Cheerios is a staple in many households, but parents may want to think twice about pouring a bowl of those tasty oats as it may contain traces of a controversial weed-killer that has been linked to cancer, according to new research.
Independent testing commissioned by the Environmental Working Group, an environmental research and advocacy nonprofit, discovered elevated amounts of the herbicide glyphosate in 31 out of 45 oat-based breakfast foods analyzed.
Cheerios, Lucky Charms and Quaker Oats were among the products found to have glyphosate levels above the EWG’s health benchmark of 160 parts per billion — meaning it’s higher than what the group deems safe for children.
“There are levels above what we could consider safe in very popular breakfast foods,” toxicologist Alexis Temkin, author of the EWG report, told the New York Times.
The chemical glyphosate has been used as a pesticide for more than four decades and is the active ingredient in Monsanto’s Roundup weed killer. According to the U.S. Geological Survey, more than 200 million pounds of glyphosate are sprayed on crops each year. Farmers will spray the weed-killing chemical on crops, such as wheat, oats and lentils, before harvest.
Despite its commonplace use, glyphosate has been derided by health and environmental advocates as unsafe. Past research has claimed the herbicide causes cancer and the World Health Organization has labeled it a “probable carcinogen.”
Last week, a California jury ordered Monsanto to pay $289 million in damages to a school groundskeeper who developed non-Hodgkin’s lymphoma reportedly due to repeated glyphosate exposure.
But others have questioned the findings that glyphosate is cancer-causing. A 2017 Journal of the National Cancer Institute study found no association between the chemical and an increased cancer risk.
The U.S. Environmental Protection Agency has also determined that glyphosate is “not likely to be carcinogenic to humans.” In 1993, the EPA reclassified the chemical as a Group E carcinogen, which “signifies evidence of non-carcinogenicity in humans.”
“The EWG’s claim about cancer is false. Glyphosate does not cause cancer,” a spokesperson for Monsanto told Quartz in an email statement. “Glyphosate has a more than 40-year history of safe use. Over those four decades, researchers have conducted more than 800 scientific studies and reviews that prove glyphosate is safe for use.”
Monsanto said last week that it plans to appeal the decision in the California case.
At the time, the company’s vice president, Scott Partridge, said in a statement, “More than 800 scientific studies, the U.S. EPA, the National Institutes of Health and regulators around the world have concluded that glyphosate is safe for use and does not cause cancer.”
Both the Quaker Oats Company and General Mills, the maker of Cheerios, disagree with the EWG report’s results, defending their products as safe to consume. “We proudly stand by the safety and quality of our Quaker products,” Quaker Oats told Fortune in a statement. “Quaker does not add glyphosate during any part of the milling process. Glyphosate is commonly used by farmers across the industry who apply it pre-harvest.”
“Our products are safe and without question, they meet regulatory safety levels,” a spokesperson General Mills told the New York Times.
The Environmental Working Group said in a statement late Wednesday that it’s “deeply disappointed” by the companies’ “tone-deaf response” to its report.
“Simply stated, there is far too much glyphosate in their products for parents to feel comfortable feeding them to their kids,” the group continued in its statement. “It is especially disappointing because these two multi-billion dollar companies can take the simple step of telling their oat farmers to stop using glyphosate as a harvest-time desiccant on their crops.”
Although the potential health effects of glyphosate are hotly debated, the U.S. Food and Drug Administration has said it would consider the EWG’s findings.