For years, not only did I recommend the Environmental Working Group’s (EWG) annual “Dirty Dozen” and “Clean Fifteen” lists as a useful guide for prioritizing which fruits and vegetables to buy organic, but I used it as a guide for my own purchases. I’m not a believer in food guilt, but I definitely felt something close to guilt when I bought conventional (non-organic) kale or strawberries. The 2018 updated lists were released April 10, and for the first time I decided to write a dedicated column about them. Accordingly, I dug in and took a deeper look at the methodology behind the list — and was disappointed.
To develop the list, EWG uses data from the U.S. Department of Agriculture’s (USDA) Pesticide Data Program, and the Food and Drug Administration’s (FDA) Pesticide Residue Monitoring Program. The USDA data is more complete, and includes data on pesticide residue for both conventional and organic produce in their ready-to-eat forms. Unfortunately, EWG ignores some of that information.
The Dirty Dozen and Clean Fifteen, and all the points in between, are largely based on how many different pesticide residues are found on samples from each crop. Of the six criteria used — percentage of samples with detectable pesticides, percentage of samples with two or more pesticides, average number of pesticides found on a single sample, maximum number of pesticides found on a single sample, total number of pesticides found on the crop and average amount of all pesticides found — only one (the final one) looks at the total amount.
What these lists don’t factor in is the relative safety or toxicity of the pesticides detected. In other words, a crop that has residues from seven pesticides could rank “dirtier” than a crop with three pesticides, even if those three pesticides have greater potential health risks. Does it matter that one-third of strawberry samples had 10 or more pesticides if those pesticides were present in minuscule amounts and have lower toxicity? We don’t get that information.
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EWG also doesn’t tell you how many pesticide residues were found on comparable organic crops. When people think “organic,” they tend to translate that as “pesticide free.” That’s a myth on two levels. One, there are many pesticides that are approved for use on organic crops. Most are deemed “natural,” but there are 25 synthetic products are also allowed in organic agriculture — a fraction of the 900 or so allowed in conventional agriculture, but still.
Two, due to contamination, most organic produce has detectable levels of not-approved-for-organic pesticides. As long as the residue levels are below 5 percent of the tolerance level set by the Environmental Protection Agency (EPA), they are considered “unintentional,” and the produce can still be sold as organic — in other words, if the tolerance level for a particular chemical pesticide is 0.5 parts per million, then organic produce can’t have detectable levels of more than 0.025 parts per million. What EWG doesn’t tell you is that for the crops on the Dirty Dozen, the majority of pesticide residues on the conventional as well as the organic versions are low enough to be allowed under organic rules. In two cases — potatoes and tomatoes — a higher percentage of the pesticide residues on conventional samples met the “OK for organic” criteria.
The bottom line is that our health benefits from eating adequate fruits and vegetables are most important — don’t let uncertainty about whether to buy organic or conventional scare you away from the produce department. Even EWG agrees: “The health benefits of a diet rich in fruits and vegetables outweigh the risks of pesticide exposure. Eating conventionally grown produce is far better than skipping fruits and vegetables.”