Glyphosate has also made headlines for its suspected link to a type of cancer called non-Hodgkin’s lymphoma (NHL). The link has been contested in court and continues to be tested by scientists. In 2015, the World Health Organization (WHO) said the chemical was “probably carcinogenic to humans” based on animal studies, the best evidence at the time. But the EPA maintains that glyphosate is “unlikely to be carcinogenic to humans” based on several studies, including a large 2017 study of agricultural workers published in the Journal of the National Cancer Institute that found no link between glyphosate and cancer.
A 2019 review by independent researchers, published in the journal Mutation Research/Mutation Research Reviews, reviewed data from several studies on the potential carcinogenic effects of glyphosate, including a large sample of farm workers in the United States. The review found that workers with the highest exposure to glyphosate had a 41 percent increased risk of NHL.
“I believe [this number] is still an underestimate,” said lead author Luoping Zhang, a toxicologist at the University of California, Berkeley. The data the researchers analyzed was collected in 2010, but glyphosate use has increased since then, Zhang said. In addition, many years can pass between a person’s exposure to the chemical and causing cancer, she said.
Other studies on the health effects of glyphosate exposure back up what Zhang and her colleagues found in their 2019 review. Another study published in the International Journal of Epidemiology in 2019, for example, pooled data on glyphosate exposure and farm worker health from the United States, France, and Norway, and also found that exposure to the chemical was associated with certain types of NHL.
Despite this, there is still little research on the topic. Scientists need to conduct more studies with human subjects and get similar results before they can definitively link glyphosate to NHL or any other cancer.
Key questions remain unanswered. For example, scientists do not yet understand exactly how the chemical triggers cancer development. And they don’t know how much exposure to the chemical is needed to pose a risk.
According to the World Health Organization, glyphosate levels entering food are unlikely to be high enough to cause cancer. Most at risk are farm workers, who may inhale chemicals when spraying them and absorb relatively large amounts through their skin and eyes, Zhang said. Zhang added that some researchers suspect that other diseases may also be linked to glyphosate exposure, such as celiac disease, but there is little evidence to support this.