2. Relevance to Public Health 2.1 Background and Environmental Exposures to Heptachlor and Heptachlor Epoxide in the United States

Heptachlor is a polychlorinated cyclodiene insecticide that was extensively used prior to 1970 to kill termites, ants, and soil insects in seed grains and on crops. In 1983, the manufacturers voluntarily cancelled its registered uses, with the exception of termite and fire ant control. Currently, the only permitted use of heptachlor is for fire ant control in buried power transformers; however, there are no actively registered pesticides containing heptachlor as an active ingredient. Heptachlor epoxide is the primary degradation product of heptachlor. Heptachlor epoxide is more persistent in the environment than heptachlor and biomagnifies in the terrestrial food chain. Although the use of heptachlor is restricted, exposure to the general population can occur through the ingestion of contaminated food, inhalation of vapors from contaminated soil and water, and dermal contact with contaminated soil and water. The food classes most likely to contain residues are milk and other dairy products, vegetables, meat, fish, and poultry.