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EC number: 200-543-5 | CAS number: 62-56-6
Developmental toxicity / teratogenicity
Administrative data
- Endpoint:
- developmental toxicity
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- no data
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: secondary source; the original reference was not available but is cited in the "Concise International Chemical Assessment Document 49-Thiourea" (WHO, 2003); data sufficient for assessment
Data source
Referenceopen allclose all
- Reference Type:
- secondary source
- Title:
- Thiourea. In: Some thyrotropic agents.
- Author:
- IARC
- Year:
- 2 001
- Bibliographic source:
- International Agency for Research on Cancer; IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 79; Some thyrotropic agents; 2001; pp. 703–725
- Reference Type:
- publication
- Title:
- Effects of hypothyroidism on reproductive behaviour in female sheep: clinical studies.
- Author:
- Nasseri, A.A. and Prasad, M.C.
- Year:
- 1 987
- Bibliographic source:
- Indian Vet J 11:191-199
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- In a study in which 66 female sheep (18 growing lambs, 18 maiden ewes, 9 pregnant ewes; controls: 9 growing lambs, 9 maiden ewes, 3 pregnant ewes) were orally administered 0 or 50 mg thiourea/kg body weight daily for 2, 4, or 6 months (six treated and three controls per group)
- GLP compliance:
- not specified
- Limit test:
- yes
Test material
- Reference substance name:
- Thiourea
- EC Number:
- 200-543-5
- EC Name:
- Thiourea
- Cas Number:
- 62-56-6
- Molecular formula:
- CH4N2S
- IUPAC Name:
- thiourea
- Test material form:
- not specified
- Details on test material:
- no details on test material are available
Constituent 1
Test animals
- Species:
- other: lamb
- Strain:
- not specified
- Details on test animals or test system and environmental conditions:
- no data
Administration / exposure
- Route of administration:
- oral: unspecified
- Type of inhalation exposure (if applicable):
- other: not applicable
- Vehicle:
- not specified
- Details on exposure:
- no data
- Analytical verification of doses or concentrations:
- not specified
- Details on analytical verification of doses or concentrations:
- no data
- Details on mating procedure:
- no data
- Duration of treatment / exposure:
- 2, 4, or 6 month
- Frequency of treatment:
- daily
- Duration of test:
- no data
Doses / concentrations
- Remarks:
- Doses / Concentrations:
50 mg/kg bw/day
Basis:
nominal conc.
- No. of animals per sex per dose:
- 6 animals per dose and treated group; 3 animals per control group
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- 66 female sheep (18 growing lambs, 18 maiden ewes, 9 pregnant ewes; controls: 9 growing lambs, 9 maiden ewes, 3 pregnant ewes) were orally administered 0 or 50 mg/kg bw daily for 2, 4, or 6 month
Examinations
- Maternal examinations:
- no data
- Ovaries and uterine content:
- no data
- Fetal examinations:
- no data
- Statistics:
- no data
- Indices:
- no data
- Historical control data:
- no data
Results and discussion
Results: maternal animals
Maternal developmental toxicity
- Details on maternal toxic effects:
- Maternal toxic effects:yes
Details on maternal toxic effects:
- abortion, stillbirth, birth of weak/low-weight lambs, dystokia, and retention of placenta were common features
- external genitalia were infantile and stunted in growing lambs, while they were pale anaemic and dry in maiden ewes
- none of the growing lambs showed signs of estrus
- mammary development was retarded
- the severity of changes was dependent upon the stage of gestation when hypothyroidism was induced
Effect levels (maternal animals)
- Dose descriptor:
- LOEL
- Effect level:
- 50 mg/kg bw/day (nominal)
- Based on:
- test mat.
- Basis for effect level:
- other: maternal toxicity
Results (fetuses)
- Details on embryotoxic / teratogenic effects:
- Embryotoxic / teratogenic effects:yes
Details on embryotoxic / teratogenic effects:
birth of weak/low-weight lambs
Fetal abnormalities
- Abnormalities:
- not specified
Overall developmental toxicity
- Developmental effects observed:
- not specified
Applicant's summary and conclusion
- Conclusions:
- Thourea was shown to developmental toxicity in females at 50 mg/kg bw/day. The severity of changes was dependent upon the stage of gestation when hypothyroidism was induced.
- Executive summary:
66 female sheep (18 growing lambs, 18 maiden ewes, 9 pregnant ewes; controls: 9 growing lambs, 9 maiden ewes, 3 pregnant ewes) were administered orally 0 and 50 mg thiourea/kg body weight daily for 2, 4, or 6 month. External genitalia were infantile and stunted in growing lambs and pale anaemic and dry in maiden ewes. The growing lambs did not show signs of estrus and mammary development was retarded. Thiourea administered to pregnant ewes induced abortion, stillbirth, birth of weak/low-weight lambs, dystokia, and retention of placenta. The severity of changes was dependent upon the stage of gestation when hypothyroidism was induced.
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