What is heptachlor?

Heptachlor is an insecticide that was used in homes and buildings and applied to food crops until 1988.[1] The EPA classifies it as a probable human carcinogen.[2]

Where is heptachlor found?

Heptachlor is still found in the soil. It binds to soil particles and takes years to evaporate into the air. Plants in the contaminated soil can absorb the chemical.[3] Animals eating these plants can also take in the chemical. The most common contaminated foods include fish, shellfish, dairy products, meat and poultry. Heptachlor can also be found in the air and soil near toxic waste disposal sites.[4]

What evidence links heptachlor to breast cancer?

The research regarding heptachlor exposure and cancer in humans is largely inconclusive. There is, however, sufficient research showing its toxicity in animals.

• Heptachlor was used extensively on pineapple crops in Hawaii. Between 1970 and 1985, breast cancer rates among women in Hawaii dramatically increased. Researchers posit that there may be a link between this heptachlor use and breast cancer incidence.[5]
• One study with rats showed that heptachlor caused DNA damage contributing to the development of mammary cancer.[6]
• In rats, heptachlor was found to accumulate in fatty tissue such as mammary tissue.[7]
• Heptachlor exposure caused liver cancer in rats. This impacted the liver’s ability to process hormones, resulting in increased estrogen levels.[8] An excess of estrogen can increase the risk of breast cancer.[9]

Who is most likely to be exposed to heptachlor?

Workers who used heptachlor in the past are most likely to be exposed.[10] Additionally, infants and children have the potential to be exposed through contaminated breast milk or milk from contaminated cows.[11]

Who is most vulnerable to the health effects?

Infants and young children are vulnerable as they may be more sensitive to heptachlor.[12] Fetuses may also be susceptible to exposure, as heptachlor can be transferred through the placenta.[13]

What are the top tips to avoid exposure?

• Wear well-fitting protective clothing, including gloves and a respirator, in areas with high heptachlor concentration such as hazardous waste sites.[14]
• Do not allow children to play in contaminated soil.[15]

Reviewed 2019