DDT was first developed as an insecticide in the 1940s, and it was widely used during World War II to combat insect-borne diseases, such as malaria and typhus. After the war, DDT’s effectiveness, persistence, and low cost made it popular for agricultural and commercial uses. In 1959, at the height of its popularity, 80 million pounds of the chemical were applied to forests, fields, and gardens (EPA 1972). Over DDT’s 30-year history in the United States, more than a billion pounds were used (EPA 1975).

EPA banned nearly all domestic uses of DDT in 1972. Today, its use is limited to malaria control programs in some developing countries. But most of us are exposed to DDT every day because it is in so much of the food we eat (USDA 2006). Vegetables, meat, fish, and dairy products all contain DDT, but animal and fatty foods contain the highest levels because the chemical is stored in fat and increases in concentration as it moves up the food chain (ATSDR 2002). Children, breastfeeding infants, and people living in the eastern Arctic have the greatest ongoing exposures to DDT from food.

Exposure to DDT is harmful to the nervous system, with high levels causing dizziness, tremor, irritability, and convulsions (ATSDR 2002). Animal studies have found that low levels can affect nervous system development. In addition, people who applied DDT in occupational settings have suffered lasting neurological problems, performing tasks more slowly and displaying delayed reaction times, less dexterity and strength, and reduced cognitive function (van Wendel de Joode 2001).

DDT is also considered a hormone disrupting chemical because of its estrogen-like properties, and researchers have found disturbing effects in this regard. Mothers with greater exposure to DDT are more likely to have premature or small-for-gestational-age babies than mothers less exposed to the chemical (Longnecker 2001). Mothers with more DDT also breastfeed for a shorter period, possibly because DDT mimics hormones that inhibit milk production (ATSDR 2002). Animal studies have found that DDT causes cancer, and EPA ranks DDT as a probable human carcinogen.

Figure 7:  DDT exposure was measured as the breakdown product p,p’DDE in blood serum.