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Sunday, September 26, 2010

Chemicals You Can't Wash Off

Systemic pesticides are chemicals that are actually absorbed by a plant when applied to seeds, soil, or leaves. The chemicals then circulate through the plants tissues, killing  the insects that feed on them. Use of these pesticides on food crops began in 1998, and has steadily increased during the past 10 years. Unlike traditional pesticides, you can't wash or peel off systemic pesticide residues because  they're in the  plant's tissues  not on their  exteriors.

  The  four main  systemics used on food crops are members of the nitroguanidine/neonicotinoid group of chemicals. They have been implicated in the mysterious colony collapse disorder that has killed millions of bees. Imidacloprid can be applied to many veggies including tomatoes and leafy greens right up to the day they're harvested. Thiamethoxam was first approved as a seed treatment for corn in 2002.

Plus these products have been approved for use on most veggie and fruit crops. Clothianidin is used as a seed treatment on canola, cereals, corn and sugar beets and as a soil treatment for potatoes. Dinotefuran can be applied to soil or sprayed on leafy greens, potatoes, and cucumbers. When the Pesticide Action Network reviewed the results of pesticide residue tests conducted by the USDA from 1999 to 2007,numerous samples contained residues of systemic pesticides. For example, 74 percent of conventionally grown fresh lettuce and 70 percent of broccoli samples showed imidacloprid residues.

The U.S. EPA has launched a comprehensive review of the environmental safety of imidacloprid, but we won't know the results until 2014. In February 2009, California's Department Of Pesticide Regulation cited reports of eucalyptus nectar and pollen with imidacloprid levels up to 550 parts per billion, or nearly 3 times the 185 parts per billion needed to kill honeybees. And deadly levels of of these systemic poisons are even showing up in leaf guttation drops. These are water droplets that plants sometime exude.

According to a 2009 report in the Journal Of Economic Entomology, "when bees consume guttation drops, collected from plants grown with neonicotinoid coated seeds, they encounter death within a few minutes." Equally disturbing, it appears that nitroguanidine pesticides can persist in soil for 500 days or more.  Right now, there is no scientific evidence that says foods laced with these pesticides will hurt humans. But when we let a novel, man made chemical loose in the food chain, we can't be certain of what will happen next.  This new contamination of our food supply is yet another reason to grow and buy organic.      

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