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Does glyphosate cause cancer?

Lewis Sanders IV
July 11, 2018

A California man is dying of cancer, and he is blaming the glyphosate found in Monsanto's Roundup, while a judge has allowed hundreds of more cases to move forward. But research shows the link is anything but clear.

A tractor on a field
Image: picture-alliance/All Canada Photos/C. Cheadle

A San Francisco court began hearing opening statements in the first US trial of its kind on Monday: A California man dying of cancer is suing agrochemical giant Monsanto, claiming the popular weed-killer Roundup is to blame for the disease.

Days after, a federal judge in San Francisco allowed hundreds of lawsuits against Monsanto to go forward. The judge said on Wednesday that there was sufficient evidence for a jury to hear the case.

The plaintiffs argue that Monsanto products containing glyphosate, most notably Roundup, were at fault for cancer that either they or their deceased relatives were diagnosed with.

In particular, the trial of 46-year-old Dewayne Johnson was expedited due to his likely death in the coming months from non-Hodgkin lymphoma, according to his lawyer.

What happened?

Johnson, who worked as a groundskeeper at a school near San Francisco for two years, argues that Monsanto's Roundup herbicide caused his cancer and that the company failed to warn against the product's fatal effects, according to court documents.

Johnson sprayed Roundup on school grounds "20 to 40 times per year, sometimes hundreds of gallons at a time," his lawyer told AFP news agency.

Two years after starting his job in 2012, Johnson was diagnosed with cancer. He filed the lawsuit against Monsanto two years later after being unable to work due to the disease.

Johnson has "suffered severe and permanent physical and emotional injuries" and "endured economic loss (including significant expenses for medical care and treatment) and will continue to incur these expenses in the future," according to the lawsuit.

Read more: Glyphosate: The key points in an endless debate

Does glyphosate cause cancer?

While critics are quick to describe glyphosate — the main chemical substance in Roundup — as carcinogenic, research is far from definitive on the question. Here's what international bodies, environmental authorities and researchers have to say:

  • The EU's European Food Safety Authority said in 2015: "EU peer review experts, with only one exception, concluded that glyphosate is unlikely to pose a carcinogenic hazard to humans and the evidence does not support classification with regard to its carcinogenic potential."
  • The WHO's International Agency for Cancer Research in 2015 classified glyphosate as "probably carcinogenic to humans." At the same time, it said that, "For the herbicide glyphosate, there was limited evidence of carcinogenicity in humans for non-Hodgkin lymphoma. The evidence in humans is from studies of exposures, mostly agricultural, in the USA, Canada and Sweden published since 2001."
  • The US Environmental Protection Agency (EPA) in 1985 labeled glyphosate a "possible human carcinogen," but that classification was rescinded in 1991 by an internal committee, saying there wasn't enough evidence to claim that it was carcinogenic. It was consequently labeled a chemical with "evidence of non-carcinogenicity for humans." A new review process launched in 2015 said data "at this time do no (sic) support a carcinogenic process for glyphosate."
A protester holds up a placard that says: "Monsanto: We poison everything you eat"
Critics have taken to streets across Europe to protest the use of herbicides with glyphosateImage: picture-alliance/AP Photo/F. Mori

What does Monsanto say?

Monsanto, which was acquired last month by German pharmaceutical company Bayer, has defended its product, claiming it does not pose a threat to humans.

"Comprehensive toxicological and environmental fate studies conducted over the last 40 years have time and again demonstrated the strong safety profile of this widely used herbicide," Monsanto said in its 2016 report on the chemical substance.

"Glyphosate exhibits low toxicity to humans and non-plant wildlife over both short- and long-term exposures. It is does (sic) not cause cancer and it is not an endocrine disruptor."

Monsanto's controversial past

This is not the first time Monsanto's products have allegedly caused harm to human health. The century-old agrochemical company once manufactured a defoliant called "Agent Orange," which was used during the US war against Vietnam.

The US Department of Veterans Affairs has "recognized certain cancers and other health problems as presumptive diseases associated with exposure to Agent Orange … during military service."

Monsanto also manufactured the insecticide DDT from 1944 to 1957, which the US has "classified as a probable human carcinogen."

Read more: Farming without glyphosate: How would that work?

Glyphosat container shows the active ingredient
Glyphosate is the primary chemical substance in Monsanto's Roundup herbicideImage: picture-alliance/dpa/P. Pleul

What's the situation in Germany?

The use of glyphosate is allowed in Germany. However, Environment Minister Svenja Schulze of the Social Democrats said in March that she will pursue ending the use of glyphosate in the country as soon as possible.

Some stores in Germany have pulled products with glyphosate.

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