Fumes, silica

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1974

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

GLP compliance:

no

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

112926-00-8

Cas Number:

112926-00-8

IUPAC Name:

112926-00-8

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

10-12 wk old random-bred rats (weight 280-350 g) were fed commercial 4% fet diet and water ad libitum

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

0,85% saline

Duration of treatment / exposure:

either single administration (acute) or repeated administration (5 times, subacute)

Frequency of treatment:

either single administration (acute) or repeated administration (5 times, subacute)

Post exposure period:

6, 24 and 48 hours after administration (single dose) and 6 hours after last administration (5 doses)

Doses / concentrations

Remarks:

Doses / Concentrations:
1.4, 14.0, 140, 500, 5000
Basis:
nominal conc.
mg/kg

No. of animals per sex per dose:

15 animals per dose group

Control animals:

yes, concurrent vehicle

Positive control(s):

yes, 0.3 mg/kg triethylene melamine

Examinations

Details of tissue and slide preparation:

Bone marrow was retrieved from femur and cell preparations were done.

Evaluation criteria:

The chromosomes of each cell were counted and only diploid cells were analyzed. They were scored for chromatid gaps and breaks,
chromosome gaps and breaks, reunions, cells with greater than ten aberrations, polyploidy, pulverization, and any other chromosomal aberrations which were observed. They were recorded on the currently used forms and expressed as percentages on the summary sheets. Fifty metaphase spreads were scored per animal. Mitotic indices were obtained by counting at least 500 cells and
the ratio of the number of cells in mitosis/the number of cells observed was expressed as the mitotic index.

Statistics:

no data

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

yes

Vehicle controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
Silica gel did not induce bone marrow chromosomal aberrations in rat.

Executive summary:

In a valid cytogenetic assay in rats no chromosomal aberrations were seen in bone-marrow cells treated with silica gel once or 5 times at dose levels of 1.4, 14 and 140 mg/kg (Litton Bionetics 1974).