The EWG Dirty Dozen: Whoever Said Ignorance is Bliss Definitely Didn't Have Chemistry in Mind

Each year, the Environmental Working Group (EWG) compiles a "Dirty Dozen" list of the produce with the highest levels of pesticide residues on them. The 2013 version was just released this week, framed as a handy shopping guide that can help consumers reduce their exposure to pesticides. Although they do say front and center that it's not intended to steer consumers away from "conventional" produce if that's what they have access to, this strikes me a little as talking out of both sides of their mouth. How can you say that if you really believe that the uncertainties are meaningful enough to create the list, and to do so with the context completely removed? I'm pretty certain the Dirty Dozen preaches to the choir and doesn't change many people's behavior, but the underlying message behind it, while perhaps done with good intentions, to me does some genuine harm regardless. The "appeal to nature" fallacy and "chemophobia" overwhelm legitimate scientific debate, have the potential to polarize a nuanced issue, and tend to cause people stress and worry that's just not all that necessary. This is not hardly going to be a defense of pesticides, but a defense of evidence-based reasoning, and an examination of how sometimes evidence contradicts or complicates simplified narratives. You should eat any fruits and vegetables that you have access to, period, no asterisk.

This latte should not be so happy. It's full of toxins. (Source)

Almost 500 years ago, the Renaissance physician Paracelsus established that the mere presence of a chemical is basically meaningless when he wrote, to paraphrase, "the dose makes the poison." The question we should really be asking is "how much of the chemical is there?" Unfortunately, this crucial context is not accessible from the Dirty Dozen list, because context sort of undermines the reason for this list's existence. When we are absorbing information, it comes down to which sources we trust. I understand why people trust environmental groups more than regulatory groups, believe me. However, one of the recurring themes on this blog is how evidence-based reasoning often doesn't give the answers the public is looking for, whether it's regarding the ability to reduce violent crime by cleaning up lead pollution, or banning BPA. I think a fair amount of the mistrust of agencies can be explained by this disconnect rather than a chronic inability to do their job. However true it may be that agencies have failed to protect people in the past, it's not so much because they're failing to legitimately assess risk, it's for reasons such as not sounding an alarm and looking the other way when we know that some clinical trials are based on biased or missing data. Calling certain produce dirty without risk assessment is sort of like putting me in a blindfold and yelling "FIRE!", without telling me if it's in a fireplace or whether the next room is going up in flames. When 2 scientists at UC Davis looked into the methodology used by the EWG for the 2010 list, they determined that it lacked scientific credibility, and decided to create their own model based upon established methods. Here's what they found: