Posted 4 years ago on March 26, 2014, 4:04 p.m. EST by LeoYo
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How ''Extreme Levels'' of Monsanto's Herbicide Roundup in Food Became the Industry Norm
Wednesday, 26 March 2014 14:00
By Thomas Bøhn and Marek Cuhra, Independent Science News | News
Food and feed quality are crucial to human and animal health. Quality can be defined as sufficiency of appropriate minerals, vitamins and fats, etc. but it also includes the absence of toxins, whether man-made or from other sources. Surprisingly, almost no data exist in the scientific literature on herbicide residues in herbicide tolerant genetically modified (GM) plants, even after nearly 20 years on the market.
In research recently published by our laboratory (Bøhn et al. 2014) we collected soybean samples grown under three typical agricultural conditions: organic, GM, and conventional (but non-GM). The GM soybeans were resistant to the herbicide Roundup, whose active ingredient is glyphosate.
We tested these samples for nutrients and other compounds as well as relevant pesticides, including glyphosate and its principal breakdown product, Aminomethylphosponic acid (AMPA). All of the individual samples of GM-soy contained residues of both glyphosate and AMPA, on average 9.0 mg/kg. This amount is greater than is typical for many vitamins. In contrast, no sample from the conventional or the organic soybeans showed residues of these chemicals (Fig. 1).
bohn herbicide Crop spraying, South Africa (Photo: Thomas Bøhn) This demonstrates that Roundup Ready GM-soybeans sprayed during the growing season take up and accumulate glyphosate and AMPA. Further, what has been considered a working hypothesis for herbicide tolerant crops, i.e. that, as resistant weeds have spread:
"there is a theoretical possibility that also the level of residues of the herbicide and its metabolites may have increased" (Kleter et al. 2011)1
is now shown to be actually happening.
Monsanto (manufacturer of glyphosate) has claimed that residues of glyphosate in GM soy are lower than in conventional soybeans, where glyphosate residues have been measured up to 16-17 mg/kg (Monsanto 1999). These residues, found in non-GM plants, likely must have been due to the practice of spraying before harvest (for desiccation). Another claim of Monsanto's has been that residue levels of up to 5.6 mg/kg in GM-soy represent
"...extreme levels, and far higher than those typically found" (Monsanto 1999).2
Residues of glyphosate and AMPA in Soybeans
Roundup-levels-in-soybeans-300x258 Figure 1. Residues of glyphosate and AMPA in individual soybean samples (n=31). For organic and conventional soybeans, glyphosate residues were below the detection limit. Seven out of the 10 GM-soy samples we tested, however, surpassed this "extreme level" (of glyphosate + AMPA), indicating a trend towards higher residue levels. The increasing use of glyphosate on US Roundup Ready soybeans has been documented (Benbrook 2012). The explanation for this increase is the appearance of glyphosate-tolerant weeds (Shaner et al. 2012) to which farmers are responding with increased doses and more applications.
Maximum residue levels (MRLs) of glyphosate in food and feed Globally, glyphosate-tolerant GM soy is the number one GM crop plant and glyphosate is the most widely used herbicide, with a global production of 620 000 tons in 2008 (Pollak 2011).3 The world soybean production in 2011 was 251.5 million metric tons, with the United States (33%), Brazil (29%), Argentina (19%), China (5%) and India (4%) as the main producing countries (American Soybean Association 2013).
In 2011-2012, soybeans were planted on about 30 million hectares in the USA, with Roundup Ready GM soy contributing 93-94 % of the production (USDA 2013). Globally, Roundup Ready GM soybeans contributed to 75 % of the production in 2011 (James 2012).4
The legally acceptable level of glyphosate contamination in food and feed, i.e. the maximum residue level (MRL) has been increased by authorities in countries where Roundup-Ready GM crops are produced, or where such commodities are imported. In Brazil, the MRL in soybean was increased from 0.2 mg/kg to 10 mg/kg in 2004: a 50-fold increase, but only for GM-soy. The MRL for glyphosate in soybeans has been increased also in the US and Europe. In Europe, it was raised from 0.1 mg/kg to 20 mg/kg (a 200-fold increase) in 1999, and the same MRL of 20 mg/kg was adopted by the US. In all of these cases, MRL values appear to have been adjusted, not based on new scientific evidence, but pragmatically in response to actual observed increases in the content of residues in glyphosate-tolerant GM soybeans.