When my son was a baby, organic was a synonym for edible. If the apples I found at the grocery store weren’t certified, I wasn’t buying them. I knew that conventional produce could harbor traces of pesticides, and I’d read that pesticides could affect brain development. Sure, the details of this association were hazy—I didn’t know how many pesticides my son might ingest from Shoprite strawberries, nor did I know whether that amount would do him any harm. But in a way, it didn’t matter: Shelling out a bit more cash to minimize the risks, whatever they were, seemed worth it to me.
Fast-forward two years and my son is eating Shoprite strawberries for breakfast. I support the principles of organic farming, for sure, but it can be hard to consistently pay $7 for a pint of something he’ll go through in two days. Plus, I can’t help but wonder whether giving my son organic food really makes a difference to his health, considering that he’s been known to lick the bottom of his shoes, kiss my poop-sniffing dog, and eat crackers—someone else’s—off of the preschool floor.
Instead of continuing to wonder, I decided to dig into the literature and talk to toxicologists, horticulturists, risk experts, and nutritionists to find out whether the chemicals in conventionally farmed foods could truly pose a risk to my child. What I’ve discovered has totally surprised me—let’s just say I’m going to be a little more relaxed about what I serve kid No. 2.
I want to start off by saying that this column is not about whether organic agriculture is worth supporting for its environmental benefits (I think it is) or whether we as a society should care about the chemicals found in our foods and household products (I think we should). This column is about whether it’s worth buying organic produce for your kids specifically because you think the pesticides on conventional produce could harm them. (If you’re curious about the importance of feeding your kids organic dairy products, meats, and eggs, you’ll have to wait because I’m going to tackle that in another column.)
I’m also not going to spend much space addressing the recent debate over whether organic produce has higher concentrations of beneficial nutrients than conventionally-farmed produce does. James McWilliams already did a good job of discussing the nuances of that issue in Slate; from the research, it seems fairly clear that organic fruits and veggies don’t hold a major nutritional edge over conventional ones except in that they may contain fewer nitrates and more vitamin C, but there’s little evidence that these differences translate into actual health benefits. It’s also difficult to broadly compare the nutrients found in organically versus conventionally grown foods because geography and individual farm practices can impact growth drastically.
So let’s focus on that other major claim about organic food—that is it’s healthier, particularly for kids, because it contains fewer pesticides. First, let’s start with the fact that organic does not mean pesticide-free. As scientist and writer Christie Wilcox explains in several eye-opening blog posts over at Scientific American, organic farmers can and often do use pesticides. The difference is that conventional farmers are allowed to use synthetic pesticides, whereas organic farmers are (mostly) limited to “natural” ones, chosen primarily because they break down easily in the environment and are less likely to pollute land and water. (I say “mostly” because several synthetic chemicals are approved for use in organic farming, too.)
The assumption, of course, is that these natural pesticides are safer than the synthetic ones. Many of them are, but there are some notable exceptions. Rotenone, a pesticide allowed in organic farming, is far more toxic by weight than many synthetic pesticides. The U.S Environmental Protection Agency sets exposure limits for the amount of a chemical that individuals (including kids) can be exposed to per day without any adverse effects. For Rotenone, the EPA has determined that people should be exposed to no more than 0.004 milligrams per kilogram of body weight per day. Let’s compare this toxicity to that of some commonly used synthetic pesticides, like the organophosphate pesticide Malathion. The nonprofit Pesticide Action Network calls organophosphates “some of the most common and most toxic insecticides used today.” (Sarin, the nerve gas used in two Japanese terrorist attacks in the 1990s, is a potent organophosphate.) Yet the EPA has deemed it safe, based on animal tests, for humans to be exposed to 0.02 milligrams of Malathion per kilogram of body weight per day. This is five times more than the amount deemed safe for Rotenone. In other words, by weight, the natural pesticide Rotenone is considered five times more harmful than synthetic pesticide Malathion. The EPA’s recommended exposure limit for Glyphosate, another widely used synthetic pesticide—you might know it as Roundup—is 0.1 milligrams per kilogram per day, which means it’s 25 times less toxic by weight than Rotenone. The synthetic pesticide Captan is 32.5 times less toxic than Rotenone, and another one, Pyrimethanil, is 42.5 times less toxic than Rotenone. Rotenone is also not the only natural pesticide that out-ranks synthetic pesticides in terms of toxicity. The pyrethrins, a class of pesticides derived from chrysanthemums that are approved for use in organic farming, are more toxic by weight than Roundup, Captan, and Pyrimethanil, too.
It’s only fair to directly compare toxicities if people are being exposed to similar amounts of these synthetic and natural pesticides. Many organic farmers use pesticides as a last resort—so in theory, exposures to natural pesticides should be low. (Conventional growers don’t use pesticides unless they have to, either, though; spraying is expensive.) The problem is that farmers often “have to use a lot of the natural pesticides because they break down faster,” explains Linda Chalker-Scott, a professor of horticulture and landscape architecture at Washington State University. “One of the benefits of some of the more traditional synthetic pesticides is that they have been manufactured to be more effective at lower doses.”
Indeed, in a 1989 report, researchers at McGill University grew apples using either a mixture of organically approved natural pesticides, including a mixture of Rotenone and pyrethrins, or a synthetic pesticide called Imidan. They found that, using the natural pesticides, they could achieve a 75 percent yield on their apples only if they sprayed the fruit at least six to seven times throughout the growing season; using the synthetic pesticide, they could get a 90 percent yield with just four sprays. Another more recent study compared the efficacy of two natural pesticides to two synthetic pesticides and found the organic ones to be much less effective against aphids (plant lice) than the synthetic ones. Since organic farmers may have to spray crops more frequently with natural pesticides, it’s not crazy to think that organic produce could sometimes have just as much, if not more, pesticide on it—natural pesticide, yes, but remember that natural isn’t intrinsically safe—compared to conventional produce.
Ah, but what about all those studies that suggest that organic fruits and veggies harbor fewer pesticide residues than conventionally farmed produce does? Those studies only tested for synthetic pesticides. In the few studies that have also looked for natural pesticides—the USDA’s Pesticide Data Program tested for them on organic lettuce in 2009, the California Department of Pesticide Regulation tested a handful of organic fruits and vegetables for certain natural and synthetic pesticides in 2010, and the USDA did an analysis of organic produce in 2010—scientists have found that between 15 and 43 percent of organic produce samples harbor measurable traces of either natural or synthetic pesticides or both. As far as I can tell, however, no one has published a comparison of the overall amounts of both types of pesticides on organic versus conventional produce, so it’s hard to conclude much from these findings other than that, yes, organic produce can be pesticide-tainted, too.
So now the question is: Are these pesticides harmful to your kids? As any toxicologist will tell you, it’s the dose that makes the poison. In other words, just because both conventional and organic produce are sometimes laced with pesticides doesn’t necessarily mean that they’re doing anyone any harm. And an analysis of the numbers suggests they’re not. In a 2011 study published in the Journal of Toxicology, Carl Winter, a pesticide and risk assessment specialist at the University of California-Davis, and his colleague Josh Katz took a close look at the fruits and vegetables that topped the Environmental Working Group’s “Dirty Dozen” list—a top 12 list of what the non-profit group considers the most highly contaminated conventionally-grown fruits and vegetables sold in the United States. (This year, apples, strawberries, and grapes topped the list.) Winter was concerned that the EWG’s methodology was flawed; among other things, the non-profit group does not compare actual pesticide levels on fruits and vegetables to the EPA’s exposure limits to estimate true health effects of consumption.