A Round-up of Roundup: Recapping Glyphosate Safety

Last month, Bayer (formerly Monsanto), the manufacturers of the herbicide Roundup, asked the US 9th Circuit Court of Appeals to overturn an order that the company pay $25 million in damages to a California cancer patient. Bayer has some big-name supporters, too: the EPA and the Department of Justice. In a brief they filed with the court, the EPA reiterated their position that glyphosate, the active ingredient in Roundup, does not cause cancer in humans. This position is at odds with the research that allowed these cases to come to trial in the first place — an assessment from the WHO that labeled it a “probable human carcinogen.” Based on this evidence, the initial verdict declared that not only was Monsanto liable for the cancer, but that they acted deliberately and maliciously to conceal the risk of cancer from consumers. In spite of this clear effort to mislead the public, Bayer-Monsanto now insists they couldn’t have warned the public about a cancer risk, since labeling their product as dangerous would have been an illegal contradiction of the EPA’s findings. If their argument succeeds, they could get that case — and all others like it — thrown out.

So where does the science on Roundup actually sit, how did it get so contentious, and what does this mean for legal battles ahead?

How Did We Get Here? Glyphosate’s Origins

Glyphosate is an undeniably useful chemical for farmers: it’s broad-spectrum, which means it tackles a wide variety of weeds, and it’s systemic, which means that it moves from the leaves into the roots to kill entire plants. At the time of its introduction in 1974, Roundup looked relatively safe — especially compared to alternatives, it didn’t show acute toxicity to people and animals, and was less likely to drift off-target and kill other plants. The fact that glyphosate damaged all kinds of plants meant its use was initially limited to the edges of fields where it couldn’t hurt crops — it was used sparingly. This changed when Monsanto registered the first Roundup-resistant soybean in 1996. The genetic modification that allows soybeans to tolerate the chemical meant that farmers could spray whole fields with glyphosate, eliminating weeds and leaving their crops unscathed. With the subsequent introduction of Roundup-resistant corn and other crops, glyphosate quickly became the most widely used herbicide in the world, with US usage jumping from 27 million pounds in 1995 to over 249 million pounds in 2014. Today, over 90% of corn and soy seeds in the country are glyphosate-resistant. Glyphosate’s use has expanded outside of just weed-killing, too: farmers of wheat and oats will often spray their crops with glyphosate to speed up drying and harvest at the end of the season.

Glyphosate and Public Health

The notion that glyphosate is a safe chemical for humans — farmworkers and consumers — is also under scrutiny. The EPA review process for pesticides focuses on the primary active ingredient on a short time scale, and from this frame, glyphosate looks pretty good; its LD50 — a common measure of acute toxicity — is similar to table salt. The EPA’s registration process also focuses on exposures for the general population, so it bases its calculations on how much residue consumers are likely to encounter on food, and how much farmers are likely to experience under normal conditions. Importantly, the EPA also requires that the company registering the pesticide — in this case, Monsanto — provides the studies used in the analysis. This requirement helps the EPA preserve its own budget, but it also introduces bias in the registration process since chemical companies are unlikely to bring studies showing negative impacts to the table.

Glyphosate as a Carcinogen

As glyphosate’s use worldwide exploded, public health advocates voiced skepticism about its safety, especially considering how much more of it we use now than we used to. This came to a head in 2015, when the International Agency for Research on Cancer (IARC) found that glyphosate-based herbicides are a “probable human carcinogen.” In making this declaration, the IARC used only publicly-available data (which excluded the industry-commissioned studies the EPA relied on) and considered a much wider range of exposures than the EPA. They also considered all the “inactive” ingredients in Roundup, rather than glyphosate alone, since these can alter how pesticide residues stick to food and behave in the body The EPA’s subsequent 2016 review, meanwhile, reiterated their position that glyphosate does not pose a cancer risk in humans.

The Glyphosate Safety Fight Rages On

Ultimately, the agencies addressed slightly different questions: The IARC answered “is it possible for any amount of glyphosate to cause cancer ?” while the EPA answered “Is it likely that a “normal” amount of glyphosate causes of cancer?” Both are valuable questions, but while the IARC concluded in a follow-up report that glyphosate is “unlikely to pose a carcinogenic risk to humans from exposure through the diet,” the EPA still hasn’t accounted for the possibility of real-life scenarios that fall outside of “normal exposures,” like spills or, as in the current court cases, people who used the chemical without protective gear because they believed it was harmless.

The EPA’s reliance on industry-funded research is concerning, and Monsanto, Bayer, and other agrichemical interests have deliberately muddied the science. Around the IARC press release, industry-backed scientists released reviews criticizing the research used in the IARC study, and continue to publish findings of non-toxicity in major, peer-reviewed journals. Meanwhile, a growing body of evidence suggests that even at government-tolerated exposure levels, glyphosate in food residues could present other health risks, from kidney damage to endocrine disruption. Concern among consumers about glyphosate safety is also on the rise, with a growing interest in a glyphosate residue-free certification.

Glyphosate Safety Debated in Court

The IARC designation and subsequent debate put Roundup in the spotlight as a potential carcinogen, and before long, Monsanto was facing a slew of lawsuits from cancer patients alleging that Roundup had caused their illness. Because cancer can be caused by natural mutation, environmental factors, and a host of chemicals and substances, it’s very difficult to prove in court that one chemical is to blame for a specific cancer case. This had prevented previous suits from moving forward. However, in 2018, a federal judge decided that the evidence on glyphosate was strong enough to proceed with the cases. The first victory came from a California school groundskeeper, Dewayne Johnson, who developed terminal non-Hodgkin lymphoma after working with Roundup. He was awarded $80 million in damages. A subsequent case found Monsanto responsible for the non-Hodgkin lymphoma diagnosis of a property owner who had used Roundup extensively to manage poison oak. In both cases, the verdict declared that not only was Monsanto liable for the cancer, but that they acted deliberately and maliciously to conceal the risk of cancer from consumers. A key piece of evidence was unsealed internal memos revealing that the company ghostwrote pro-glyphosate research and then handed it off to researchers to present as their own work, proving intention to mislead the scientific community and the public.

The Legal Path Forward

Bayer, the agrochemical giant that bought Monsanto in 2018, was successful in getting the payments in both cases reduced but hasn’t yet been able to reverse either judgment. In December, however, they took the case to the Court of Appeals with the support of the EPA, several state governments and industry groups.

Bayer’s current legal strategy rests on the disagreement between the EPA and other scientific bodies. They argue that labeling their products as potentially carcinogenic would be a violation of federal law since it contradicts the EPA’s own assessment of the product. Under this logic, they can’t be held liable for any of the cancer cases, since it would have been illegal for them to talk about cancer risk on the label. If the Court rules in their favor, this would mean the hundreds of cancer cases already in trial could be dismissed. Given the amount of money and interest involved in keeping glyphosate flowing, it’s unclear what the court will decide.

Regardless of the ruling, it seems that American farmers are still going to use glyphosate — most don’t have the time, equipment or capital to turn to organic methods. In the face of increasing weed resistance to glyphosate, agrochemical companies like Corteva are pitching new formulations intended to replace Roundup as a one-size-fits-all herbicide. Ultimately, this approach to weed management can only keep farmers stuck on the treadmill of buying new chemicals to combat new superweeds. This prompts a re-evaluation of the reason we need such aggressive herbicides in the first place: our current agricultural system demands miles of pristine corn and soy, and values this system above human and ecological health.