Strawberries contain the most pesticides, while sweet corn and avocados are almost clean, according to an annual report from the Environmental Working Group (EWG). Spinach samples, meanwhile, had an average of twice as much pesticide residue by weight than any other crop.
However, a report by the USDA in 2014 found that "overall pesticide chemical residues on foods tested were at levels below the tolerances established by the Environmental Protection Agency" and were not a safety concern to consumers. Should you avoid the conventional produce on the "dirty dozen" list?
Pesticide use on fruits and vegetables varies from one crop, region, and grower to the next, and buying organic doesn't always guarantee a food will be pesticide-free. This provides a good guide for people who want to consume fewer pesticides but can't afford organic produce. Same with the celery, spinach, peaches, pears and tomatoes you picked up at the supermarket. Pears and potatoes were new additions to the list, displacing cherry tomatoes and cucumbers from last year's list.
The USDA doesn't test every food every year. Though hot peppers do not meet EWG's traditional ranking criteria, researchers found them to be contaminated with insecticides like acephate, chlorpyrifos, and oxamyl that are toxic to the human nervous system.
Spinach made one of the more notable jumps on this year's list, moving from No. 8 to No. 2.
The "Clean Fifteen", on the other hand, were: sweet corn, avocados, pineapples, cabbage, onions, frozen sweet peas, papayas, asparagus, mangos, eggplant, honeydew melon, kiwi, cantaloupe, cauliflower and grapefruit.
Among these 15, avocados and sweet corn were the cleanest - only 1 percent of samples showed any detectable pesticides, while more than 80 percent of pineapples, papayas, asparagus, onions and cabbage had no pesticide residues.
Sweet corn and avocados topped the EWG's Clean Fifteen list of foods with the least amount of pesticides. "This is troubling because there is very little research on the health effects of ingesting multiple pesticides".
Despite washing and even peeling some of the more than 36,000 samples, there was still a total of 178 pesticides found among the produce analyzed by the United States Department of Agriculture.
The annual list is meant to convince shoppers to buy organic when it comes to certain types of produce. Here's what you need to know.