Engineered Maize Toxicity Claims Roundly Rebuffed
News Jan 22, 2010
- Andy Coghlan, The New Scientist, Jan 22, 2010
MONSANTO, the giant of genetically modified crops, has for the first time been forced to release raw data from toxicology studies it carried out on three strains of its modified maize. An external analysis of the data claims it shows that eating the maize could result in damage to the liver and kidneys, but this has been dismissed as unsupportable by a government agency and independent toxicologists.
With legal help from Greenpeace and the Swedish Board of Agriculture, researchers at the Committee of Research and Information on Genetic Engineering, a French anti-GM lobby group, forced Monsanto to release the data from studies in which rats were fed with the three varieties of maize for three months.
Two of the maize varieties, MON 810 and MON 863, contain genes for the bacterial Bt protein, which protects against corn borer larvae. The third, NK 603, is resistant to the weedkiller glyphosate. All are widely grown in the US, while MON 810 is the only GM crop grown in Europe, mainly in Spain.
The re-analysis of the data, led by Gilles-Eric Séralini at the University of Caen in France, concludes that the rats showed statistically significant signs of liver and kidney toxicity (International Journal of Biological Sciences, vol 5, p 706).
With each of the three strains of maize, researchers say they found unusual concentrations of hormones and other compounds in the blood and urine of the tested rats, suggesting each strain impaired kidney and liver function. By the end of the trials, the female rats that were fed MON 863 had elevated blood-sugar levels and raised concentrations of fatty substances called triglycerides. Both are potential precursors of diabetes, according to Séralini. And there were further signs that the kidneys of rats fed NK 603 were impaired, he says.
"What we've shown is clearly not proof of toxicity, but signs of toxicity," says Séralini. "I'm sure there's no acute toxicity, but who's to say there are no chronic effects?" He wants longer studies on more species to check for such effects.
Unsurprisingly, Monsanto has refuted the findings, saying they do not demonstrate that there is any risk to the consumer. France's High Council of Biotechnology, too, has said that the study provides no new evidence of toxicity from the three maizes. Independent toxicologists contacted by New Scientist said Séralini's analysis overplays the importance of minor variations that most experienced toxicologists would consider to be random background noise.
The study did not address the environmental concerns associated with GM crops, which have led six European countries to ban MON 810.