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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: gene mutation
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well documented and scientifically acceptable

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995

Materials and methods

Principles of method if other than guideline:
Micronucleus cytogenetic assay in mice with thymol (Nr. 259, CAS 89-83-8)
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
purity: 99.7%

Test animals

Species:
mouse
Strain:
ICR
Sex:
male/female

Administration / exposure

Route of administration:
oral: gavage
Duration of treatment / exposure:
single treatment
Frequency of treatment:
single treatment
Post exposure period:
bone marrow cells were collected 24 hours after treatment for all dose levels and at 16 and 48 hours after treatment with 1100 mg7kg
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 275, 550 or 1100 m/kg bw
Basis:
nominal conc.
No. of animals per sex per dose:
5 males and 5 females
Control animals:
yes, concurrent vehicle

Examinations

Tissues and cell types examined:
bone marrow cells were examined for for micronucleated polychromatic erythrocytes

Results and discussion

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

Any other information on results incl. tables

Slight reductions in the ratio of polychromatic erythrocytes to total erythrocytes were observed relative to the vehicle control in high dose male and female mice. These reductions suggest bioavailability of the test article to the bone marrow target. The number of micronucleated polychromatic erythrocytes per 1000 polychromatic erythrocytes was not statistically increased relative to their respective vehicle controls in either males or females, regardless of dose level or bone marrow collection time (p > 0.05).

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Executive summary:

Male and female ICR mice were exposed to 275, 550 or 1100 mg/kg body weight of thymol which was administered in a total volume of 20 mg/kg as a single oral gavage. The high dose level was calculated to be approximately the maximum tolerated dose as per the protocol. Olive oil was used as the test article vehicle. Mortality was observed in 2/20 male and 3/20 female mice receiving 1100 mg/kg. clinical signs following dose administration included lethargy in male and female mice at 275 and 550 mg/kg; lethargy and prostration in male and female mice at 1100 mg/kg. Bone marrow cells were examined for for micronucleated polychromatic erythrocytes.

Slight reductions in the ratio of polychromatic erythrocytes to total erythrocytes were observed relative to the vehicle control in high dose male and female mice. These reductions suggest bioavailability of the test article to the bone marrow target. The number of micronucleated polychromatic erythrocytes per 1000 polychromatic erythrocytes was not statistically increased relative to their respective vehicle controls in either males or females, regardless of dose level or bone marrow collection time (p > 0.05).

The results of the assay indicate that under the conditions described in this report, thymol did not induce a significant increase in micronucleated polychromatic erythrocytes in either male or female ICR mice and was concluded to be negative in the mouse micronucleus assay.