If you or your children are eating Cheerios right now, there’s a good chance that they’re accompanied by a potentially harmful weed killer called Roundup.
The Environmental Working Group, a Washington, D.C. advocacy group that assesses chemicals in consumer products, on Wednesday released the results of a test it conducted on popular oat-based products, like Cheerios, Lucky Charms, Kind Bars, Nature Valley bars, and others, to determine whether they contained any of the herbicide glyphosate. Glyphosate is the active ingredient in Monsanto’s Roundup weed killer, and at high levels, has been linked to cancer.
Unfortunately, some of the results were not what you might hope.
In its testing, the EWG tested 45 samples of conventionally grown oats and 16 of organically grown oats. In 43 of the 45 conventional cases, it detected glyphosate. And in 31 of those cases, glyphosate levels were above the organization’s health benchmark of 160 parts per billion. On the organic side, just five products were discovered to have had Glyphosate and none of them reached the 160ppb benchmark.
The benchmark is designed to provide a framework for how much glyphosate humans can ingest daily without having potentially negative health effects. The higher the level, the worse for your health.
The most concerning findings came with Quaker Old Fashioned Oats, which had levels higher than 1,000ppb. Three Cheerios samples had levels ranging from 470ppb to 530ppb. Lucky Charms were tested in two samples and found to have 400ppb and 230ppb levels, respectively.
“We proudly stand by the safety and quality of our Quaker products,” the company replied 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.” It added that the reported levels of the chemical “are significantly below any regulatory limits” and compliance standards for human consumption.
Kind Vanilla, Blueberry Clusters with Flax Seeds had levels of 50ppb and 60ppb in the testing, below the 160ppb benchmark. The company’s Kind Oats & Honey with Toasted Coconut Bar reported no glyphosate in the first test, but 120ppb in the second.
Nature Valley’s Granola Protein Oats ‘n Honey had 220ppb and 170ppb in its two tests, respectively. The company’s Cunchy Granola Bars, Oats ‘n Honey had 340ppb and 120ppb in its two tests.
Some organic options proved to be the healthiest. Simple Truth Organic Instant Oatmeal, for instance, didn’t have the chemical in its oats. The same was true for Kashi’s Heart to Heart Organic Honey Toasted cereal. And if you’re looking for a healthy granola bar that doesn’t contain glyphosate, according to EWG, opt for the Cascadian Farm Organic Harvest Berry.
Glyphosate has long been a major concern for health advocates. Both the World Health Organization and California state scientists have found links between the herbicide and cancer.
Monsanto’s Roundup, meanwhile, is the most heavily used pesticide in the U.S. It’s estimated that 250 million pounds of Roundup are sprayed on American crops to keep weeds down and crops living. But since it’s often sprayed before harvest, it clings to the crops, leaving them in food.
According to EWG, glyphosate is an especially concerning problem for children. The U.S. Environmental Protection Agency, for instance, has found that children between the ages of one and two have much higher exposure than older people. Their daily glyphosate intake is estimated at 230 times the 160ppb benchmark, according to EWG.
Monsanto did not immediately respond to a Fortune request for comment on the findings.
Editor’s Note, Aug. 15, 2018: This article has been updated to include comment from the Quaker Oats Co.