Agriculture Health Op-Ed Policy Update Research Science

It’s time to put warning labels on Roundup

AFE student Lindsay Gaesser rounds up the arguments for putting warning labels on Roundup, the notorious herbicide that’s often in the news.

To date, three separate juries have ruled that glyphosate caused cancer in California men who were exposed to the herbicide while handling Roundup weed killer. These lawsuits are the first in a wave of more than 18,000 similar cases across the United States, each with plaintiffs alleging that long-term exposure to Roundup caused them to develop cancer and that Monsanto hid the risks associated with the product. While these verdicts are a small piece of the larger battle over whether or not glyphosate is carcinogenic, they present an opportunity for Bayer, Monsanto’s parent company, to do damage control while also keeping the world’s most popular weed killer on the shelves. That is, at least for the time being.

With no available commercial-scale alternatives, Roundup and other glyphosate-based herbicides (GBH) may be a necessary evil in weed control. As such, regulations should instead require agrichemical companies to place health-warning labels on their GBH. Not only would these labels warn consumers that such products are potentially cancer-causing, they may serve as a catalyst that spurs industry efforts to finally develop viable alternatives. Although an outright ban may temper the rising anti-corporate sentiment in society, the full implications of glyphosate elimination are difficult to foresee. One thing is certain—farmers, not agrichemical companies, would bear the brunt of the ban. Because U.S. farmers rely heavily on glyphosate-tolerant GMO crops, a ban would force them to overhaul their approach to weed control. This would be economically and ecologically costly, and it could put some farmers out of business.

Citing its own conclusions that glyphosate does not present a cancer risk, the Environmental Protection Agency stated in August that it will no longer approve California’s glyphosate warning labels. This decision highlights the contentious debate over the safety of glyphosate and the contradictory conclusions of current scientific evidence. Although the International Agency for Research on Cancer (IARC) concluded in 2015 that glyphosate is “probably carcinogenic to humans,” the EPA failed to find a link between glyphosate and cancer. How did these agencies reach such diametrically opposed conclusions? The devil is in the details.

Although the EPA and the IARC did review some of the same studies, the EPA relied mostly on unpublished regulatory studies, some of which were industry-funded, while IARC relied mostly on peer-reviewed studies. The key difference in the agencies’ assessments, however, is that the EPA’s evaluation was largely based on data from studies on technical glyphosate, whereas the IARC placed heavy weight on the results of formulated GBH and aminomethylphosphonic acid (AMPA), glyphosate’s primary metabolite.

This distinction is important because formulated GBH account for all commercial uses and human exposures. No herbicide products contain just glyphosate—the active ingredient is merely one component of a complex chemical formulation. Because many co-formulants are more toxic than technical glyphosate, research suggests that formulated GBH are more toxic than the active ingredient alone. Further, many of the surfactants used in the formulation of GBH are designed to accelerate the movement of glyphosate across plant membranes. While this trait makes Roundup extremely effective at killing weeds, it also fosters the movement of glyphosate into mammalian cells, which is where toxicological responses such as oxidative stress, DNA damage, and cell lesions can occur. When damaged cells proliferate, it can lead to mutations that ultimately cause cancer.

Although scientific evidence is not as strong so as to be absolutely sure whether glyphosate causes cancer, studies from laboratory animals and human populations suggest that current levels of exposure to GBH can induce adverse health outcomes. This should be sufficient to warrant regulations requiring some type of warning label on these products. The EPA disagrees, however, claiming that, in the face of uncertain science, such warnings constitute false and misleading statements. While improved scientific understanding of GBH and their potential hazards is vital in settling the debate over glyphosate, this progress is hindered by the fact that agrichemical companies are only required to disclose active ingredients in herbicides. Under federal law, the full chemical compositions of herbicide formulations qualify as trade secrets. Not knowing the identity or percentage quantity of inactive ingredients makes it difficult for scientists to test the different components and determine toxicity and possible synergistic impacts. Effectively, federal law protects the proprietary information of agrichemical companies at the expense of farmworkers’ health.

While the scientific jury may be out on glyphosate, courtroom juries are not. And with the surge in lawsuits alleging that Roundup causes cancer, it would be unwise and costly for Bayer to leave the fate of glyphosate in the hands of juries who are eager to punish Monsanto for both its negligence and deliberate public deception. In the absence of GBH alternatives, an outright ban is simply unrealistic at present. In the meantime, warning labels are a practical solution that could spur development of GBH alternatives and enable companies to keep their trade secrets, while also working toward improving Roundup’s reputation in the court of public opinion.


Lindsay Gaesser is a second-year AFE student at the Friedman School and has a J.D. from the University of Oregon School of Law. She did her summer internship with the Food Law and Policy Clinic at Harvard Law and currently serves as the communications director for the Future of Food and Nutrition Conference. In her spare time, she enjoys cycling, exploring the outdoors, and sharing good food with good friends.

The Friedman Sprout is a monthly student run newspaper that aims to serve the student population at the Friedman School of Nutrition Science and Policy, prospective students, and alumni. Our mission is to report on newsworthy information that affects the Friedman community including nutrition research, food policy, internship and volunteer opportunities, as well as school events. Our editorial slant is that of sustainability in food and nutrition.

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