The paleo diet encourages you to eat organic, non-GMO fruits and vegetables whenever possible, since these are not grown using pesticides and so will not contain any trace chemicals. If you can’t buy all organic produce, try buying organic for the items known as the “Dirty Dozen” (below). This list is published annually by the Environmental Working Group (EWG). The food with the highest pesticide residue is at the top.
On the other hand, the EWG also publishes the “Clean 15” (also below), which lists the items with the least amount of pesticide. These are considered safer to buy conventionally grown. This list starts with the food with the lowest pesticide residue.