Rounding up Resistance

The other day a friend asked if it was true that the herbicide Roundup (or glyphosate) caused celiac disease. My knee-jerk response was that these days Roundup is blamed for everything from celiac to cancer.  Adding that, as the top selling herbicide in part thanks to genetically modified crops (it was pretty lucrative before GMOs as well), it’s a good target. Particularly for those concerned about GMOs. While I am skeptical about the celiac connection (here is an interesting blog on that subject published last year in Science 2.0,) I think most agree that there is too much Roundup being spread around. Below is a slightly modified excerpt from Unnatural Selection about how we got here in the first place.

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As much as I would prefer my food and clothing to be produced herbicide-free, I am sometimes lured by the lower cost and availability of early-season, conventionally grown strawberries, brilliant red peppers, and ripe avocados. The reality is that our family eats plenty of products grown with herbicides, as do the great majority of consumers in the United States, and Roundup has surely left its mark on our diet. If I had to pick a poison, I’d want it to be the least-harmful for my family and the environment. Roundup’s active ingredient, glyphosate, it is touted as the less-toxic alternative to herbicides like 2,4-D and atrazine (although recent studies are calling its safety into question).[i] Since the 1970s, Roundup has been the go-to herbicide for relatively low toxicity, but its popularity spiked when Monsanto developed the first-ever herbicide-resistant crop—Roundup Ready Soy. The combination created a cropping system. You buy the Roundup Ready seeds and you use the Roundup herbicide. The technology made it easy for growers to use Roundup anytime, anywhere. The crops, says weed scientist and anti-resistance zealot Mike Owen, changed the entire face of agriculture. As farmers across the country adopted resistant crops, Roundup became the number-one herbicide in the country. But, like a rising Hollywood starlet, the herbicide was loved to death. Says Owen, “When Roundup Ready technology became available, growers basically jumped on it like a duck on a June bug.”

Roundup Ready crops dominate farms in the United States, which means that most of us are unwittingly engaged in a marriage of convenience with engineered crops and with Roundup. Two of the top six food crops in the world are soy and corn, and the majority are ready for Roundup. So too are the weeds. Since Roundup’s introduction, one weed species after another has evolved resistance. As a result, the products I buy may carry higher residues of Roundup, because growers must use more to beat back weeds, or perhaps the products contain a hint of 2,4-D, because the growers have resorted to other herbicides. Or they may cost a bit more. We may be far from the farm, but we are all affected by resistance in subtle ways, whether it’s a different cocktail of herbicide residues in our food and water, or the price of a cotton T-shirt. Resistance looms so large that in the summer of 2012, the National Academy of Sciences—the premier scientific organization the United States—gathered together the top agricultural scientists for a summit on herbicide resistance, with an emphasis on preventing the “once in a century” herbicide from going the way of penicillin. In today’s high-tech world, the notion that weedy plants pose a serious threat to humanity seems inconceivable, yet as with viruses, bacteria, and insects, it’s not just about the individual species. Evolution of resistance and its impact on our lives is a manifestation of our modern chemical addiction.

[i]. T. Bohn, M. Cuhra, T. Traavik, M. Sanden, J. Fagan, R. Primicerio, “Compositional Differences in Soybeans on the Market: Glyphosate Accumulates in Roundup Read GM Soybeans,” Food Chemistry 153 (2014): 27-215; Rick A. Relyea, “New Effects of Roundup on Amphibians: Predators Reduce Herbicide Mortality; Herbicides Induce Antipredator Morphology,” Ecological Applications 22 (2012): 634–47; Rick Relyea, “Amphibians Are Not Ready for Roundup,” Wildlife Ecotoxicology (Emerging Topics in Ecotoxicology series) 3 (201): 267–300.

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