o-cresol

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)

GLP compliance:

yes

Type of assay:

rodent dominant lethal assay

Test material

Test material information

Constituent 1

Reference substance name:

o-cresol

EC Number:

202-423-8

EC Name:

o-cresol

Cas Number:

95-48-7

Molecular formula:

C7H8O

IUPAC Name:

o-cresol

Details on test material:

Test substance: o-cresol, purity: 99.7 %

Test animals

Species:

mouse

Strain:

ICR

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMAL
- Age at study initiation: 8 weeks
- Assigned to test groups randomly: yes
- Housing: males : individually females: in groups
- Diet : ad libitum
- Water : ad libitum
- Acclimation period: 4 days
-body weights at initialtion and at termination of the assay

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 25
- Humidity (%): 50
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

no further data

Duration of treatment / exposure:

once

Frequency of treatment:

once

Post exposure period:

6 weeks

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 75, 250, 750 mg/kg bw in corn oil
Basis:
actual ingested

No. of animals per sex per dose:

25 males per dose.

Control animals:

yes, concurrent vehicle

Positive control(s):

Triethylenemelamine
- Justification for choice of positive control(s):
- Route of administration: single i.p. injection
- Doses / concentrations: 0.3 mg/kg as a volume of 10 ml/kg,

Examinations

Tissues and cell types examined:

All females were examined for the number of live and dead implants within the uterine horn and whether the dead implants had occurred early or late in gestation. Live fetuses were identified as those which appeared to have a functional circulatory capacity.

Details of tissue and slide preparation:

no data

Evaluation criteria:

Statistically significant dose-related increase in the number of dominant leathals is considered as mutagenic in this system.

Statistics:

Chi-square test, ANOVA, Dunnett's one-tailed t test.

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

not specified

Remarks:

concentrations were chosen based on dose-range toxicity study

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

see section : "Remarks on results"

Any other information on results incl. tables

--high dose males:
Mortality: 8/25 within 6 days post dosing.
Signs of intoxication: lethary, rough haircoat, languid, tremor, distended abdomen, squinted eyes; all surviving males recovered from these effects within 6 days after dosing.
No effects were observed on fertility index, total implants, mean implants per pregnant female, total live implants, total dead implants, and body weight gain of males.
The test article was considered negative for inducing dominant lethal mutations in germ cells of male mice under conditions of this assay.

Applicant's summary and conclusion

Conclusions:

The test article was considered negative for inducing dominant lethal mutations in germ cells of male mice under conditions of this assay.

Executive summary:

The test article was considered negative for inducing dominant lethal mutations in germ cells of male mice under conditions of this assay.