Environmental Working Group (EWG) has just released an updated list identifying the most pesticide-laden and cleanest conventional produce. To compile the “2014 Dirty Dozen“ and the “Clean 15“ lists, scientists focused on 48 fruits and vegetables. Conventionally-grown apples topped the list of most pesticide-contaminated produce: 99% of apple samples tested positive for at least one pesticide residue, mainly because of chemicals applied to the crop after harvest to prevent them from scalding during storage. Other fruits and vegetables on the negative list are strawberries, grapes, celery, peaches, spinach, cucumbers, cherry tomatoes and potatoes. Single samples of celery, cherry tomatoes, imported snap peas, and strawberries tested positive for 13 different pesticides apiece; a single grape even for 15 pesticides. Kale, collard greens, and hot peppers were frequently contaminated with insecticides which are a particular threat to human health. 65% of all samples analyzed tested positive for pesticide residues. The Clean Fifteen, on the other hand, lists conventional produce with the lowest pesticide levels. Avocados were the cleanest, with only 1% of samples showing detectable pesticides, followed by sweet corn, pineapples, cabbage, frozen sweet peas, onions, asparagus, mangoes, papayas and kiwi. The ranking is based on an analysis of 32,000 samples tested by the US Department of Agriculture and the Food and Drug Administration. EWG analysts used six metrics including, the total number of pesticides detected on a crop and the percentage of samples tested with detectable pesticides. “The lists help people find conventional fruits and vegetables with low concentrations of pesticide residues,” said Sonya Lunder, lead author of the report. “If a particular item is likely to be high in pesticides, people can go for organic.” But the report also charges the U.S. Environmental Protect Agency with failing to comply with legislation designed to warn Americans of the risk of eating foods containing chemical pesticides.