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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: other: micronucleus assay
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No data on the ratio of normochromatic to polychromatic erythrocytes and no positive control were indicated.

Data source

Reference
Reference Type:
publication
Title:
NTP Report on the toxicity studies of cresols in F344/N rats and B6C3F1 mice (feed studies). NTP TOX 9, 1990/1991
Author:
US Department of Health and Human Sevices
Year:
1991
Bibliographic source:
US Department of Health and Human Sevices (1990/1991) NTP TOX 9, 1990/1991

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
not specified
Principles of method if other than guideline:
Smears were prepared from peripheral blood samples obtained by cardiac punction of dosed and control animals at the end of the 13 week study. Polychromatic and normochromatic erythrocytes from each animal were scored for micronuclei.
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male/female

Administration / exposure

Route of administration:
oral: feed
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
Daily
Post exposure period:
No
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 5000, 10000, 20000 ppm
Basis:
nominal in diet
No. of animals per sex per dose:
10
Positive control(s):
No data

Examinations

Tissues and cell types examined:
Erythrocytes from peripheral blood samples.
Details of tissue and slide preparation:
Slides were stained with Hoechst 33258/pyrcein Y according to MacGregor et al (1983).
Evaluation criteria:
Considered as positive result if a significant elevation in the frequency of micronucleated erythrocytes is observed either in males or in females.
Statistics:
yes, however method was not mentioned.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
not specified
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not examined

Any other information on results incl. tables

Significant frequency of micronucleated erythrocytes was not observed in either male or female mice.

The NOAEL value determined for systemic toxicity was 1250 ppm (199 and 237 mg/kg bw/d, respectively) based on increased relative and absolute liver and kidney weights without histopathological correlation from 2500 ppm onwards.

Applicant's summary and conclusion