For related articles and more information, please visit OCA’s Health Issues page and our Food Safety Research Center page.

Beyond Pesticides

New research concludes that exposure to a combination of both arsenic and estrogen, at levels the U.S. Environmental Protection Agency (EPA) considers “safe” for humans, can cause cancer in prostate cells. Texas Tech University researchers revealed that humans exposed to a combination of both toxicants were almost twice as likely to develop cancerous cells in their prostate. The study is published in the peer-reviewed journal
The Prostate.

While it is established that both arsenic and estrogen can cause cancer, the research raises concerns about the dangers of chemicals in combination, and the efficacy of regulations that are established by testing one chemical at a time. Kamaleshwar Singh, PhD, is an assistant professor at The Institute of Environmental and Human Health at Texas Tech. “The majority of cancers are caused by environmental influences,” Dr. Singh remarked to
Texas Tech Today, “Only about 5 to 10 percent of cancers are due to genetic predisposition. Science has looked at these chemicals, such as arsenic, and tested them in a lab to find the amounts that may cause cancer. But that’s just a single chemical in a single test. In the real world, we are getting exposed to many chemicals at once.”

The study contributes to the growing body of research on the interactive effects of pesticides on human health and the environment. For example, Tyrone Hayes, Ph.D., professor of integrative biology at University of California, Berkeley, conducted research on the interactive effects of atrazine and other pesticides in a study on frogs. His study compared the impact of exposure to realistic combinations of small concentrations of corn pesticides on on frog metamorphosis, concluding that frog tadpoles exposed to mixtures of pesticides took longer to metamorphose to adults and were smaller at metamorphosis than those exposed to single pesticides, with consequences for frog survival. The study revealed that “estimating ecological risk and the impact of pesticides on amphibians using studies that examine only single pesticides at high concentrations may lead to gross underestimations of the role of pesticides in amphibian declines.”

Pesticide products available for sale are often chemical mixtures of active ingredients that create a cocktail of toxins, even though studies on pesticide combinations have demonstrated neurological, endocrine and immune effects at low doses. For example, research conducted by Warren Porter, Ph.D., professor of zoology and environmental toxicology at the University of Wisconsin, Madison, examined the effect of fetal exposures to a mixture of 2,4-D, mecoprop and dicamba exposure-frequently used together in lawn products like Weed B Gone Max or and Trillion-on the mother’s ability to successfully bring young to birth and weaning. Researchers began by testing pesticide concentrations diluted to levels that are considered “safe” by the EPA. The results were striking: Dr. Porter found that “this common lawn pesticide mixture is capable of inducing abortions and resorptions of fetuses at very low parts per billion. The greatest effect was at the lowest dose.” Dr. Porter’s work,
Facing Scientific Realities, Debunking the ‘Dose Makes the Poison’ Myth, published in
Pesticides and You, provides more information.