Thymol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: OECD combined repeat dose and reproductive/developmental toxicity screening test

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1996

Materials and methods

Principles of method if other than guideline:

Thymol was studied for oral toxicity in rats in an OECD combined repeat dose and reproductive/developmental toxicity screening test at doses of 0 (vehicle), 8, 40, 200 mg/kg day.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Thymol

EC Number:

201-944-8

EC Name:

Thymol

Cas Number:

89-83-8

Molecular formula:

C10H14O

IUPAC Name:

5-methyl-2-(propan-2-yl)phenol

Test material form:

solid

Test animals

Species:

rat

Strain:

other: Crj:CD (SD)

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 3% gum arabic solution

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

no data

Duration of treatment / exposure:

males: 43 days
females: from 14 days before mating to day 3 of lactation

Frequency of treatment:

daily

Duration of test:

terminal kill:
males: 44 days
females: day 4 of lactation

No. of animals per sex per dose:

10 males + 10 females/group

Control animals:

yes, concurrent vehicle

Results and discussion

Results: maternal animals

Effect levels (maternal animals)

1

Dose descriptor:

NOEL

Effect level:

200 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Remarks on result:

not determinable due to absence of adverse toxic effects

2

Dose descriptor:

NOEL

Effect level:

200 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Remarks on result:

other: see 'Remarks'

Remarks:

The compound exerted no effects on reproductive parameters such as the estrous cycle, mating index, fertility index, gestation lenght, number of corpora lutea or implatations, the implantation index, gestation index, delivery index, parturition or maternal behaviour. Birth weight and body weight gain tended to be low in the 200 mg/kg group neonates. There were no significant differences in numbers of offspring or live offspring at birth, the sex ratio, live birth index or viability index.

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Effect levels (fetuses)

Dose descriptor:

NOEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No abnormal findings ascribable to the compound were found on external examination, or in terms of clinical signs or necropsy finding for the neonates.

Remarks on result:

not determinable due to absence of adverse toxic effects

Fetal abnormalities

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Any other information on results incl. tables

The compound exerted no effects on reproductive parameters such as the estrous cycle, mating index, fertility index, gestation lenght, number of corpora lutea or implatations, the implantation index, gestation index, delivery index, parturition or maternal behaviour. Birth weight and body weight gain tended to be low in the 200 mg/kg group neonates. There were no significant differences in numbers of offspring or live offspring at birth, the sex ratio, live birth index or viability index.

Applicant's summary and conclusion

Executive summary:

Thymol was studied for oral toxicity in rats in an OECD combined repeat dose and reproductive/developmental toxicity screening test at doses of 0 (vehicle), 8, 40, 200 mg/kg day.

The compound exerted no effects on reproductive parameters such as the estrous cycle, mating index, fertility index, gestation lenght, number of corpora lutea or implatations, the implantation index, gestation index, delivery index, parturition or maternal behaviour. Birth weight and body weight gain tended to be low in the 200 mg/kg group neonates. There were no significant differences in numbers of offspring or live offspring at birth, the sex ratio, live birth index or viability index. No abnormal findings ascribable to the compound were found on external examination, or in terms of clinical signs or necropsy finding for the neonates.