Perinatal Carcinogenicity Studies

NTP. 1990. NTP Technical report on the perinatal toxicity and carcinogenicity studies on ethylene thiourea in F/344 rats and B6C3F1 mice (feed studies). National Toxicology Program. NTO-TR-388, NIH Pub. No. 90-28-43 (In retrieval). 

A recent study confirmed that ethylene thiourea was carcinogenic in male and female rats as shown by increased incidences of thyroid follicular cell neoplasms after treatment of up to 250 ppm in the diet for 2 years. In mice, concentrations ranging from 100 to 1000 ppm for 2 years caused liver and pituitary tumors in addition to thyroid tumors. Perinatal exposure up to 8 weeks followed by a control diet for 2 years was not carcinogenic in rats or mice. Combined perinatal-adult ETU exposures produced the same carcinogenic effects as adult-only exposures. 

Examination of reproductive function, of embryo-fetal and perinatal toxicity of mutagenic potential and of carcinogenic potential must be considered. However, constituents other than the active substance(s) are incriminated, validation of their removal may replace the study. 

Animal toxicology a summary along with acute, long-term, reproduction, local toxicity and mutagenic/carcinogenic data. There are detailed requirements of toxicity studies in terms of time, dose, route of administration, which are beyond the scope of this article. Reproduction study requirements are also specified in terms of fertility studies, terato-genecity studies and perinatal studies. Local toxicity is limited to preparations intended for topical use. 

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