DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is a white, crystalline solid with no odor or taste. DDT was manufactured to control insects on agricultural crops and insects that carry diseases like malaria and typhus. It does not occur naturally in the environment. Because of damage to wildlife and the potential harm to human health, the production and use of DDT was banned in the United States, except for during public health emergencies. DDT is still used in some other countries.
DDT breaks down into two similar products: DDE (1,1-dichloro-2,2-bis(chlorophenyl) ethylene) and DDD (1,1-dichloro-2,2-bis(p-chlorophenyl) ethane).
Other names for DDT are Anofex, Cesarex, Chlorophenothane, Dedelo, p, p-DDT, Dinocide, Genitox, Gyron, Hildit, Ixodex, Pentachlorin, and Zerdane.
In air, half the DDT is gone within 2 days. It does not dissolve easily in water. DDT sticks strongly to soil particles and does not move quickly to underground water. DDT lasts a very long time in soil. Half the DDT in soil will break down in 215 years. Some DDT will evaporate from soil and surface water into the air, and some is broken down by sunlight or by microscopic plants or animals in soil or surface water. DDT in soil usually breaks down to form DDE or DDD.
DDT builds up in plants and in the fatty tissues of fish, birds, and animals. When humans eat these plants and animals, they take up and store the DDT and its breakdown products in their fatty tissues. Tissue storages of DDE in the general population originate almost entirely from dietary DDE rather than DDT conversion.
- Eating food is the primary source of exposure for the general population
- Eating foods such as root and leafy vegetables, fatty meat, fish, and poultry
- Eating imported foods from countries that still allow the use of DDT to control pests
- Breathing contaminated air or drinking contaminated water
- Skin contact with contaminated soil surfaces
- Nursing on human breast milk from mothers who have been exposed
DDT and DDE mostly affect the nervous system. Early signs of poisoning include changes of the feeling in the face, hands, and feet, headache, dizziness, nausea, vomiting, incoordination, and tremors. More severe poisonings cause seizures and possibly coma. When exposure stops, these effects get lower.
People who worked with DDT for a long time had some changes in the levels of liver enzymes, but these improved after exposure stopped.
In animals, short-term exposure to large amounts of DDT in food harmed the nervous system, and long-term exposure harmed the liver. Studies in lab animals also showed that short-term exposure to DDT in food might harm reproduction.
DDT and DDE could possibly cause cancer in humans. This is based on several studies in animals and humans.
Liver cancer occurred in lab mice that were fed large amounts of DDT.
Some studies in humans linked DDT levels in the body with breast cancer, but other studies have not made this link. Other studies in humans have linked exposure to DDT/DDE with having lymphoma, leukemia, and pancreatic cancer. No definitive association with these cancers has been made.
Workers heavily exposed to DDT have not had more cancer than workers not exposed to DDT.