Three long-term studies were performed to evaluate the carcinogenic potential of the pesticide rotenone in hamsters and rats. Rotenone was administered orally to Wistar rats and by intraperitoneal injection to Sprague-Dawley rats, which were maintained and observed for 14 and 18 months, respectively. Syrian golden hamsters were maintained for 18 months on diets containing rotenone in concentrations up to 1000 ppm. Following these studies the animals were subjected to extensive necropsy. No evidence of an increased incidence of mammary or any other type of neoplasm was noted in the two rat studies. At all dosage levels in the hamster dietary study, no gross or histopathological evidence was obtained to suggest that rotenone induced the formation of mammary tumors. Three adrenal cortical carcinomas were observed in 65 hamsters from the highest dosage group; while suspicious, it is questionable that this occurrence was related to rotenone treatment. There were no other indications of neoplastic events. In ancillary studies there was preliminary evidence that rotenone at levels of 500 ppm in the maternal diet was embryo-toxic and resulted in cannibalism of the young by the maternal animals. A level of 1000 ppm led to sterility in one or both sexes. Hamsters fed rotenone displayed reduced feed consumption and diminished weight gains during the first few months of administration.

Caption title. "April 1981." "EPA-600/1-81-037." Microfiche.