Strawberries remain at the top of the Dirty Dozena list of the EWG Shopper’s Guide to Pesticides in Producea , with spinach jumping to second place in the annual ranking of conventionally grown produce with the most pesticide residues. EWG’s analysis of tests by the U.S. Department of Agriculture found that nearly 70 percent of samples of 48 types of conventional produce were contaminated with residues of one or more pesticides.