Monday, May 20, 2013

On Pesticides


Pesticides are used to kill or control the organisms that damage crops. Herbicides, fungicides, disinfectants, and rodent poisons all fall under this umbrella. These chemicals are widely used in commercial agriculture to maximize efficiency in production.

Although pesticides are applied externally, they can accumulate in the edible tissues of the plants we eat. According to the EPA, “studies show that pesticides can cause health problems, such as birth defects, nerve damage, cancer, and other effects that might occur over a long period of time…pesticides also pose unique health risks to children.” 


Last month, The Environmental Working Group (EWG) released its annual Shoppers Guide to Pesticides in Produce. The document is based on USDA tests of pesticide contamination in 48 popular produce items, and ranks these items accordingly. From this list comes the well-known “Dirty Dozen”: the 12 most pesticide-laden fruits and veggies of 2013, and “The Clean 15- the produce least likely to test positive for pesticide residues”.

Through their annual guide, The EWG “aims to give consumers confidence that... they can buy foods with fewer types of pesticides and lower overall concentrations of pesticide residues.”  On their website, the EWG also provides videos including an interview with Dr. Alex Lu of Harvard.

Dr. Lu enumerates the health risks of pesticide exposure, particularly to children. He notes that children are “the most vulnerable population” to pesticide exposure because they are still growing, and lack many adult mechanisms of detoxification. Dr. Lu goes on to say, “I would recommend families look into information provided by  The Environmental Working Group…to select foods to buy organically or [to determine] when conventional would be fine.”


But is conventional ever fine? How exactly does the EWG detect and rank pesticide contamination, and what qualifies as “clean”? 

To compare the 48 fruits and veggies of interest, The EWG considered six measures of contamination:

1. Percent of samples tested with detectable pesticides
2. Number of pesticides found on a single sample
3. Maximum number of pesticides found on a single sample
4. Percent of samples with two or more detectable pesticides
5. Average number of pesticides found on a single sample
6. Total number of pesticides found on the commodity

Fruits that made The Clean 15 list did not test positive for more than four types of pesticides, and vegetables rarely had more than one type of pesticide residue. 

To me, that doesn’t count as clean. Relative to the dirty dozen, the clean 15 are much less likely to contain a diverse array of pesticides, but they’ve still been sprayed with poison. This list is problematic because it implies that these 15 items don’t need to be purchased from organic growers. As Dr. Lu says, The EWG is providing consumers with a comparative method to decide when it’s necessary to buy organic.


Realistically, ALL produce should be grown organically. Even root crops and fruits with protective outer skins can accumulate pesticides internally. Chemicals leach into groundwater and can enter our waterways as runoff, even for foods that made The Clean 15 list this year.

I agree that The EWG’s aim to “give consumers confidence [to] buy foods with fewer types of pesticides and lower overall concentrations of pesticide residues” is useful, but we must consider what binaries like “The Dirty Dozen” vs. “The Clean 15” imply to consumers in the big picture of building a more sustainable society. 

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