Analysis: EPA Ignored Scientific Research Showing Monsanto’s Glyphosate Causes Cancer

WASHINGTON – A new analysis from the peer-reviewed scientific journal Environmental Sciences Europe documents the diametrically different approaches the U.S. Environmental Protection Agency and the World Health Organization took when determining the cancer risk from exposure to Monsanto’s weedkiller glyphosate.

The report shows that the EPA ignored a large number of peer-reviewed independent studies that link glyphosate to cancer in humans, instead using research paid for by Monsanto to support the agency’s position that glyphosate is not carcinogenic.

In contrast, in 2015, after reviewing extensive U.S., Canadian and Swedish epidemiological studies on glyphosate’s human health effects, as well as research on laboratory animals, WHO’s International Agency for Research on Cancer, or IARC, classified the chemical as “probably carcinogenic to humans.”

“IARC’s evaluation relied heavily on studies capable of shedding light on the distribution of real-world exposures and genotoxicity risk in exposed human populations, while EPA’s evaluation placed little or no weight on such evidence,” wrote Charles Benbrook, Ph.D., the author of the new study.

As the new study details, the EPA relied largely on studies paid for by Monsanto and other agrochemical companies, ignoring the large and growing body of independent research connecting the chemical with genotoxicity.

Genotoxicity is the damaging effect a chemical can have on DNA, triggering mutations that can lead to cancer. IARC scientists reviewed 118 different assays and found strong evidence that glyphosate may cause genotoxicity.

The EPA’s assessment included fewer than half of these studies, allowing the agency to express its position that glyphosate is “not likely carcinogenic.”

Since the IARC assessment, an additional 26 of 27 published studies have reported evidence that glyphosate can be genotoxic. In 2017, glyphosate was listed by California’s Office of Environmental Health Hazard Assessment as a chemical known to the state to cause cancer.

“The fact that the EPA relied largely on Monsanto’s own research to reach the conclusion glyphosate doesn’t cause cancer could be turned into a skit on The Daily Show,” said Olga Naidenko, Ph.D., senior science advisor for children’s environmental health at EWG. “Allowing a company like Monsanto, with a long and damaging history of deception, to influence the EPA’s assessment of its own product is outrageous.”

Glyphosate, marketed by Monsanto as Roundup, is one of the most widely used herbicides in the U.S. and worldwide. The German crop chemical and drug company Bayer bought Monsanto last year and has since dropped the former company’s name from the product.  

Last year, EWG commissioned two rounds of testing for the presence of glyphosate in popular oat-based cereal and other oat-based foods marketed to children. Of the 73 conventional product samples that EWG tested, all but two contained the weedkiller.

More than 225,000 people have signed a petition from EWG and Just Label It calling on General Mills, Quaker and Kellogg’s to get glyphosate out of their products. EWG and a number of food and nutrition companies have petitioned the EPA to sharply limit glyphosate residues allowed on oats and prohibit its use as a pre-harvest drying agent. Companies signing the petition include MegaFood, Ben & Jerry’s, Stonyfield Farm, MOM’s Organic Market, Nature’s Path, One Degree Organic Foods, Happy Family Organics, Patagonia, PCC Community Markets and Amy’s Kitchen.


The Environmental Working Group is a nonprofit, non-partisan organization that empowers people to live healthier lives in a healthier environment. Through research, advocacy and unique education tools, EWG drives consumer choice and civic action.

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