Summary

DDT (dichlorodiphenyltrichloroethane) is a pesticide that was widely used in the mid-20th century to control insect populations. DDT was widely discovered during World War II, where it was used to clear South Pacific Islands of malaria-causing insects for stationed U.S troops, which earned Paul Hermann Müller, its inventor, a Nobel prize. Unlike most pesticides, whose effectiveness is limited to destroying one or two types of insects, DDT was capable of killing hundreds of different kinds at once. DDT became available for wider use in 1945, and in 1962 several scientists and ecologists started to raise the alarm.
The claims were that DDT entered the food chain and accumulated in the fatty tissues of animals, including human beings, and caused cancer and genetic damage. A single application on a crop killed insects for weeks and months—not only the targeted insects but countless more—and remained toxic in the environment even after it was diluted by rainwater. DDT was eventually banned in 1972.

Today, the CDC states that human health effects from DDT at low environmental doses are "unknown". However, following exposure to high doses, DDT could be a possible human carcinogen. Further laboratory animal studies show DDT exposure can also cause liver tumors and negatively affect reproduction.

Intended Positives

It was intended to control insect populations and protect crops from insect damage.

Known or Announced Negatives

DDT has been linked to a variety of negative health and environmental effects, including cancer, reproductive and developmental harm, and damage to ecosystems. It was banned for most uses in the United States in 1972 and by many countries in the world due to its negative effects.

Observed Positives

It was effective in controlling insect populations and protecting crops from insect damage when it was used, and saved many lives from malaria and other insect-borne diseases.

Observed Negatives

DDT has been linked to a variety of negative health and environmental effects, including cancer, reproductive and developmental harm, and damage to ecosystems. Some research studies have shown health problems linked to DDT have persisted across at least three generations, affecting even the granddaughters of women exposed to the chemical in the 1960s. Daughters of the women who had more DDT in their blood had a much heightened risk for breast cancer and increased prevalence of obesity, while sons had heightened risks for testicular cancer. 

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