Exposed: Pesticides

Whether in food, water or air, current research suggests that no corner of the global environment is spared from pesticide contamination — not even the bacteria and fungi needed to regenerate soil.

Pesticides include popular products such as insecticides, herbicides, fungicides and rodenticides. Many properties and impacts of these chemicals remain unstudied, but researchers are continuing to uncover links to cancer, respiratory diseases and neurological impacts such as altered brain development and Parkinson’s disease. Some pesticides break down into less harmful substances over time, but others, such as DDT, can persist for decades.

Agricultural workers are particularly at risk of the dangers posed by pesticides used to fight off weeds, funguses and insects. Photo courtesy of the U.S. Environmental Protection Agency

Agricultural field crop workers face the most pronounced and long-term risk of harm, but chemicals in products for lawn care, household pest control, flea and tick collars and lice treatment shampoos are also significant sources of exposure. Scientists remain divided on whether residues on food are significant enough to affect health.

Up to a quarter of pesticides sprayed outdoors are carried as far as hundreds of miles away. In samples taken across the country, the U.S. Geological Survey found that pesticides have contributed to pervasive air pollution, and the agency has discovered these chemicals in underground aquifers that supply drinking water.

Pesticides also drain into surface watersheds — in 2014, the USGS estimated that nearly all national waterways contain at least one pesticide, often at levels exceeding federal standards for aquatic life, but rarely considered dangerous to human health. Yet there is scant research on the combined effect of multiple pesticides, so the agency notes “the potential for adverse effects is likely greater than these results indicate.”