Guelph, Ont., Canada-A new University of Guelph study cautions that consumers shouldn’t assume that organic is environmentally friendly. Actually, according to findings by Prof. Rebecca Hallett and her associates, some pesticides can have a higher environmental impact than their chemical counterparts because the organic product may require larger doses. According to Hallett, “It’s too simplistic to say that because it’s organic it’s better for the environment. Organic growers are permitted to use pesticides that are of natural origin, and in some cases, these organic pesticides can have higher environmental impacts than synthetic pesticides, often because they have to be used in large doses.” The study compared the environmental impact and effectiveness of six pesticides in killing soybean aphids, the main pest of soybean crops across North America. A mineral oil-based organic pesticide that smothers aphids and another product containing a fungus that infects and kills insects also were examined. The researchers used the environmental impact quotient, a database indicating impact of active ingredients based on such factors as leaching rate into soil, runoff, toxicity from skin exposure, consumer risk, toxicity to birds and fish, and duration of the chemical in the soil and on the plant. They also conducted field tests on how well each pesticide targeted aphids while leaving their predators – ladybugs and flower bugs -unharmed. “We found the mineral oil organic pesticide had the most impact on the environment because it works by smothering the aphids and therefore requires large amounts to be applied to the plants,” said Hallett.
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