New scientific analysis of the carcinogenic potential of glyphosate herbicides, the most widely used herbicides in the world, revealed that people highly exposed to popular pesticides are 41% more likely to develop a type of cancer called non-Hodgkin's lymphoma .

Evidence "corroborates a convincing link" between glyphosate herbicide exposures and increased risk of non-Hodgkin's lymphoma (NHL), the authors concluded, although they said that numerical risk estimates should be interpreted with caution.

The findings of five US scientists contradict US Environmental Protection Agency (EPA) safety assurances and are presented as regulators in several countries that are considering limiting the use of glyphosate products in agriculture.

Monsanto and its German owner Bayer AG face more than 9,000 lawsuits in the United States by people with NHL who attribute their diseases to Monsanto's glyphosate herbicides. The first complainant to stand trial won a unanimous jury verdict against Monsanto in August, a verdict that the company is appealing. The next trial, involving a separate plaintiff, is expected to open on February 25, and several other lawsuits are scheduled for this year and until the year 2020.

Monsanto states that no legitimate scientific research has demonstrated definitive association between glyphosate and NHL nor any type of cancer. Company officials said hundreds of studies have concluded that glyphosate is "unlikely" to cause cancer.

The company claims that scientists at the International Agency for Research on Cancer (IARC) who classified glyphosate as a probable human carcinogen in 2015 behaved inappropriately and did not give enough weight to several important studies.

Activists protest against the merger of Bayer and Monsanto in Bonn, Germany, in 2018.

Activists protest against the merger of Bayer and Monsanto in Bonn, Germany, in 2018. Photo: Wolfgang Rattay / Reuters

But the new analysis could potentially complicate Monsanto's defense of its best-selling herbicide. EPA has engaged three of the authors of the study as members of the board of directors of a 2016 glyphosate scientific advisory group. The new article was published by Mutation Research / Reviews in Mutation Research , whose editor in chief is the EPA scientist David DeMarini.

The authors of the study say that their meta-analysis is different from previous evaluations. "This article shows more clearly than previous meta-analyzes that there was evidence of an increased risk of NHL due to glyphosate exposure," said Lianne Sheppard, co-author, professor at the Department of Environmental Health Sciences and at the University of Washington. . "From the point of view of the health of the population, there are real concerns."

Sheppard was one of the EPA's scientific advisors on glyphosate and was part of a group of advisers who told the EPA that she had not followed the appropriate scientific protocols to determine that glyphosate was not likely to cause cancer. "It was wrong," Sheppard said of the Glyphosate's assessment by the EPA. "It was pretty obvious that they did not follow their own rules. "Is there any evidence that it is carcinogenic? The answer is yes."

An EPA spokesman said: "We are reviewing the study." Bayer, who bought Monsanto in the summer of 2018, has not responded to a request for comment about the study.

A Bayer statement on glyphosate cites the EPA's assessment and states that glyphosate herbicides have been "widely evaluated" and have proven to be a "safe and effective weed control tool." ".

The study authors stated that their new meta-analysis evaluated all published human studies, including a government-sponsored, 2018 updated study, known as the Agricultural Health Study (1998). Agricultural Health Study – AHS). Monsanto said that the updated AHS study showed that there was no connection between glyphosate and NHL. In the new meta-analysis, the researchers indicated that they focused on the most exposed group in each study, as they would be more likely to be at high risk if glyphosate herbicides were to be used. 39, origin of NHL.

By examining only individuals with a high exposure to the pesticide in the real world, it is less likely that confounders will skew the results, said the authors. In essence, if there is no real link between the chemical and cancer, even highly exposed people should not develop cancer at a significant rate.

In addition to reviewing the studies in humans, the researchers also examined other types of studies on glyphosate, including many animal studies.

"Together, all meta-analyzes conducted to date, including our own, consistently report the same key finding: GBH exposure is associated with an increased risk of NHL," the scientists concluded.

David Savitz, professor of epidemiology at the Faculty of Public Health at Brown University, said the work was "well conducted" but lacked "fundamentally new information".

"I would say that this confirms the concern and the need for an assessment, but that the issue is not resolved definitively," Savitz said.

Carey Gillam is a journalist and author, and researcher in the public interest of the American research group Right to Know, a nonprofit research group in the food sector.