A new study finds breakfast food marketed to children contains a weed-killer that some health authorities have linked to cancer. According to independent laboratory tests, popular oat cereals, oatmeal, granola and snack bars come with a hefty dose of the weed-killing poison in Monsanto’s Roundup. The Environmental Working Group published a report from a commissioned laboratory test of 45 products made with oats, including Cheerios, Lucky Charms, Kind bars and Nature Valley bars, finding glyphosate, an herbicide that has been linked to cancer, in nearly all of them. More than two thirds of the samples had glyphosate levels above what EWG scientists consider protective of children’s health with an adequate margin of safety. EWG’s findings raise the prospect that millions of American children are being exposed to a suspected carcinogen at a time when their bodies are rapidly developing.