Pesticides

Topic summary contributed by volunteer(s): Randy

Eight-hundred-million pounds of pesticides are used annually in the United States. Human exposure to pesticides may occur by accident. For example, a 1969 dioxin outbreak resulted from a pipe mix-up at a plant that was producing both pesticides and animal feed. People can also be exposed to pesticides via residues on plant food sources: bamboo shoots imported from China had pesticide contamination levels that were over a suggested safety limit. GMO soybeans have significantly higher pesticide residues than organic or conventional non-GMO soy. Also, some plants may contain fecal viruses due to manure contamination of the water used to spray pesticides on crops.

While some plant foods may be contaminated, animal food intake is the biggest source of certain pesticide exposure for both adults and children. Pesticides, as well as antibiotics, manure, pus cells, cholesterol, and saturated fat have all been found in milk. Factory farmed fish have higher levels of DDT and other banned pesticides than wild-caught fish, and even fish oil supplements may be contaminated with PCBs and insecticides. Many pesticides take a long time to degrade – the U.S. made arsenic-based pesticides illegal years ago, but they still persist in the soil. Similarly, though DDT was banned in the U.S. for agricultural use in 1972, people may still be exposed to the pesticide through contaminated dairy products and meat. 

Most American women have pesticides and other toxins in their bloodstream. Thus is not surprising since even the U.S. Inspector General found that the USDA was not providing adequate protection from pesticide exposure. Luckily, not all pesticides may be connected to health concerns. For example, the Bt toxin produced by the GMO crop known as Bt corn is a pesticide considered so nontoxic that it is sprayed on organic fruits and vegetables. In other cases, we don’t have enough research to definitively know. The pesticide Roundup has been found to be 100 times more toxic than its active ingredient, glyphosate. Still, due to the lack of truly informative human studies, it is unknown to what degree application of Roundup on is harmful to human health, and we have to be aware of conflicts of interest when reading scientific studies.

On the other hand, some pesticides have been more definitively linked to harmful effects on human health. For example, some pesticides may increase the risk of multiple allergic symptoms, male infertility, diabetes, Parkinson’s disease, and cancer.

Consumers often want organic vegetables and fruits to reduce pesticide intake, and indeed, by eating organic, we can reduce our exposure to pesticides, though it remains unclear whether such a reduction in exposure is clinically relevant.  However, if a person cannot get organic produce, the benefits from adequate vegetable and fruit intake may dramatically outweigh any risks of eating conventional produce with residues. Overall, those eating plant-based diets have been found to have a lower levels of pesticides than omnivores. Rinsing produce in a salt water solution may be an effective way to reduce pesticide residues on produce.