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Chlordane risks

My wife and I recently bought a wood home (built in 1919). About twenty years ago, it was treated for termite infestation with chlordane. We now hear that chlordane is no longer used. Should we worry about its presence in our home?

—Karl Jacoby, Providence, RI

Chlordane has been banned for all uses in the United States since 1988; however, manufacture for export still continues. According to the Agency for Toxic Substances and Disease Registry, chlordane was used as a pesticide on agricultural crops, lawns, and gardens and as a fumigating agent in the United States from 1948 to 1988. Chlordane is bioaccumulative (it builds up in our food chain) and remains in our food supply because of its use on crops in the 1960s and 1970s.

Because of cancer risk, evidence of buildup in human body fat, persistence in the environment, and danger to wildlife, the U.S. Environmental Protection Agency prohibited chlordane use on food crops and phased out other above-ground uses between 1983 and 1988. During those years, the only approved use was around home foundations to control termites.

Chlordane breaks down very slowly and can remain in soil for more than twenty years. It has been shown to persist in the air of some homes that were treated thirty to forty years ago.

Chlordane can enter the body through the lungs and through skin contact with contaminated soils. Most of it leaves the body in a few days, but chlordane can also be stored in body fat. Chlordane and its breakdown products in blood and fat can be measured as an indication of exposure.

Chlordane affects the nervous system, the digestive system, the endocrine system, and the liver. Breathing air containing high concentrations of chlordane vapors can cause headaches, irritation, confusion, weakness, and vision problems, as well as upset stomach, vomiting, stomach cramps, diarrhea, and jaundice.

A simple soil test will reveal if chlordane may be affecting the indoor air quality of your home. Your local health department will have a list of qualified laboratories. If you discover that your basement or crawl space has a contaminated soil floor, consider removing the soil and installing concrete and/or using vents or fans to exhaust the contaminated air, especially if the basement is part of the return air supply system. Chlordane that was applied in a broadcast fashion might have come into contact with the wood structure; in this case, consider sealing any interior wood to prevent further outgassing into your home.