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Evidence too weak to say pesticides linked to cancer – Yet

Last week, headlines heralded a conference in Toronto of health and safety experts, noting that a final link between pesticide use and cancer rates was at hand. In this update from Ridgetown College's John Jordan, the actual picture nearly a week later, is not as clear.


November 18, 2008
By The Canadian Press

November 18, 2008 

Toronto  -It's one of those thorny issues that keeps cropping up among scientists, health-advocacy groups and the public: do the myriad pesticides that farmers use to grow our food cause cancer?

The answer? Nobody is really sure.

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At least that seems to be the consensus of world experts who gathered in Toronto on Wednesday for a two-day conference hosted by the Canadian Cancer Society.

Studies in lab animals exposed to various bug, weed and rodent killers show a few do appear to cause some types of cancer, said Aaron Blair, an expert in occupational pesticide exposure at the US National Cancer Institute.

But figuring out whether the chemicals -both synthetic and naturally occurring – affect people in the same way is harder to pin down, he said. For one thing, studies on humans can look only for possible associations between exposure to a substance and a health outcome like cancer.

While some studies have found an apparent excess of certain cancers, such as lymphomas, in farmers and other populations that have high contact with pesticides, the evidence "is not exactly, completely solid in every respect," Blair said in an interview.

"Now you look at occupational studies that have been carried out in various groups who apply or use or manufacture pesticides, and my take on the evidence is it's, well, maybe or possibly."

But scientists aren't about to leave the question hanging, he said.