WESTMINSTER, CO. — The board of directors of the Weed Science Society of America (WSSA) issued a statement supporting the U.S. Environmental Protection Agency’s (EPA) science-based approach to evaluating glyphosate — a herbicide that has been the focus of recent lawsuits by those concerned that it may be carcinogenic.

Glyphosate is a uniquely effective and generally nonselective herbicide with a wide range of uses in both agricultural and nonagricultural settings. It has been widely adopted in conjunction with glyphosate-resistant (‘Roundup Ready’) crops, and is also commonly used to manage weeds in conservation tillage crop production, resulting in significant soil improvement and savings. Glyphosate is used in orchards and vineyards, aquatic settings, fallow and noncrop fields, and around homes and gardens. Because of its effectiveness and other desirable characteristics, glyphosate has become the most widely used synthetic herbicide in human history.

In 2015, glyphosate was classified as a “probable carcinogen” by the International Agency for Research on Cancer (IARC). IARC has applied the same classification to red meat, hot beverages, and emissions from high-temperature frying, as well as to more than 70 other chemicals. This designation has caused widespread public concern about the safety of glyphosate while being the recent focus of multiple lawsuits.

Although WSSA members are not experts in human toxicology and epidemiology, we appreciate the rigorous, transparent, and risk-based review process undertaken by the U.S. Environmental Protection Agency (EPA) as mandated by the Food Quality Protection Act (FQPA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). These statutes specify that when setting exposure tolerances, any proposed use of a pesticide should provide a “reasonable certainty of no harm” and that using the pesticide as directed “will not generally cause unreasonable adverse effects” to humans or the environment. FIFRA states that when considering these risks, the EPA must consider “the economic, social, and environmental costs and benefits of the use of any pesticide.” The EPA review process is substantially broader in scope than the more limited hazard-based assessment conducted by IARC.

After reviewing the best evidence available, regulatory bodies around the world have consistently concluded that glyphosate-based herbicides are not likely to be carcinogenic. These agencies include the U.S. Environmental Protection Agency (EPA), the Canadian Pest Management Regulatory Agency, and the European Food Safety Authority (EFSA). Additionally, an independent 2018 Agricultural Health Study supported by U.S. National Cancer Institute found no association between glyphosate-based herbicides and cancer. That conclusion was drawn by researchers who followed the health of more than 50,000 licensed pesticide applicators over more than 20 years.

As part of its standard periodic assessment of previously registered herbicides, the EPA issued a proposed interim registration review decision on glyphosate in April 2019 (Case Number 0178). EPA reiterated that glyphosate is ”not likely to be carcinogenic to humans” and that “[t]he EPA thoroughly assessed risks to humans from exposure to glyphosate from all uses and all routes of exposure and did not identify any risks of concern.”

Extensive reliance on any single tool or technology can be cause for concern. As scientists and weed managers, our membership encourages diversification of weed management practices, including both chemical and nonchemical controls. For that reason, reducing the heavy reliance on glyphosate for weed control is certainly a desirable long-term outcome.

If, though, glyphosate is banned by policy or public outcry, other tools will be used to manage weeds, and many come with their own potential for negative impacts on health and the environment. 

Prohibiting glyphosate use may also result in less effective weed control that could lead to reduced crop yields and quality, buildup of weed seed banks, weed-clogged waterways, degraded wildlife habitats, risks to human and animal health from toxic weed species. It is possible that labor costs may go up and that tillage may increase along with fossil fuel use and soil erosion. In addition, hand-labor can carry the very real risk of musculoskeletal injuries and of skin cancer from overexposure to the sun.

The WSSA supports the scientific evaluation conducted by EPA to determine the safety of properly applied pesticides. When determining whether to allow or discontinue use of any pesticide, it is important to not only weigh the costs and benefits of that pesticide, but also to understand the risks and benefits of the most likely alternatives. Decisions related to glyphosate use are no different. Ongoing research and evaluation are justified, and our society will remain current on further developments related to carcinogenic risk and glyphosate as new information becomes available.

About the Weed Science Society of America 

The Weed Science Society of America, a nonprofit scientific society, was founded in 1956 to encourage and promote the development of knowledge concerning weeds and their impact on the environment. The Society promotes research, education and extension outreach activities related to weeds, provides science-based information to the public and policy makers, fosters awareness of weeds and their impact on managed and natural ecosystems, and promotes cooperation among weed science organizations across the nation and around the world.  For more information, visit www.wssa.net.