Organic Consumers Association Mexico (ACO) announced that samples of Maseca brand white and yellow corn flours tested positive for residues of glyphosate and its main metabolite, AMPA. Glyphosate is the active ingredient in Monsanto's Roundup weedkiller. ACO test results on samples of Maseca white and yellow corn flour, sourced from different regions of Mexico, showed glyphosate concentrations of between 5.14 ppb to 17.59 ppb. Some flour samples tested as high as 94.15% for the presence of genetically modified organisms (GMO).