Sorry, kids (and kids-at-heart)—it's 2018, and even Cheerios are tainted. According to a study conducted by the Environmental Working Group released this morning, there’s a very good chance your morning cereal has traces of the potentially cancer-causing chemical glyphosate, better known as the active ingredient in the weed killer Roundup.

According to EWG, of 61 samples of popular grain-based products like cereals, oatmeals, and granola bars—including Cheerios Toasted Whole Grain Cereal, Lucky Charms, Nature Valley Oats ‘n’ Honey granola bars, and Quaker Old Fashioned Oats—48 contained traces of the herbicide, and half of the samples contained levels considered unsafe for children.

Based on nutrition guidelines and toxicity standards, EWG determined that 160 parts per million of glyphosate in a daily serving of the food products could constitute a cancer risk. Quaker Dinosaur Eggs instant oatmeal contained between 620 and 780 ppm. Lucky Charms had between 230 and 400 ppm. One sample of Quaker Old Fashioned Oats tested positive for a whopping 1,100 ppm.

Hundreds of millions of pounds of glyphosate, as EWG explains, are used on commodity crops like corn and soybeans every year as an herbicide. An increasingly common practice for many cereal farmers—the ones growing wheat, oats, and barley—is to spray glyphosate on their grain crop prior to harvesting to speed up the drying process. Grains, unlike other produce, are not harvested when they’re green; the plants have to essentially die in the field, drying out and turning brown so they can be processed. Spraying the crops with the herbicide hurries the drying and dying along, which is how EWG suspects that the chemical is ending up in some of our favorite foods.

Back in April, the consumer watchdog group US Right to Know discovered that the FDA has been aware of this issue and conducting their own tests for at least two years, based on emails published in The Guardian. But government data was never released to the public, so EWG did a little testing of its own.

Monsanto—which merged with the pharmaceutical company Bayer AG earlier this year—still argues that the claims of harmful side effects of human consumption, particularly as a cause of cancer, are based on “junk science,” and maintains that Roundup-treated crops are safe for human consumption. Both the World Health Organization and the state of California classify glyphosate as a chemical known to cause cancer.

Quaker defended the safety and quality of its products (many others of which were mentioned in the report), stating that it's common practice for farmers industry-wide to apply glyphosate pre-harvest. They added that the levels EWG found in their samples were still “significantly below any regulatory limits” for human consumption. (To which EWG already fired back, "Legal is not the same as safe.")