Report finds weed killer ingredient in popular breakfast foods that could increase cancer risk.

The Environmental Working Group (EWG), has found traces of a controversial herbicide in Cheerios, Quaker Oats and other breakfast foods.

The report comes amid longstanding debate about the safety of the chemical glyphosate. The organization that conducted the study, said Wednesday that glyphosate was found in all but five of 29 oat-based foods that were tested.

Glyphosate is the active ingredient in Monsanto’s Roundup, the most heavily used pesticide in the United States. Every year, according to the EWG, more than 250 million pounds of glyphosate is sprayed on American crops.

The World Health Organization has determined that glyphosate is “probably carcinogenic to humans” and the Environmental Protection Agency (EPA) has set a safety level for the potentially dangerous chemical. Just last week, Monsanto was ordered by a court to pay nearly $300 million to a man who claims his terminal cancer was caused by exposure to Roundup. Hundreds of other cases are working their way through the courts.

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