(CBS) – Twenty-one oat-based cereal and snack products popular with children contain traces of glyphosate, the active ingredient in the weed killer Roundup, according to tests from the Environmental Working Group. EWG said the tests found glyphosate levels above what it considers safe for children in all but four of the products.

The 21 products that were tested are made by General Mills, including six varieties of Cheerios and 14 of General Mills’ Nature Valley products, such as Nature Valley granola bars.

General Mills said food safety is a “top priority” for the company, which said it’s working to minimize the use of pesticides on the ingredients it uses. “Most crops grown in fields use some form of pesticides and trace amounts are found in the majority of food we all eat,” the company said in an emailed statement. “Experts at the FDA and EPA determine the safe levels for food products,” which it adheres to, as well as farmers that grow the crops, it added.

The report is the latest from the EWG to detect traces of glyphosate in cereals. The environmental advocacy group found traces of the chemical in dozens of Cheerios and Quaker brand products in October. Glyphosate has been at the center of several high-profile lawsuits alleging the chemical causes cancer. A California jury awarded a couple $2 billion in punitive damages after concluding that sustained exposure to Monsanto’s popular Roundup weed killer led to their cancer diagnoses. Monsanto is now owned by Bayer.

Highest glyphosate levels

The two highest levels of glyphosate were detected in Honey Nut Cheerios Medley Crunch and Cheerios, at 833 parts per billion and 729 parts per billion, respectively, the group said. It considers anything over 160 parts per billion to be unsafe for children.

However, the U.S. Environmental Protection Agency has a far higher threshold for glyphosate content, ranging from 0.1 to 310 parts per million, rather than per billion.

For more stories like this that matter to you, click here to download the News 10 app for free.

Watch live newscasts, get breaking news and sign up for push alerts – download now