Strawberries and leafy greens contain the most pesticides of any produce, even after washing them, a report finds

• The Environmental Working Group released a list of fruits and vegetables that contain high levels of pesticides.
• Strawberries, spinach, kale, and collard and mustard greens had the highest pesticide residue, according to the report.
• Avocados, sweet corn, and pineapple were the closest to toxin-free.

Every year, the Environmental Working Group (EWG) comes up with a list of fruits and vegetables that contain the highest levels of pesticides deemed the "Dirty Dozen."

Strawberries and leafy greens have once again topped the list of the dirtiest produce, and that's after washing - the agency prepares each food as a consumer would before testing it for pesticide residue.

Nearly 70 percent of non-organic produce sold in the US contains traces of potentially harmful pesticides, according to the 2021 Shopper's Guide to Pesticides in Produce. However, Insider previously reported that the most commonly detected pesticides on the list occur at levels too low to affect human health.

Still, significant levels of pesticide exposure could pose harm to developing brains. One recent analysis found a link between exposure to organophosphates, one of the most common types of pesticide, and an increase in IQ loss and intellectual disability in children.

Here are some more foods to avoid if you're concerned about pesticide exposure.

Collard greens, mustard greens, and peppers were new to the Dirty Dozen this year

Strawberries have topped the list as the most pesticide-laden fruit for the past six years. EWG testing revealed that 90% of strawberries contained at least one pesticide, and 30% of the crop had traces of 10 or more different toxins.

Spinach came in second, followed by a three-way tie between kale, collard greens, and mustard greens. Some of these greens were found to contain DCPA, a possible cancer-causing agent banned by the European Union in 2009.

Nectarines, apples, grapes, and cherries rounded out the middle of the list. Peaches were in the number eight spot, followed by pears, peppers, celery, and tomatoes.

Most of these fruits and vegetables were on last year's list, but bell and hot peppers were a new addition. Pepper crops hadn't been tested for pesticides since 2011-2012, EWG toxicologist Thomas Galligan told CNN. When they checked the crop last year, scientists found 115 different types of pesticides - the most varied total by a landslide.

Avocados, sweet corn, and pineapple topped the Clean Fifteen

The report also features a "Clean Fifteen" list of fruits and vegetable with the least amount of pesticides. Nearly 70% of those food samples had no pesticide residues at all after washing.

"Multiple pesticide residues are extremely rare on Clean Fifteen vegetables," the EWG report stated. "Only 8 percent of Clean Fifteen fruit and vegetable samples had two or more pesticides."

Avocados had the lowest amount of pesticide residue of all the produce on the list. Sweet corn, pineapple, onions, and papaya also topped the list, followed by frozen peas, eggplant, asparagus, broccoli, and cabbage.

Kiwi, cauliflower, mushrooms, and cantaloupe and honeydew melons rounded out the Clean Fifteen.