Exposure to glyphosate, a common broad-spectrum herbicide used worldwide, increases the risk of non-Hodgkin’s lymphoma (NHL) by 41 percent in humans, a study says.
Over the last few years, there has been controversy over the carcinogenic risks of glyphosate among regional, national and international health care agencies. In 2015, the World Health Organization‘s (WHO) International Agency for Research on Cancer (IARC) stated that glyphosate is “probably carcinogenic to humans.”
In the same year, Bayer went even further and claimed the herbicide was “a safe and efficient weed control tool.” As a result, Bayer and Monsanto, an agricultural company acquired by Bayer, were sued by people worldwide over claims that Monsanto’s Roundup agricultural herbicides containing glyophosate were responsible for NHL.
Now, a team of researchers from the University of California-Berkeley and their collaborators carried out a meta-analysis to investigate the relationship between glyphosate exposure and NHL risk in human populations.
The meta-analysis included the 2018 update of the Agricultural Health Study (AHS) cohort, as well as five case-control studies, involving nearly 65,000 participants who had been exposed to the herbicide. The AHS is a prospective study designed to evaluate cancer incidence and other medical conditions in a group of licensed pesticide applicators and their spouses residing in Iowa and North Carolina.
Meta-analysis results revealed a compelling link between glyphosate exposure and higher risk for NHL in human populations. These findings were also supported by animal studies showing that mice treated with pure glyphosate had a higher incidence of malignant lymphoma.
“All of the meta-analyses conducted to date, including our own, consistently report the same key finding: exposure to [glyphosate-based herbicides] are associated with an increased risk of NHL,” Rachel Shaffer, co-author of the meta-analysis, said in a news release.
“However, given the heterogeneity between the studies included, the numerical risk estimates should be interpreted with caution. Additionally, … the available studies [may] not capture the possible effects of increased population exposures due to secular increases in use where “green burn-down” practices introduced in the mid-2000s may be a particularly important source of population exposures,” the researchers stated.
Bayer maintained the same stance, arguing that the meta-analysis results were obtained by “statistical manipulation” and there were “flaws” in the study design and methods. The company finished by saying that the study “provides no scientifically valid evidence that contradicts the conclusions of the extensive body of science demonstrating that glyphosate-based herbicides are not carcinogenic.”
Following Bayer’s claims, the authors of the study assured that the relationship they found between glyphosate exposure and NHL risk is real, reinforcing the carcinogenic potential of the herbicide.