Ever since Silent Spring, there have been two major concerns about the environmental impact of pesticides. One is that they may kill birds and other wildlife.The other is that they may be causing cancer and other diseases in humans.

Judging by research, newspaper reports, and legislation, the question of human health rather than the impact on animals is uppermost in people's minds, at least in the United States."Public concern regarding the role of environmental pollutants in causing human cancer remains intense," says Clark W. Heath Jr., writing in the journal Cancer, "and for no specific class of potential pollutant is concern more intense than for chemical pesticides."

Pesticide Poisoning

The most obvious danger to human health from pesticides is through accidental poisonings. But what seems to worry people more is that long-term exposures to extremely small quantities of...