The Washington-based nonprofit Environmental Working Group has released the latest edition of its “Shopper’s Guide to Pesticides in Produce,” a look at fruits and vegetables and their total pesticide loads.

Topping the “Dirty Dozen” list this year was apples, which ranked as the most contaminated produce, jumping three spots from last year. According to the U.S. Department of Agriculture, pesticides showed up on 98 percent of the more than 700 apple samples tested.

Other produce in the top 5 included celery, strawberries, peaches and spinach. Making the “Clean 15” list, produce lowest in pesticides, were onions, sweet corn, pineapples, avocado and asparagus.

Analysts at EWG used data collected from the USDA and the Food and Drug Administration from 2000 to 2009. Produce is ranked based on a composite score, equally weighing six factors that reflect the amount and level of pesticides.

The organization said that most of the samples tested were washed and peeled before testing, so the rankings reflect the amounts of chemicals likely present when the food is eaten.

Click here for the entire list.