Use slowed in the 1970s and stopped in 1988. Heptachlor epoxide is also a white powder and is a breakdown product of heptachlor. The epoxide is more likely to be found in the environment than heptachlor. They stick strongly to soil particles and evaporate slowly to air. Heptachlor epoxide can stay in the soil and water for many years.
Animals change heptachlor to the epoxide Plants can take up heptachlor from the soil.
Levels build up in the tissues of fish and cattle. Heptachlor and heptachlor epoxide are clearly toxic to humans and animals and can damage the nervous system. There are some human data on brief exposures to high levels. A few human case reports showed that people who accidentally swallowed pesticide that contained heptachlor, or who spilled pesticide on their clothes became dizzy, confused, or had convulsions. Most of what we know about the health effects of these pesticides comes from studies on mice and rats fed heptachlor and heptachlor epoxide in the food or water.