Why We Still Choose Organic — Even for the Clean Fifteen The Environmental Working Group puts mushrooms on the Clean Fifteen at #14 among fruits and vegetables with the lowest pesticide residues, but this doesn’t mean mushrooms don’t have pesticide residues. The U.S. government’s Pesticide Data Program found residues of the anti-mold pesticide thiabendazole in 54.5 percent of conventionally grown mushrooms. The EPA classifies thiabendazole as likely to be carcinogenic when do