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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Meets generally accepted scientific standards, well documented, acceptable for assessment. Read-across to silica aerogel.
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

Constituent 1
Reference substance name:
112926-00-8
EC Number:
601-214-2
Cas Number:
112926-00-8
IUPAC Name:
112926-00-8
Constituent 2
Reference substance name:
silica aerogel
IUPAC Name:
silica aerogel

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 five times at dose levels of 1.4, 14 and 140 mg/kg (Litton Bionetics 1974).

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