What is Chlordane?
Chlordane is a chemical pesticide first synthesized in 1948. It was used across the United States as a crop, lawn, and garden insecticide by both commercial farms and homeowners. Due to concerns over its potential to cause human cancers, chlordane use was restricted by the Environmental Protection Agency (EPA) beginning in 1983.
Also known as chlordan or chlordano, chlordane is a combination of 23 to more than 50 related chemicals. It can range from clear to amber colored and may have no odor at all or may smell something like chlorine. Its most common use was in the treatment of termites inside homes and other buildings, but chlordane was also applied to lawns, gardens, and agricultural fields.
Effect of Chlordane on Wildlife
Chlordane is highly toxic to some animal species and only slightly toxic to others. Animals most dangerously affected by chlordane include:
- Fish
- Bees
- Earthworms
- Freshwater invertebrates
Because the chemical is stored in fatty tissue, it leads to a condition known as ’bioaccumulation.’ As an animal is exposed to chlordane over a period of time, larger and larger amounts of the chemical are stored in its body. If a predatory animal eats a chlordane-affected animal, its own levels of chlordane will rise. The level, therefore, becomes higher in the animals highest on the food chain. Chlordane is not as toxic to these higher life forms, but years of exposure may lead to ill effects. Birds like quail, mallard ducks, and pheasants have been shown to suffer moderate toxicity when exposed to chlordane.
Environmental Impact
Chlordane is a persistent chemical in that it does not break down easily in soil, water, or when exposed to sunlight. Scientists measure the breakdown of a chemical by its half-life, the time it takes half of a given amount to break down. Chlordane’s half-life in soil can range from a short 37 days to a very long 3,500 days (more than nine and a half years).
On the other hand, chlordane is insoluble in water and binds tightly to soil particles, making it an unlikely candidate for groundwater contamination. In cases where chlordane has contaminated drinking water, an accidental spill has occurred. With normal agricultural or domestic use, it’s very unlikely for chlordane to contaminate water supplies.
Effect of Chlordane on Humans
Chlordane is considered moderately toxic to humans if ingested or exposed to skin, while it is considered of low to moderate toxicity if inhaled. Immediate effects of chlordane poisoning include:
- Headache
- Mental confusion
- Nausea
- Vomiting
- Poor balance
- Tremors
- Convulsions
Convulsions may occur immediately or up to 48 hours after chlordane exposure. Chlordane has also been linked to both liver cancer and testicular cancer and is considered a ’probable human carcinogen’ by the EPA. While chlordane has definitely caused cancer in laboratory animals, no studies have been able to prove or disprove the relationship between the chemical and human cancers.
Current Use of Chlordane
Widely used for three decades, chlordane’s slow breakdown in the environment, toxicity to some wildlife, and potential to cause cancer led to massive restrictions and banning by the EPA. Beginning in 1983, chlordane use was limited solely to the treatment of termites in homes, businesses, and other structures. In 1988, the EPA banned that use as well.
As of the first decade of the twenty-first century, the chemical can be used in the United States only to treat termites in power transformers. Despite these restrictions, chlordane is still manufactured in the United States and is sold for use in foreign countries.