Is glyphosate dangerous? Anti-herbicide campaign on shaky ground

Don Huber, a retired American professor of plant pathology, is currently in Germany on a lecture tour. He is warning people of the consequences of using the broad-spectrum herbicide glyphosate, also known under its brand name Roundup, which is used in conjunction with the cultivation of herbicide-tolerant GM crops. According to Huber, the herbicide leads to malnourished plants, to an increase in plant diseases and to significant declines in yield – claims that his former colleagues at Purdue University (USA) vehemently deny.

Although they share his general observation that glyphosate can make plants more susceptible to individual pathogens, they say that this fact has been known for some time and is also true of other herbicides. Glyphosate has, they say, been used on a large scale for more than 30 years and there are no indications of any general increase in plant diseases or associated yield losses as claimed by Huber.

In Germany, Huber’s claims have fallen on fertile soil among environmental associations and Die Grünen (Germany’s Green Party). They are calling for an immediate suspension of the authorisation for herbicides containing glyphosate, citing findings from a study by Argentinian embryologist Andre Carrasco published in 2010. Carrasco injected glyphosate into frog embryos, which caused the frogs to develop serious deformities. He saw this as proof that glyphosate can also disrupt human embryo development and as evidence that it was responsible for deformities among children in soya-growing areas in Argentina. Carrasco’s experiments and conclusions have, however, been disputed by other scientists. Above all, they doubt whether the high concentrations of glyphosate used in the tests are ever achieved in reality. The German Federal Office of Consumer Protection and Food Safety (BVL), which is responsible for authorising plant protection products in Germany, wrote in October 2010 that Carrasco’s study findings were not relevant for the current risk assessment of glyphosate for humans because of methodological weaknesses and a lack of data.

In response to a minor parliamentary question submitted by the Bündnis 90/Die Grünen parliamentary group at the end of August 2011 on the current risk assessment of glyphosate, the German government said that the data currently available did not justify a suspension or restriction of the authorisation for herbicides containing glyphosate. The government cites numerous animal experiments that have provided no indication of genotoxic or carcinogenic risks associated with glyphosate. Germany’s Federal Institute for Risk Assessment (BfR) expressed a similar view in a statement issued in July 2011.

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