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Column: Judging organics using real science

A shopper browses produce at a grocery store in Loma Linda, Calif.

New York Times (2011)

A shopper browses produce at a grocery store in Loma Linda, Calif.

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.

Fast-forward two years. 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.

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 this is not about whether organic agriculture is worth supporting for its environmental benefits (it is) or whether we as a society should care about the chemicals found in our foods and household products (we should). This is about whether it's worth buying organic produce for your kids specifically because you think the pesticides on conventional produce could harm them.

First, organic does not mean pesticide-free. As scientist and writer Christie Wilcox explains in several eye-opening blog posts 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.

The assumption, of course, is that these natural pesticides are safer than the synthetic ones. Many are, but there are notable exceptions. Rotenone, a pesticide allowed in organic farming, is far more toxic by weight than many synthetics. For example, according to the EPA's recommended exposure limit for Glyphosate, a widely used synthetic pesticide you might know as Round-Up, it is 25 times less toxic by weight than Rotenone.

Many organic farmers use pesticides as a last resort — so in theory, exposures to natural pesticides should be low. But conventional growers don't use pesticides unless they have to, either; 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.

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.

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 in the Journal of Toxicology suggests they're not.

"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," said Carl Winter, a co-author of the study and a pesticide and risk assessment specialist at the University of California-Davis.

And by the way, in none of these studies were the fruits and vegetables 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.

There's another important thing to keep in mind about fruits and veggies: They are chock full of a many naturally occurring toxic compounds — things like flavonoids, hydrogen peroxide and formaldehyde. If you ask experts what all this means, you won't hear anyone say OMG don't eat plants; they are trying to kill us. No, plants are still exceptionally good for us.

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.)

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.

Melinda Wenner Moyer is a science writer based in Cold Spring, N.Y.

© 2014 Slate

Column: Judging organics using real science 01/29/14 [Last modified: Wednesday, January 29, 2014 4:12pm]
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