According to the U.S. Department of Agriculture, nearly 20 percent of organic lettuce tests positive for pesticides, particularly a pesticide made by Dow Chemical called spinosad. Organic labeling laws allow naturally occurring chemicals to be applied to crops, so spinosad — which comes from a soil bacterium — can be used in organic farming, although the EPA considers the substance slightly toxic.
Are these naturally occurring pesticides safer than synthetic? According to Jeff Gillman, a professor of nursery management at the University of Minnesota and organic practice expert, it depends on the amount used:
"To control fire blight on the same acre of land," he explains, "I could use a tiny amount of a potent synthetic that has proved safe over the last 50 years, or a much larger amount of an organic pesticide." He demurs on saying which is better, saying, "I want people to know that there are definitely tradeoffs."
Once again, the best answer seems to be buying local produce from growers you trust.
• Check it out: Organic Pesticides: Not An Oxymoron at NPR
Did you know some pesticides were allowed in organic produce? Will this change your buying habits?