After more than 40 years of widespread use, new scientific tests show formulated weedkillers have higher rates of toxicity to human cells This article was originally published in  The Guardian. By Carey Gillam US government researchers have uncovered evidence that some popular weedkilling products, like Monsanto’s widely-used Roundup, are potentially more toxic to human cells than their active ingredient is by … Weedkiller Products More Toxic Than Active Ingredient, Tests Show