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Widely used herbicide tied to cancer

On March 20, 2015, the International Agency for Research on Cancer, a division of the prestigious World Health Organization, announced its assessment of the herbicide glyphosate as “probably carcinogenic to humans.”

While “probably carcinogenic” might not sound too threatening, it’s important to understand that on the IARC’s scale of five assessment levels, it’s just one step below the highest level of “carcinogenic to humans.” The glyphosate assessment should be taken seriously.

It certainly was taken seriously by the giant agrochemical corporation Monsanto, the manufacturer of Roundup, the world’s most widely used herbicide. Glyphosate is the active ingredient in Roundup, and if it were firmly established that glyphosate causes cancer, Monsanto’s stock could crash. Monsanto’s line of Roundup-related products – including major food crops such corn, soybeans and sugar beets that are genetically modified (GM) to be resistant to the herbicide – represents about half the company’s gross margin.

The business model for this critical piece of Monsanto’s profile works as follows: Farmers plant the GM crop seeds, which the company calls “Roundup Ready.” When weeds appear in their fields, the farmers spray them with the herbicide. The weeds die; the Roundup-resistant crops grow.

In 1996, Monsanto introduced Roundup Ready crops. Their use spread quickly. The U.S. Department of Agriculture reports that by 2014, 94 percent of soybean acreage and 89 percent of corn acreage in the U.S. was planted with herbicide-resistant (mostly Roundup Ready) crops.

There was a concomitant per-acre and overall increase in the use of glyphosate (mostly Roundup). The total volume of glyphosate applied annually to the three biggest GM crops – corn, soybeans and cotton – increased tenfold, from 15 million to 159 million pounds between 1996 and 2012.

The increase in glyphosate use has intensified concerns about increased human exposure to the herbicide and its possible negative health effects. An Internet search for “health effects of glyphosate” yields an array of credible, peer-reviewed studies that link long-term exposure of varying doses of the herbicide to sterility, hormone disruption, birth defects, low sperm counts, miscarriages and cancer in laboratory rats.

Studies also have shown that glyphosate can damage human embryonic and placental cells. Although exposure to glyphosate health risks is highest among farm workers, it has increased in the general population, which can ingest small amounts of the herbicide by eating GM foods.

Monsanto and other defenders of the glyphosate/GM crop technology – including some independent and university scientists – have responded by pointing to numerous studies that show that glyphosate is (almost) completely safe, and, perhaps most significantly, that the EPA has not yet regulated it.

The debate will doubtlessly continue. But I’d bet on this: As the use of glyphosate keeps growing, so will the evidence of its adverse health effects at our ecological house.

Philip S. Wenz, who grew up in Durango, now lives in Corvallis, Oregon, where writes about environmental issues. www.your-ecological-house.com.



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