The short answer is: the scientific evidence is genuinely contested, and regulatory agencies disagree on whether glyphosate causes cancer. In 2015, the International Agency for Research on Cancer (IARC), a division of the World Health Organization, classified glyphosate as “probably carcinogenic to humans” based on limited evidence in humans and sufficient evidence in animal studies. However, the U.S. Environmental Protection Agency (EPA) and many other regulatory bodies, including the European Commission and Japan’s pesticide authority, concluded that glyphosate is not likely to be carcinogenic at the exposure levels people typically experience.
The disagreement reflects different approaches to evaluating the available research, different standards of proof, and different risk assessment methodologies—not a simple “yes” or “no” answer. The most visible consequence of this scientific dispute has been litigation. Thousands of farmers, agricultural workers, and homeowners have filed lawsuits claiming that exposure to glyphosate-based herbicides like Roundup caused them to develop non-Hodgkin’s lymphoma, a type of blood cancer. Monsanto, the original developer of Roundup (now owned by Bayer), settled multiple lawsuits for billions of dollars. These settlements, however, were made without Monsanto or Bayer admitting wrongdoing—a fact that has confused many people into thinking the settlements prove glyphosate causes cancer, when in reality they reflect the company’s calculation that settling was cheaper than continuing costly litigation.
Table of Contents
- What Exactly Is Glyphosate and Where Is It Found?
- The IARC Classification and What It Actually Means
- Non-Hodgkin’s Lymphoma and the Agricultural Workers’ Story
- How Different Countries Evaluate the Same Evidence Differently
- The Role of Biomonitoring and Individual Exposure Levels
- What the Litigation Settlements Actually Settled
- What Individuals Should Do About Glyphosate Exposure Today
What Exactly Is Glyphosate and Where Is It Found?
Glyphosate is a broad-spectrum herbicide—a chemical that kills most plants by interfering with an enzyme necessary for plant survival. It was first synthesized in 1950 and commercialized by Monsanto in 1974 under the brand name Roundup. The herbicide became ubiquitous after Monsanto developed genetically modified crops (primarily soybeans and corn) that could tolerate glyphosate, allowing farmers to spray it to kill weeds without killing their crops.
Today, glyphosate is used on millions of acres of farmland worldwide, in forestry and land management, and by homeowners in products for lawn and garden use. Outside agricultural settings, glyphosate residues have been detected in drinking water, groundwater, soil, and food crops—particularly in wheat, oats, chickpeas, and lentils. A key limitation when assessing glyphosate safety is distinguishing between exposure levels: a farmworker who handles and sprays the chemical directly faces vastly different exposure than someone who consumes food with trace residues of the herbicide. This distinction is central to the disagreement between regulatory bodies, which set “safe” exposure limits based on assumptions about how much a typical person is exposed to.
The IARC Classification and What It Actually Means
In March 2015, IARC’s Working Group classified glyphosate in Group 2A—”probably carcinogenic to humans.” This classification was based on three studies showing increased risk of non-Hodgkin’s lymphoma in people occupationally exposed to glyphosate, limited human evidence overall, and evidence from animal studies in mice and rats. IARC’s classification system is hazard-based: it asks “is there any credible evidence this substance can cause cancer?” rather than “is this substance likely to cause cancer at typical exposure levels?” Because of this approach, IARC tends to classify substances more conservatively than other regulatory bodies. The EPA and European Food Safety Authority (EFSA) reached different conclusions using different methodologies.
The EPA concluded in 2020 that glyphosate is “not likely to be carcinogenic to humans” at expected exposure levels, citing a larger body of epidemiological studies, some of which found no increased cancer risk, and arguing that the animal study evidence was insufficient to prove causation in humans. The EFSA similarly assessed the evidence as insufficient to classify glyphosate as carcinogenic. A critical limitation in interpreting these disagreements: the studies that form the basis of these assessments sometimes conflict with each other, have different sample sizes, different exposure measurements, and different statistical power—making it possible for two equally competent groups to draw different conclusions from the same underlying evidence.
Non-Hodgkin’s Lymphoma and the Agricultural Workers’ Story
Non-Hodgkin’s lymphoma (NHL) is a cancer of the immune system, and it is the cancer type most frequently cited in glyphosate litigation. Several studies of agricultural workers, particularly in the United States, have reported associations between glyphosate exposure and increased NHL risk. The most commonly cited study, published in 2018 in Mutation Research, found that occupational exposure to glyphosate was associated with a 41% increased risk of NHL.
However, other large studies, including cohort studies of pesticide applicators and agricultural workers in Canada and the United States, found no statistically significant association between glyphosate and NHL risk. The comparison between occupational and consumer exposure is important here: agricultural workers who mix, load, and spray glyphosate—especially those without consistent personal protective equipment—likely receive substantially higher doses than the general public. This distinction matters because establishing that a chemical can cause harm at very high exposures says nothing definitive about whether it causes harm at lower exposures. A specific warning: if you are occupationally exposed to glyphosate, understanding your actual exposure level (through biological monitoring, work practices, or environmental sampling) is more relevant to your individual risk than the existence of studies showing associations at occupational doses.
How Different Countries Evaluate the Same Evidence Differently
The disagreement between IARC and regulatory agencies like the EPA is not primarily about the facts—they are reviewing largely the same studies—but about how to interpret uncertain evidence and what level of evidence is required before restricting a widely used chemical. The EPA’s risk assessment includes the assumption that exposure can be controlled through label instructions and that the typical American consumer’s exposure through food is negligible. The EFSA’s European risk assessment reached similar conclusions but set acceptable daily intake levels somewhat lower than the EPA. By contrast, several countries have taken more precautionary stances.
The state of California listed glyphosate as a known carcinogen under Proposition 65 in 2017, based partly on IARC’s classification. Vietnam banned glyphosate in 2022 citing health concerns. France and the European Union both renewed glyphosate approval but with ongoing review and restrictions on use. This divergence reflects different regulatory philosophies: the EPA historically requires stronger evidence of harm before restricting chemicals, while European agencies more often invoke a “precautionary principle” that assumes some restrictions are warranted when evidence is suggestive but not conclusive.
The Role of Biomonitoring and Individual Exposure Levels
Exposure assessment is central to understanding glyphosate’s actual health risk, yet it remains imprecise. Glyphosate can be measured in urine, blood, and other biological samples, but the clinical significance of finding glyphosate in a person’s body is unclear. Studies have detected glyphosate in the urine of agricultural workers, gardeners, and—in some studies—the general population. However, measuring the presence of a chemical is different from measuring the dose or duration of exposure that might cause harm.
A warning: many of the studies showing glyphosate in the general population’s urine are small or use inconsistent measurement methods, making it difficult to determine whether exposures are increasing, stable, or declining, or whether they differ meaningfully between groups. Occupational exposure during spraying or mixing is typically far higher than exposure through residues in food and water. A farmworker mixing concentrated herbicide in a tank and applying it over hours receives a dose measured in milligrams per kilogram of body weight; a consumer eating food with trace herbicide residues receives a dose measured in micrograms or less. This difference of 1,000-fold or more is not semantics—it affects whether the body’s detoxification systems can process the chemical or whether it accumulates to potentially harmful levels.
What the Litigation Settlements Actually Settled
Between 2018 and 2024, Bayer (which acquired Monsanto in 2018) settled thousands of lawsuits for a total exceeding $10 billion. The three largest settlements involved approximately 125,000 plaintiffs in the United States. Importantly, none of these settlements included an admission of liability or wrongdoing by Bayer.
In legal terms, a settlement is a business decision—in Bayer’s case, the company determined that paying the settlements was less costly than defending against thousands of individual trials, defending against potential punitive damages, and ongoing litigation. Settlements are not evidence that the defendant’s product caused the harm alleged; they are evidence that the defendant preferred paying over continued litigation. The terms of some settlements included provisions allowing plaintiffs to pursue additional medical monitoring or access to claims processes if they later developed cancer, but again, these provisions reflect litigation risk management, not scientific acknowledgment of causation. For people trying to understand whether glyphosate caused their own cancer, the settlements provide no answer—they are agreements between parties about money and liability allocation, not scientific determinations.
What Individuals Should Do About Glyphosate Exposure Today
If you are an agricultural worker or regularly use glyphosate-based products, the evidence suggests that minimizing your exposure through protective equipment (gloves, eye protection, long sleeves), proper ventilation during mixing and application, and following label instructions is a reasonable precaution. If you are concerned about residues in food, choosing foods grown without synthetic pesticides—either through certified organic farming or through farmers who use alternative weed control methods—is an option, though the evidence that current residue levels in conventionally grown food cause cancer is not strong enough to be considered a high-priority health concern compared to other factors like diet quality and physical activity.
For individuals who have been diagnosed with non-Hodgkin’s lymphoma and had occupational exposure to glyphosate, consulting with a physician or occupational medicine specialist about whether your exposure history is consistent with an occupational contribution to your disease is worthwhile. A consultation with an attorney who specializes in product liability may also help you understand whether your specific circumstances might support a legal claim, though the current state of the science means that such claims carry substantial uncertainty about proving causation. The regulatory debates and litigation will likely continue as new studies emerge and as more countries reassess the evidence over coming years.