Remember when you could buy strawberries only in spring and early summer? How lucky we now are to be able to buy strawberries and pretty much anything else—asparagus, peaches, nectarines, tomatoes—all through those dreary winter months. Right? Well, maybe not. Recently strawberries topped the list of fruits and veggies (pushing apples out of top slot) with the highest level of pesticide residue.

Most any article on health and nutrition emphasizes that readers need to eat fruits and vegetables as the best way to obtain nutrients that support optimum health. But there is a hidden concern—pesticides. Pesticides are a real health risk, according to many experts. “The toxicity most commonly associated with pesticides in animal studies include disruptions in the normal functioning of the nervous and endocrine system, and increased risks of cancer,” writes Dr. Andrew Weil.

According to the Environmental Working Group (EWG) data from the U.S. Department of Agriculture (USDA), strawberries tested in both 2009 and 2014 contained nearly six different pesticides per sample compared to under two per sample for all other produce. California data shows that “nearly 300 pounds of pesticides were applied to each acre of strawberries grown in the state in 2014. Compare this to corn, which is doused with about 5 pounds of pesticides per acre — and is considered to be a pesticide-intensive crop.” (For more, read Michael Pollen’s The Omnivore’s Dilemma.)

So before you grab that stick of celery, you might like to consider which are the top 12 offenders and the top 15 least pesticide-contaminated fruits and veggies.

EWG’s 2016 Dirty Dozen (Buy These Organic)

• Strawberries
• Apples
• Nectarines
• Peaches
• Celery
• Grapes
• Cherries
• Spinach
• Tomatoes
• Sweet bell peppers
• Cherry tomatoes
• Cucumbers

EWG’s 2015 Clean 15 (OK to Buy These Conventional)

• Avocados
• Sweet corn
• Pineapples
• Cabbage
• Sweet peas (frozen)
• Onions
• Asparagus
• Mangos
• Papayas
• Kiwi
• Eggplant
• Honeydew melon
• Grapefruit
• Cantaloupe
• Cauliflower