In recent years, Monsanto and parent company Bayer have faced thousands of lawsuits from people who claim that they developed cancer from using the popular weedkiller Roundup. Indeed, Roundup is the most popular herbicide in the world, so speculations about its possible risks may concern many consumers.

However, there is some debate about whether or not Roundup does lead to cancer — some organizations say that Roundup’s main ingredient, glyphosate, does cause cancer, while others consider it to be safe.

What Is Glyphosate, and Is It Safe?

The main ingredient in Roundup is a weed killer called glyphosate. Organizations around the world are not in total agreement about whether or not the chemical can cause cancer.

In 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) determined that glyphosate is “probably carcinogenic to humans.”

However, the U.S. Environmental Protection Agency takes a different stance, determining that glyphosate exposure does not put patients at risk for cancer. Canadian health authorities and the European Food Safety Authority similarly state that it is unlikely that glyphosate causes cancer.

Additionally, Ecojustice and other critics claim that some national health organizations made their decisions that glyphosate was safe based on biased studies from Monsanto and Bayer.

The difference in opinion has sparked an analysis by the Environmental Sciences Europe journal. The paper aimed to look into why the EPA and the IARC have come to opposing conclusions regarding the safety of glyphosate.

After looking at the analysis done by each organization, the paper found that the EPA relied on “unpublished regulatory studies” – many of which were funded by the industry. In contrast, the evidence looked at by the IARC was sourced from “mostly peer-reviewed studies.”

According to the study, authored by Charles Benbrook, an agricultural economist, 99 percent of the studies considered by the EPA found that the chemical did not cause cancer while 70 percent of studies reviewed by the World Health Organization came to the opposite conclusion.

“It’s kind of easy to understand why EPA would say, ‘Well, geez, you know, it must be okay,'” Benbrook told Business Insider. “It was okay because they were looking at a bunch of negative studies that Monsanto [did]. Monsanto repeated essentially the same study like 30 times.”

Monsanto has rejected this analysis. Instead, the company says that hundreds of studies on glyphosate in the EPA’s database were not funded by Monsanto – meaning that their bias did not sway the regulator.

Does Bayer Claim People Cannot Develop Cancer from Using Roundup?

CBS notes that Bayer acquired Monsanto in 2018 after Monsanto had already become well known for producing Roundup. With the acquisition of Monsanto, Bayer acquired the legal problems that came along with the popular pesticide.

Despite legal criticism, Bayer maintains that glyphosate and Roundup are both safe. However, critics worry that this is a biased position. Canadian law charity Ecojustice claimed that Monsanto and Bayer are aware that glyphosate causes cancer, and actively covered up this fact. Ecojustice points to a United States lawsuit that reportedly brought to light the “Monsanto Papers,” internal documents from the company that suggested that the company altered scientific studies to make it seem as if glyphosate was safe.

“At the end of the day, whether you’re in the court of law, regulatory agencies, or court of public opinion, it’s the science that should matter here,” Bayer said in an email statement to Business Insider.

“And the extensive body of science over 40 years, including several recent human epidemiology studies, shows that glyphosate-based herbicides are not associated with NHL. Customers who know these products best continue to rely on them.”

However, consumers argue that the thousands of lawsuits against Bayer speak for themselves regarding Roundup’s alleged cancer risk.

What Kind of Cancer Does Roundup Cause?

Reportedly, there is increasing evidence that long-term exposure to glyphosate can have negative health effects. Business Insider explains that many patients who filed Roundup lawsuits claimed that they developed non-Hodgkin’s lymphoma as a result.

One couple who made such claims were awarded a $2 billion verdict last year from a California jury.

According to Business Insider, some studies have outlined the connection between Roundup and non-Hodgkin’s lymphoma. 

A recent study from the University of Washington, published in the journal Mutation Research in February 2019, concluded that exposure to glyphosate increases a person’s risk of developing non-Hodgkin’s lymphoma by a whopping 41 percent.

“All of the meta-analyses conducted to date, including our own, consistently report the same key finding: exposure to GBHs (glyphosate-based herbicides) are associated with an increased risk of NHL,” the authors wrote in the study, according to CNN.

Roundup has been linked with other types of cancer as well, including B-cell lymphoma, T-cell lymphoma, chronic lymphocytic leukemia (CLL), and hairy cell leukemia.

However, Monsanto often says that a 2017 study indicated that there is no “statistically significant” association between glyphosate and cancer of any kind, despite significant patient concern that people may develop cancer from using Roundup. Business Insider does counter this by noting that the same study determined that people who spray glyphosate as a pesticide may be more likely than the general population of developing acute myeloid leukemia.