Pesticide exposure: human cancers on the horizon.

Dichlorodiphenyltrichlorethane, a halogenated hydrocarbon, was introduced as an insecticide in the 1940s. In her book "Silent Spring", Rachel Carson expressed her concern for the environment, plants, animals, and human health about the potential harmful effects of such chemicals. In 1972, the Environmental Protection Agency banned the chemical in the USA. DDT and its metabolite DDE are lipid soluble compounds that persist in the environment and bioaccumulate in the body in adipose tissue at levels far higher than those in blood and breast milk. This paper evaluates the possibility of cancer occurring in humans from DDT exposure. Some risk of lymphoma, leukemia, pancreatic cancer, and breast cancer was found in humans exposed to DDT. Animal studies showed a significant association between DDT administration and lymphoma, respiratory cancer, liver cancer, and estrogenic effects on mammary tissue. On the basis of on epidemiological principles, human studies were deficient in adequate sample sizes and were not exempt from such confounding factors as multiple chemical exposure, lifestyle factors, genetic, and other environmental influences. Extrapolation of data on DDT toxicity from animals to humans has limitations. With the persistence of DDT and DDE in the environment, the potential risk to the health of man, animals, and the environment remains.