A study in Food and Chemical Toxicology into the health effect of a GM-tolerant maize crop and the herbicide Roundup suggested lab rats developed mammary tumors and were more likely to die prematurely. Science Media Centre issued a press release with some of the concerns by other scientists. Only a few are included, for the full list and quotes go here.

I parsed out the ones I thought most insightful but I am biased toward, you know, science, so calibrate accordingly. And calibrate the French researchers behind this too, since they take being anti-science Europeans to the extreme.

Citation: Gilles-Eric Séralini, Emilie Clair, Robin Mesnage, Steeve Gress, Nicolas Defarge, Manuela Malatesta, Didier Hennequin, Joël Spiroux de Vendômois, 'Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize', Food and Chemical Toxicology, In Press, Corrected Proof, Available online 19 September 2012


•‘All data cannot be shown in one report and the most relevant are described here’ – this is a quote from the paper.
•Small sample size
•Maize was minimum 11% of the diet – not balanced
•No non-maize control?
•No results given for non-gm maize
•For nearly 20 years, billions of animals in the EU have been fed soy products produced from genetically modified soybean, mainly from Latin America. No problems have been reported by the hundreds of thousands of farmers, officials, vets and so on.
•The same journal publishes a paper showing no adverse health effects in rats of consuming gm maize (though this is a shorter 90-day study)
•Statistical significance vs relative frequencies.
•We also have to ask why the rats were kept alive for so long – for humane reasons this study would not have been given approval in the UK.
•In Fig.2, I assume the bars with a zero is for the non-maize control. Those bars don’t looks significantly different from the bars indicating 11, 22, and 33% of GM maize in the diet? Have the authors done stats on their data?"

"In my opinion, the methods, stats and reporting of results are all well below the standard I would expect in a rigorous study – to be honest I am surprised it was accepted for publication." - Prof David Spiegelhalter, Winton Professor of the Public Understanding Of Risk, University of Cambridge

"The full data set has not been made available, but the findings do not contradict previous findings that genetic modification itself is a neutral technology, with no inherent health or environmental risks." - Dr Wendy Harwood, senior scientist, John Innes Centre

"Like most of the GM debate, this work has very little to do with GM. The authors of the paper do not suggest that the effects are caused by genetic modification" - Prof Ottoline Leyser, Associate Director of the Sainsbury Laboratory, University of Cambridge

"No food intake data is provided or growth data. This strain of rat is very prone to mammary tumours particularly when food intake is not restricted." - Prof Tom Sanders, Head of the Nutritional Sciences Research Division, King’s College London

"The first thing that leaps to my mind is why has nothing emerged from epidemiological studies in the countries where so much GM has been in the food chain for so long? If the effects are as big as purported, and if the work really is relevant to humans, why aren’t the North Americans dropping like flies?! - Prof Mark Tester, Research Professor, Australian Centre for Plant Functional Genomics, University of Adelaide

H/T Ian Sample, Guardian science correspondent