The Environmental Working Group  put together two lists, “The Dirty Dozen” and “The Clean 15,” to help  consumers know when they should buy organic and when it is unnecessary.  These lists were compiled using data from the United States Department  of Agriculture on the amount of pesticide residue found in non-organic  fruits and vegetables after they had been washed. The fruits and vegetables on “The Dirty Dozen” list, when  conventionally grown, tested positive for at least 47 different  chemicals, with some testing positive for as many as 67. For produce on  the “dirty” list, you should definitely go organic — unless you relish  the idea of consuming a chemical cocktail. “The Dirty Dozen” list  includes:
 
- celery
- peaches
- strawberries
- apples
- domestic blueberries
- nectarines
- sweet bell peppers
- spinach, kale and collard greens
- cherries
- potatoes
- imported grapes
- lettuce
All the produce on “The Clean 15” bore little to no traces of  pesticides, and is safe to consume in non-organic form. This list  includes: 
 
- onions 
- mango
- avocados
- sweet corn
- pineapples
- sweet peas
- asparagus
- kiwi                                                                
- cabbage
- eggplant
- cantaloupe
- watermelon
- grapefruit
- sweet potatoes
- sweet onions                                                                                                                           
 
                                                                                                                                                                                                                                                                                                                          
 What are some types
of produce more prone to sucking up pesticides  than others? Richard Wiles, senior vice president of policy for the  Environmental Working Group says, “If you eat something like a pineapple  or sweet corn, they have a protection defense because of the outer  layer of skin. Not the same for strawberries and berries.”