Pesticides: Learning Or Building Bias?
written by Grant
We’ve been thinking and writing about scientific research relating to foods we eat. And here’s something interesting that happened to me in the last couple days.
As much as we’ve talked about bias when we think about which body of research we choose to believe, one thing that hasn’t come up is timing. We all understand the phenomenon where we prefer the version of a song we heard first as a teenager. Play some other artist’s version to us now and it’s just not the same, right? We have a strong bias for the first-heard.
Up to now I must admit I have done very little reading on the topic of pesticide residue on foods we eat. Why? Well, again, my defense mechanism against a complex food world is simplicity…or just dodge the issue. I buy organic, locally grown, integrated pest management fruits and vegetables and figure that’s the safest thing I can do.
So I’m telling you I have very little bias on the matter of grocery store produce and whether there is pesticide residue on it or not.
Then along comes this article from Steve Savage, a plant pathologist, on his Applied Mythology blog, shared with me by a thoughtful big ag farmer:
Savage makes these three points in the article:
- “…the data (ed: from the Agricultural Marketing Service arm of the USDA) demonstrates […] that pesticide residues are only present at very low levels, usually dramatically below the conservative “tolerances” set during the risk analysis by the EPA.”
- The press and the Environmental Working Group (EWG) who publish the Dirty Dozen list each year proclaim loudly that our fruits and produce are pesticide-laden. No comment given in these announcements that the USDA research shows extremely low levels of pesticide residue.
- And how is the USDA partially to blame for this spread of misinformation? Savage says, “What USDA does not do is provide a summary version of the data that is easily digestible by ordinary readers, including typical members of the press.”
So here you have my first and primary exposure to the pesticide residue controversy. I don’t know much about Steve yet, but I have to say he makes very clear and believable points. And I’m almost with him on the idea that, hey, maybe extremely low quantities of pesticide are not harmful. The USDA studies this and deems it so. If I can believe the USDA, I can shop at the grocery store.
Next, I find this in my inbox from a thoughtful small ag farmer who writes for a big ag journal:
The article is written by Henry Miller and Jeff Stier. Stier is a senior fellow at the National Center for Public Policy Research and directs its Risk Analysis Division. Miller’s bio reads, in part: “biomedical scientist; FDA drug regulator; and scholar at Stanford University’s Hoover Institution” and he is a self-proclaimed debunker of the misunderstandings of science and research.
Their points, though presented in a slightly more strident tone than Savage’s, are clear and easy for me to get. Primarily they argue that the amounts of pesticide residue being found are too low to be concerned with and they are exaggerated by the EWG and others:
“EWG’s 2010 list involved levels of pesticides 1,000 times lower than the chronic reference dose (the level of daily exposure likely to be without an appreciable risk of deleterious effects during a lifetime of chronic exposure)”
So three scientific minds reach me in these two articles and I have to say, I’m fairly persuaded. I understand there is pesticide residue, but that it is extremely low. There is even some natural pesticide that the plants themselves produce and some of these may be more harmful. The early exposure bias, like that favorite song I talked about earlier, is creeping in on me and I’m about ready to allow pesticide residues at USDA approved levels. It is very interesting for me to see this process in action in my mind.
So what does the EWG say about dosage? Nothing:
“The EWG’s Shopper’s Guide is not built on a complex assessment of pesticide risks but instead reflects the overall pesticide loads of common fruits and vegetables. This approach best captures the uncertainties of the risks of pesticide exposure. Since researchers are constantly developing new insights into how pesticides act on living organisms, no one can say that concentrations of pesticides assumed today to be safe are, in fact, harmless.”
Hmmm. Emotional argument I would have taken hook, line and sinker before. Gotta say, not too convincing for the scientific-y mind, and this is found on their press release, a good place to be convincing if you ask me. Seems like the EWG needs to address the dosage question directly and that’s basically what Jon Hamilton reports on NPR: Why You Shouldn’t Panic About Pesticide In Produce.
There are nagging questions though:
- Are the USDA’s standards, their “conservative tolerances”, low enough? How do we know?
- What about accumulation or interaction of these pesticides in our bodies?
- What about the effects of these pesticides on our environment? Although the EWG’s efforts with their Dirty Dozen list are clearly focused on consumer consumption, you can’t remove our planet’s health from the equation.
- What about the effects of these pesticides on our farmworkers?
- Is the USDA testing only applicable for average weight adults? If so, what about the impact on smaller body sizes, like, say, kids?
So you see the trajectory of my learning on this topic. Now I need your help. Chime in. What do you know about pesticides in our farming that would add to my learning? How do you feel reading this? Are you convinced one way or the other? Speak up!