‘Safe’ levels of Monsanto herbicide and GM crop linked to cancer

19-Sep-2012 - Last updated on 24-Jul-2013 at 10:26 GMT

Exposure to low levels of the genetically modified crop could result in a ‘greatly increased’ risk of tumors’ and premature death, say French researchers.

Long term exposure to even relatively low levels of Monsanto’s herbicide Roundup and a genetically modified resistant crop strain could result in a ‘greatly increased’ risk of tumors’ and premature death, according to new findings in rats.

The new findings are from the first long-term peer reviewed toxicity study into the health impact of a GM tolerant maize crop and the world’s most popular herbicide – Roundup.

Led by a team of French researchers, the two-year study reports that consumption of relatively low ‘safe’ levels of Monsanto’s genetically modified NK603 roundup tolerant maize – or indeed of the herbicide itself – resulted in significantly higher incidence of mammary tumours, kidney and liver damage, and premature death in laboratory rats.

“The results of the study presented here clearly demonstrate that lower levels of complete agricultural glyphosate herbicide formulations, at concentrations well below ofﬁcially set safety limits, induce severe hormone-dependent mammary, hepatic and kidney disturbances,” said the authors, led by Dr Gilles-Eric Séralini from the University of Caen in France.

Séralini and his colleagues say the findings call into question the adequacy of the current regulatory process for genetically modified foods in Europe – which has been used to license all new industrial chemicals, pesticides and other ‘novel crops’ since the Second World War.

For more expert reaction and analysis to this study please see our follow-up article found here.

Study details

Séralini sand his colleagues explained that all current evidence on the safety of GM crop foods is based on 90-day feeding trials – which is the equivalent to late teenage years/early adulthood in a rat.

As a result, the new trial was designed to study any adverse long-term effects resulting from feeding rats on relatively low levels of the commercial GM maize NK603 and Roundup, both individually and combined. The study lasted approximately two years – thus covering the entire lifespan of the rats.

Doses of Roundup started within the range of levels permitted by regulatory authorities in drinking water and as chemical residues in GM feed, whilst doses of NK603 were consistent with those used in previous Monsanto studies, said the authors.

The study reports that even consumption of even the low levels regarded as safe by regulators resulted in serious health problems – but these only became apparent when the rats were older than 90 days. The first tumour was observed after 120 days, but Séralini revealed that the majority were only detected after 18 months.

“Similar degrees of pathological symptoms were noticed in this study to occur from the lowest to the highest doses suggesting a threshold effect,” said the authors.

They added that the findings correspond to levels ‘likely to arise’ from consumption or environmental exposure including the consumption of genetically modified crops or exposure to contaminated drinking water that falls within the authorized limits.

“The results of the study presented here clearly demonstrate that lower levels of complete agricultural glyphosate herbicide formulations, at concentrations well below officially set safety limits, induce severe hormone-dependent mammary, hepatic [liver] and kidney disturbances.”

Source: Food and Chemical Toxicology
Published online ahead of print, doi: 10.1016/j.fct.2012.08.005
“Long-term Toxicity of a Roundup Herbicide and a Roundup-Tolerant Genetically Modified Maize” Authors: Gilles-Eric Seralini, Emilie Clair, Robin Mesnage, Steeve Gress, Nicolas Defarge, et al.