Glyphosate Cancer Link Claims by Politicians Lack Definitive Scientific Evidence

Glyphosate Cancer Claims Remain Scientifically Contested Despite Political Debates

Following an executive order from the Trump administration promoting glyphosate production, a heated debate has reignited over whether the widely used herbicide causes cancer. Democratic lawmakers have made pointed claims about cancer risks, while regulatory agencies worldwide maintain the chemical is unlikely to pose carcinogenic threats under normal exposure.

President Donald Trump’s February 18 executive order designated glyphosate production as necessary for national security, drawing criticism from those who consider the chemical dangerous. Glyphosate, first marketed by Monsanto in 1974 as Roundup, is now manufactured in the U.S. exclusively by Bayer, which acquired Monsanto in 2018.

Health and Human Services Secretary Robert F. Kennedy Jr., who has previously claimed glyphosate causes cancer, defended the executive order despite his long-standing opposition to the herbicide. This apparent contradiction prompted swift reactions from Democratic lawmakers.

“This executive order is a slap in the face to the thousands of Americans who have gotten cancer from glyphosate,” said Senator Cory Booker (D-NJ) in a February 19 statement. During a confirmation hearing for the surgeon general nominee, Senator Ed Markey (D-MA) accused Trump of “siding with the chemical manufacturing company that is, in fact, causing the cancers.”

Some Republicans have also expressed concern, though with more measured language. Representative Nancy Mace (R-SC) stated that glyphosate “has been linked” to cancer, writing on social media: “Glyphosate and other pesticides don’t belong on our food or in our children’s bodies. We are systematically poisoning ourselves.”

The scientific evidence, however, presents a more complex picture than political rhetoric suggests. While some studies have identified associations between glyphosate exposure and cancer in humans or laboratory animals, findings have been inconsistent, leading scientists to different conclusions about the overall evidence.

A large National Institutes of Health study published in 2017 did not find an association between glyphosate and non-Hodgkin lymphoma (NHL) or other cancers in agricultural workers. This finding stands in contrast to the World Health Organization’s International Agency for Research on Cancer (IARC), which in 2015 classified glyphosate as “probably carcinogenic to humans” based on limited real-world evidence and laboratory animal data.

“The overall picture with glyphosate is messy,” explained David Eastmond, professor emeritus at the University of California, Riverside, who studies chemical carcinogenesis. “The human studies are messy, the animal studies are messy, the mechanistic studies are messy. And so within that messiness, you try and draw conclusions, and different people interpret that in different ways.”

Glyphosate-based herbicides are the most commonly used weedkillers globally. Centers for Disease Control and Prevention monitoring has detected glyphosate in most people’s urine, though the agency notes this alone “does not mean that glyphosate causes disease or adverse effects.” The chemical does not accumulate in the body and is rapidly eliminated.

Agricultural workers face the highest exposure levels, while the general public may encounter trace amounts in foods, particularly grains and legumes. Bayer began phasing out residential glyphosate products in 2023, citing litigation risk reduction.

The company has proposed a $7.25 billion settlement for current and future lawsuits alleging harm from Roundup. Meanwhile, the Supreme Court will soon hear arguments on whether people can sue Bayer under state law for failure to warn about potential harms on product labels.

Differences in scientific conclusions partly stem from varying assessment methods. IARC evaluated whether glyphosate theoretically could cause harm (hazard assessment), while regulatory agencies typically assess how likely harm is under realistic exposure conditions (risk assessment).

The Agricultural Health Study, a prospective cohort study following more than 54,000 licensed pesticide applicators over many years, found no association between glyphosate use and any cancer type. This stands in contrast to case-control studies that have shown some associations with NHL.

A 2019 meta-analysis found that groups reporting the highest level of glyphosate-based herbicide exposure had a 41% higher rate of NHL than non-users. However, a 2020 EPA review questioned the rationale for focusing on highest-exposure groups and emphasized that the Agricultural Health Study found no increasing risk of NHL with higher glyphosate exposure.

The EPA is scheduled to issue a revised decision on glyphosate by October. “This year, EPA will undertake a comprehensive, transparent, and rigorous scientific review of glyphosate to evaluate its use and ensure decisions are fully aligned with the best available science as well as human health and environmental protections,” an agency spokesperson stated.

As the debate continues, scientists on both sides acknowledge the complexity of the evidence. For the average consumer exposed to trace amounts in food, most researchers suggest the cancer risk, if any, is likely minimal. However, agricultural workers with high exposures face more uncertainty, driving continued research into this widely used herbicide.