Lack of Long-term Effects of the Administration of Heptachlor to Suckling Rats

Abstract

95 Wistar rats were given 5 administrations of 10 mg/kg heptachlor in corn oil each by stomach tube, every second day starting at 10 days of age. Seven animals died before weaning. No early deaths were recorded among 36 controls given corn oil only. 29 experimental animals were killed at 60 weeks of age to detect early changes which were nevertheless absent. Growth and survival rates were similar in experimental and control animals. The incidence of tumors at different sites in males and that of adrenal, thyroid and pituitary tumors in females were comparable in both groups. 9 of 28 treated females developed a total of 12 tumors in various organs (including 5 mammary tumors and 2 renal lipomatous tumors) whereas 4 of 27 control females developed a total of 4 tumors (2 of which were located in the breast). In view of the different locations of the tumors and the lack of the reproducibility of the finding among males the results are not considered as evidence of carcinogenicity of heptachlor under the present experimental conditions.