There is evidence that heptachlor and heptachlor epoxide are associated with infertility and improper development of offspring. Animal studies have shown that females were less likely to become pregnant when both males and females were fed heptachlor. The Environmental Protection Agency has classified heptachlor and heptachlor epoxide as probable human carcinogens. The liver is the organ which is most sensitive to the acute toxic effects of heptachlor. In mammals, heptachlor is readily converted to its most persistent and toxic metabolite, heptachlor epoxide.
Metabolism occurs in the liver.
Heptachlor epoxide is stored mainly in fatty tissue, but also in liver, kidney and muscle tissues. Twelve weeks after cessation of the exposure, heptachlor disappeared completely from fatty tissues, while heptachlor epoxide was found in the rats' fatty, liver, kidney and muscle tissues. Heptachlor epoxide has also been found to accumulate in the fatty tissues of humans, dogs and chickens. Heptachlor is generally not detectable in the human population, but heptachlor epoxide has been found in human fat, blood, organs and milk. Heptachlor is able to cross the placenta and has been found in human milk.