Dieldrin

Dieldrin is an organochloride originally produced in 1948 by J. Hyman & Co, Denver, as an insecticide. Dieldrin is closely related to aldicarb, and aldrin, which readily breaks down to form dieldrin. Aldrin is not toxic to insects; it is oxidized in the insect to form dieldrin which is the active compound. Both dieldrin and aldrin are named after the Diels-Alder reaction which is used to form aldrin from a mixture of norbornadiene and hexachlorocyclopentadiene.

History

Originally developed in the 1940s as an alternative to DDT, dieldrin proved to be a highly effective insecticide and was very widely used during the 1950s to early 1970s. Endrin is a stereoisomer of dieldrin.

However, it is extremely persistent in the environment and also exhibits bioaccumulation. Due to its high toxicity toward fish and birds, it was banned in many countries in the 1970s, although its use continued in the Soviet Union until 1989. It has been linked to health problems such as Parkinson's, breast cancer, and immune, reproductive, and nervous system damage. It is also an endocrine disruptor, acting as an estrogen and antiandrogen, and was banned globally by the Stockholm Convention on Persistent Organic Pollutants in 2001.

Chemical Structure

Dieldrin is a chlorinated hydrocarbon used as an insecticide, similar in structure to aldrin. It is a colorless, crystalline solid with a mild chemical odor. It is not soluble in water, but is highly soluble in fats. It is resistant to burning and is not likely to react with other substances.

Health Effects

Exposure to dieldrin can occur through the skin, by breathing it in, or by swallowing it. Dieldrin can increase the risk of cancer. It has been shown to cause lung, adrenal, and liver tumors in rats. It may also affect the immune system, increasing the risk of infection and disease.

Environmental Impact

Dieldrin is highly toxic to fish and other aquatic life. It is also toxic to birds and many other animals. It does not break down easily in the environment and can remain present for many years. It can also build up in the bodies of animals that eat contaminated food.

Regulation

In the United States, the Environmental Protection Agency (EPA) has set a limit of 0.2 parts per billion (ppb) for dieldrin in drinking water. The Occupational Safety and Health Administration (OSHA) has set a limit of 0.25 milligrams per cubic meter (mg/m³) for workplace air during an 8-hour workday, 40-hour workweek.

See Also

• Aldrin
• Endrin
• DDT
• Organochloride
• Persistent Organic Pollutants

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