any other information on results incl. tables

No animals died. Nasal discharge during exposure, crusty eyes,crusty nose and alopecia at days post-exposure.
No macroscopic organ lesions, but in one animal discoloration of the lung.
  

Applicant's summary and conclusion

Interpretation of results:

other: non-toxic