The “highly toxic agricultural chemical” is federally allowed to be used on oats and other grains imported to the US, according to the EWG. When applied to oat and grain crops, chlormequat alters a plant’s growth, preventing it from bending over and thus making it easier to harvest, per the EWG. Roundup for Breakfast, Part 2: In New Tests, Weed Killer Found in All Kids’ Cereals Sampled A second round of tests commissioned by the Environmental Working Group found the active ingredient in Monsanto's Roundup weed killer in every sample of popular oat-based cereal and other oat-based food marketed to...