Pesticides and herbicides are widely utilized in agricultural settings and individual households throughout the world, use of these chemicals ensures exposure from a variety of sources, including residues in food and water, applications to public spaces, garden and lawn use; and, for some, occupational exposures. Given the widespread use of pesticides and herbicides and the fact that health and environmental effects associated with these chemicals are still being discovered, erring on the side of caution may be the only way to minimize the damage caused by these chemicals.
Humans are exposed to a complex mixture of compounds over a lifetime and human susceptibility varies in ways that may never be completely understood. Environmentally, overuse of the herbicides and pesticides, most recently, the herbicide glyphosate has resulted in the evolution of resistant weeds, which threaten the long-term sustainability of corn, soybeans, canola, and other crops that have been genetically engineered to tolerate glyphosate. In a statement released yesterday, the nonprofit Center for Science in the Public Interest is calling on the Environmental Protection Agency (EPA), which regulates the herbicides sprayed on those engineered crops, to limit use of glyphosate and adopt other measures to slow the spread of resistant weeds.
To prevent public harm from exposures to pesticides and herbicides, the United States EPA and other regulatory bodies require pre-market toxicological testing in laboratory animals. However, the adequacy of this approach can be questioned because toxicological testing is based on the relatively short-term administration of a single active ingredient to inbred strains of animals, While animal testing provides a screening tool to keep many dangerous products off the market, the question remains: Do the products that pass these regulatory hurdles still affect human health and the natural order of the environment?
Farmers planted 170 million acres of genetically engineered crops in 2012. About 154 million acres of that was planted with crops that can tolerate herbicides, the vast majority to Roundup or other brands of glyphosate. Farmers are increasingly dealing with weeds that are not killed by glyphosate, to remedy the resistant weed problem, they are applying more harmful herbicides, negating much of the technology’s touted benefit. Herbicide-resistant weeds are becoming more of a problem, forcing growers to alter their weed-control programs. DuPont Pioneer agronomists say management decisions, such as improved herbicide choices, clean seedbeds and careful planning for harvest, can help decrease resistant weeds.
In a letter to the EPA’s Office of Chemical Safety and Pollution Prevention, CSPI says that the agency should limit farmers’ use of glyphosate, especially in geographic areas where resistant weeds are becoming a problem. Non-chemical weed management techniques such as crop rotation and cover crops will continue to be underutilized without EPA involvement, CSPI says. The letter further points out that the EPA instituted similar requirements to protect the effectiveness of crops engineered to produce a natural insecticide, BT. CSPI also urged the EPA to take steps to reduce the likelihood of weeds developing resistance to other major herbicides, such as 2,4-D and dicamba. That’s because, according to CSPI, in 2013 the U.S. Department of Agriculture likely will approve new genetically engineered crops designed to tolerate application of those chemicals, and farmers may begin planting them by 2014.
Individuals may be exposed to pesticides and herbicides through both direct and indirect routes. Direct exposure occurs to individuals who personally apply pesticides in agricultural, occupational, or residential settings and is likely to result in the highest levels of exposure, whereas indirect exposures occur through drinking water, air, dust, and food and represent routes of long-term, generally low-level exposures. Indirect exposures may occur more frequently than direct pesticide application.