Ask TreeHugger: Does An Organic Diet Matter?


Question: I only buy organic foods for my family, even though it is more expensive. I’ve always assumed that this reduces my family’s exposure to pesticides, but recently read in the news that this isn’t true. Does it?

Response: Yes, with qualifications.

Organic foods are essentially free of pesticides, while nearly every type of conventional fruit and vegetable has at least one type of pesticide applied to it sometime from when the seeds are put into the ground to when they are sold. Logically then, eating organic foods rather than conventional foods will reduce your family’s exposure to pesticides. The qualifications relate to the amount and importance of that reduced exposure.

The amount of the reduction in pesticide exposures will, of course, depend on what your family eats. The best scientific studies of pesticide exposures from foods suggest that an organic diet will basically eliminate one microgram of pesticides that would otherwise be eaten on a conventional diet in a typical day. [Putting this microgram into perspective is difficult, but for what it’s worth, a person eating 1,800 calories a day will typically eat 70 grams (or 70,000,000 micrograms) of fat, while a wasp sting delivers about 2 micrograms of venom. Of course, these comparisons say nothing about their dangers, as the toxicity of the pesticides differs tremendously from that of the fat and venom.]

The impact of switching to an organic diet is illustrated by a Seattle, Washington study, in which 23 children ate non-organic foods on the first three days and last seven days of the study. On the days in between, the children ate organic fruits and vegetables in addition to conventional meat and dairy products. During the first and third stages of the study, every one of the children had measurable amounts of pesticide metabolites (which are the less toxic break-down products of pesticides) in their urine. During the second organic fruit and vegetable stage, the amount of metabolites for two common pesticides chlorpyrifos and malathion was about ten times lower than the conventional diet periods.

Whether these lower levels translate into less health risks is not known, since pesticide metabolite levels during both the organic and non-organic diet periods were lower than US EPA limits. Also, these lower levels do not consider pesticide exposures that occur through the air, soil, indoor dust and water. Although its contribution varies by pesticide and by person, for the average person, food is only a minor contributor to exposures many common pesticides, including chlorpyrifos (used mostly on cotton, corn, almonds, and orange and apple fruit trees) and permethrin (used mostly on cotton, wheat, corn, alfalfa, and poultry). For example, in one scientific study, food accounted for only a few percent of total exposure to chlorpyrifos, while breathing indoor air contributed more than 80%. As a result, it is quite possible that a diet of organic foods will have only a modest effect on total exposure to pesticides.

That said, a growing number of scientific studies have shown that exposures to even small amounts of pesticides are harmful, especially to young children – which I think provides a pretty persuasive reason for you to keep buying organic food. A steady organic food diet is a good and relatively easy way (costs notwithstanding) to lower your risks from pesticides.

Basic information about organic food can be found in the weekly TreeHugger Green Basics column., while information about your fellow organic food buyers can be found in this Treehugger Food and Health post.

Previous Ask Treehugger columns can be found here.

Helen Suh MacIntosh is a professor in environmental health at Harvard University and studies how pollution behaves in the environment and how it affects people's health. Please keep in mind that her answers are just her interpretation of available information and should not be taken as the only viewpoint or solution to a problem. Use this column at your own risk. Having said this, please feel free to post any of your environmental health questions to Helen@TreeHugger.com. (Please use a descriptive email subject line and mention if you want to remain anonymous or not).

Tags: Boston | Diet | Massachusetts | Pesticides

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