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The Glyphosate Debate: EPA Takes Aim At Proposition 65

By Grimaldi Law Associate Jennifer Singh

On August 8, 2019, the U.S. Environmental Protection Agency (EPA) published guidance stating that, under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), it refuses to approve “false and misleading” warning labels on pesticide products that say the chemical glyphosate causes cancer. Glyphosate, the active ingredient in the weed killer, Roundup, is the most widely used herbicide in the United States and is used on more than 100 food crops as well as for various non-agricultural needs. As part of its statement, EPA criticized the International Agency for Research on Cancer’s determination that glyphosate is “probably carcinogenic” and said its own studies have not supported a carcinogenic link.

The agency’s position is in response to, and directly contradicts, California’s Proposition 65 (Prop 65) right to know law. Under Prop 65, the state maintains a list of chemicals shown to cause cancer, including glyphosate, and businesses exposing California consumers to listed chemicals at certain levels are required to provide “clear and reasonable” warnings. When a chemical such as glyphosate is also registered as a pesticide, FIFRA requires manufacturers to submit their labels for EPA’s approval – hence, EPA’s role in taking a position on the incorporation of Prop 65 warnings on pesticide labels.  EPA’s announcement effectively sets up preemption and First Amendment defenses to the imposition of Prop 65’s warning obligations as they pertain to glyphosate.

EPA’s formal decision to prohibit these Prop 65 glyphosate cancer warnings highlights the intense debate over the safety of glyphosate. The dispute spotlights the extreme discrepancies within the scientific community and interest groups at large, and has left regulated industries in a bind: to warn (and how) or not to warn? EPA’s stance also comes in the wake of several multimillion-dollar California jury verdicts against Monsanto, the manufacturer of Roundup, which concluded that Roundup played a substantial role in plaintiffs’ cancer diagnoses. While those verdicts are on appeal, thousands of similar cases are pending at the federal and state level.

Meanwhile, Monsanto also filed its own suit challenging the Prop 65 listing and contingent warning requirements in the U.S. District Court for the Eastern District of California. In February of 2018, the court issued a preliminary injunction stopping the enforcement of Prop 65’s warning requirements for glyphosate until the litigation is resolved. Although that effectively presses pause on the industry’s Prop 65 warning obligations, many universities, cities and counties are taking their own steps to ban the use of glyphosate within their borders. Impacted businesses should remain vigilant about these local and global moving targets as the debate unfolds.


Grimaldi Law Offices has been advising clients for over 20 years on chemical and product regulation. For knowledgeable advice and in-depth analysis on your chemical regulatory compliance obligations, contact Grimaldi Law Offices at (415) 463-5186 or email us at [email protected].

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Ms. Grimaldi maintains a diverse environmental law practice focusing on chemical and product regulation and litigation defense. Her practice areas include Proposition 65, California's Safer Consumer Products Regulations, California's Rigid Plastic Packaging Container Act and the federal Toxic Substances Control Act. Ms. Grimaldi graduated from the University of California Hastings College of the Law magna cum laude and holds a Bachelor of Science Degree in Bacteriology from University of California, Davis. Prior to attending law school, she worked as a research assistant in laboratories at the University of California, San Francisco Cancer Research Institute and at the University of California, San Francisco School of Medicine.