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For anyone worried about pesticides, the Environmental Working Group -- a major U.S. environmental organization -- has something for you.
It's a list of 45 fruits and vegetables ranked according to the level of pesticide contamination found in U.S. Food and Drug Administration testing.
The "cleanest 12," as EWG calls them, include pineapples, mangoes and avocadoes. Onions, the least contaminated food, is said to have a "pesticide load" of one.
The "dirty dozen" include strawberries, celery and apples. At the top of the list is peaches -- with a "pesticide load" of 100.
"There is a growing consensus in the scientific community that small doses of pesticides and other chemicals can adversely affect people," EWG warns.
This has been a standard message of environmentalism for 40 years. and the public has certainly heard and embraced it.
When researchers ask people what other words come to mind when they say "chemical," they often say "toxic," "poison" and "danger." Chemophobia is rampant.
So I talked to Joe Schwarcz, the director of McGill University's Office for Science and Society. Schwarcz is a professor of chemistry and one of Canada's finest writers of popular science.
At my request, Schwarcz had a look at EWG's guide. It's meaningless, he said.
The fact that a pesticide is detectable on fruits or vegetables tells us almost nothing. How much pesticide residue was found on onions? How much on peaches? That's what's critical.
"Just because something is there doesn't mean that it's doing anything. Amounts matter," Schwarcz says. "Where is the information that the level of pesticide contamination that they're talking about has any relevance to humans?" EWG's "pesticide load" numbers may look like quantities, but they're not. They're only relative measures.
Does it matter that peaches have 100 times the "pesticide load" of onions? If the amount of pesticide residues on onions was significant, it might. Otherwise, no. "A very, very small number times 100 is still a very small number," Schwarcz notes.
Quantities matter. Or as Paracelsus said in the 16th century, "the poison is in the dose." Most of us love the smell of a hot cup of coffee. Well, guess what's in it? "If you sample coffee aroma," Schwarcz says, "you will find over 300 compounds . . . and some of those compounds are known animal carcinogens. So do we worry about smelling coffee? I don't think so." Schwarcz adds that we live in a world that is full of risks, and everything comes down to a risk-benefit analysis: "When we get in a car, we're taking a risk. When we cross the street, we're taking a risk." We accept these risks because the benefit of driving or crossing the street outweighs the danger.
In the same way, we have to consider not only what chemicals might do to us, but also what they do for us.
Dan Gardner, Ottawa Citizen
Published: Tuesday, August 19, 2008
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