To estimate how dangerous the pesticide exposures from the EWG’s “Dirty Dozen” actually are, Winter and his colleagues analyzed USDA data to determine the average levels of the 10 most commonly found pesticides on each of the 12 conventionally farmed fruits and veggies. They then used other USDA data to estimate the average amounts of each pesticide that individuals typically ingest from each of the 12 fruits and vegetables in a 24-hour period. Finally, they compared those daily exposure estimates to the EPA’s exposure limits for each pesticide.
What did they find? Well, let’s start with apples, which the EWG considers the most pesticide-laden fruit or vegetable out there, and look at the pesticide that is most commonly found on them, called Thiabendazole. Winter and his colleagues found that, each day from conventionally-grown apples and apple-based products, Americans typically consume a dose of Thiabendazole that is 787 times less than the EPA’s recommended exposure limit. Put another way, you’d have to eat as many apples and apple products as 787 Americans eat in a single day combined in order to be exposed to a level of this pesticide that approaches the EPA’s exposure limit.
For other fruits and vegetables, Winter and his colleagues found even less reason to worry. For Captan, the synthetic pesticide most commonly found on conventionally grown strawberries, Americans are exposed to 8,180 times less of the chemical per day than the EPA’s limit. Overall, Winter and his colleagues reported that the EPA’s exposure limits were more than 1000 times higher than the daily exposure estimates for 90 percent of the fruit and vegetable comparisons they made.
Granted, we’re exposed to pesticides through other means, too, and some pesticides may have cumulative effects—but Winter says that even so, Americans won’t be ingesting anything close to the EPA’s limits for any of the pesticides used in U.S. agriculture. (And if you ever did ingest a pesticide at or above the EPA’s limit, you wouldn’t suddenly keel over and die. The agency sets pesticide limits at least 100 times lower than the lowest dose that caused any sign of harm, however minimal, to animals when they were fed that amount every day for most of their lives.) “We have a tremendous amount of data showing that what we’re exposed to in the diet for pesticides is very, very low, and certainly much lower than what would be required to have any even minimal health concern,” Winter says. And by the way, in several of these studies, the fruits and vegetables weren't rinsed with tap water before they were tested, yet research suggests that doing so can reduce pesticide exposures significantly. Rubbing the food during rinsing helps, too.*
In light of all this, what should we make of some of the research suggesting that kids exposed to pesticides are more likely to develop ADHD, lower IQs, and autism? Importantly, the latter two studies did not link pesticide exposure from food to these problems; what they found was that pregnant women who were exposed to high levels of pesticides, either occupationally or because they lived close to farms, were at an increased risk for giving birth to babies who went on to have lower IQs or develop autism. The study linking ADHD to pesticides is potentially more concerning: It found that kids ages 8 to 15 who had 10-fold higher concentrations of a pesticide break-down product in their urine had about 1.5 times the odds of having ADHD. It’s important to note, however, that the study only took a single urine measurement in the kids, so it’s hard to know whether it accurately reflected the children’s usual pesticide exposure or whether the day of testing could have been anomalous. Ideally, for a study like this, you want to track urine pesticide levels multiple times to make sure they’re consistent. One scientist critiqued the study because it did not control for the fact that ADHD often runs in families; if the researchers had done this, he argued, they probably would have found no association between pesticide exposure and ADHD. Finally, the ADHD study focused on the organophosphate pesticides, which are becoming less and less commonly used by U.S. farmers every year.
There’s another important thing to keep in mind about fruits and veggies: They are chock full of many naturally-occurring toxic compounds—things like flavonoids, hydrogen peroxide, and formaldehyde. Research conducted by Bruce Ames, director of the Nutrition & Metabolism Center at the Children’s Hospital Oakland Research Institute, has found that Americans consume about 1,500 milligrams of natural toxins from plants a day, which is approximately 16,000 times more than the 0.09 milligrams of synthetic pesticides we get from food every day. These natural toxins are for real, too: According to Ames’s work, the natural chemicals that are known to cause cancer in animals and are found in a single cup of coffee are about equal in weight to a year’s worth of our exposure to synthetic pesticide residues that are known to cause cancer. In a 1996 report, the National Research Council, a non-profit institution that provides expert advice to the government, noted that “natural components of the diet may prove to be of greater concern than synthetic components with respect to cancer risk,” in part because “synthetic chemicals are highly regulated while natural chemicals are not.”
If you ask Ames or the National Research Council what all this means, you won’t hear anyone say OMG don’t eat plants; they are trying to kill us. It’s Ames’s belief that plants are exceptionally good for us in spite of the fact that they contain high levels of natural toxins—and that we certainly shouldn’t be worried about the minuscule differences in pesticide levels between organic and conventional foods. Indeed, if the research literature is clear about anything regarding fruits and vegetables, it’s that eating more of them—conventional or organic—does good things for the body. One review concluded that the quartile of Americans who eat the most fruits and vegetables, organic or not, are about half as likely to develop cancer compared to the quartile who eat the least. Fruits and veggies may also prevent heart disease and diabetes. A fascinating 2012 study used research-based models to predict what would happen if half of all Americans increased their (conventional) fruit and vegetable intake by a single serving each day; it predicted that doing so would prevent 20,000 cases of cancer a year. When the authors modeled whether this increased intake might pose risks due to the greater pesticide exposure, they concluded that yes, there might be 10 additional cases of cancer every year in the U.S. Put another way, the benefits far, far outweigh the risks.
What all this means for parents is that we should stop worrying so much about whether the apples we buy are organic or conventional—we should just start giving our kids more apples. (And, sure, wash them when you can.) The Environmental Working Group agrees: In the first sentence of the executive summary of its 2013 Shoppers Guide to Produce, the organization points out that “the health benefits of a diet rich in fruits and vegetables outweigh the risks of pesticide exposure.” What’s more, irrational fears over conventionally farmed produce can introduce dangerous trade-offs. As University of Michigan decision psychologist Brian Zikmund-Fisher put it to me, “If you don’t feed your kid the ‘right strawberry,’ what do you feed him?” I’ve walked into markets with a hungry kid and been so afraid to buy the conventional apple that I’ve gotten him a snack pack of Annie’s Crackers instead. And I know there are parents who buy the Peter Rabbit Organics Fruit Pouches at Starbucks because they don’t know whether the bananas on display are organic. These aren’t smart moves. It is far, far better for your kids’ long-term health to get them in the habit of eating whole fruits and vegetables, regardless of what type of farm they came from, than to give them pretty much anything else to eat, no matter how organic or all-natural it may be.
Correction, Jan. 30, 2014: This article originally misstated that in none of the studies were the fruits and vegetables washed before testing. The USDA's Pesticide Data Program does rinse produce before residue testing. (Return.)
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