The French author of a study linking a type of genetically modified (GM) maize to higher health risks in rats has dismissed criticism of his research methods, describing the work as the most detailed to date on the subject. He claims that rats fed on Monsanto’s GM maize or exposed to its Roundup weedkiller suffered tumours, multiple organ damage and premature death. But the publication has provoked extreme scepticism from some experts not involved with the study.
In France, the government has asked its health and safety agency to establish the study’s scientific validity and may seek a ban on EU imports of the GM maize. Meanwhile, the European Commission has asked the EU food safety agency (EFSA) to verify the results and report back, possibly by the end of the year.
Eric-Gilles Seralini of the University of Caen and his team gave rats a Roundup-tolerant GM maize, and Roundup dissolved in water, for two years. He reports that female mortality increased, mostly due to large mammary tumours and disabled pituitary function (Food and Chemical Technology, 2012, doi.org/10.1016/j.fct.2012.08.005). Males suffered from liver and kidney problems. ‘This may be due to an endocrine disruption linked to Roundup and a new metabolism due to the transgene,’ he writes. ‘GMOs and formulated pesticides must be evaluated by long term studies to measure toxic effects.’
Michael Antoniou, a molecular biologist at King’s College London, who helped draft the paper, says the findings highlight the need to test all GM crops in two-year lifelong studies. He believes the data are strong enough to withdraw temporarily the approval for marketing of the GM maize, and to revise the safety levels for Roundup.
But Roundup producer Monsanto argues that the study does not meet minimum acceptable standards for this type of research. It states: ‘Critical information about how the research was conducted is absent, and the data presented do not support the author’s interpretations.’
There has been no shortage in researchers coming forward to express strong concerns about the study, particularly about the small sample size – 10 rats per group. ‘There is no proper statistical analysis, and the numbers are so low they do not amount to substantial evidence,’ comments David Spiegelhalter, a specialist in public understanding of risk at the University of Cambridge.
Wendy Harwood, senior scientist at the UK’s John Innes Centre, says: ‘The data from the control group fed non-GM maize are not included in the main figures, making it very difficult to interpret the results. Without access to the full data, we can only say that these results cannot be interpreted as showing that GM technology itself is dangerous.’
Tom Sanders, head of nutritional sciences research at King’s College London, criticises the lack of data on food intake and growth. This strain of rat is prone to mammary tumours, particularly when food intake is not restricted, he says.
However, others have welcomed the findings. Patrick Holden, director for the Sustainable Food Trust, says: ‘This research raises a number of serious issues and it is now essential that...other researchers replicate this study on a larger scale to see if the same results are obtained. This suggests that all currently licensed GM crops should be re-evaluated and that future safety studies in laboratory animals must be conducted over significantly longer periods of time that are equivalent to the animals’ normal lifespan.’
National GM bans ruled illegal
The highest court in the European Union has again confirmed that national bans on GM crops are not legally defendable. The European Court of Justice (EJC) clarified the legal requirements for cultivating GM crops in the EU member states on 6 September. It confirmed that it is unlawful for a member state to ban cultivation of a GM crop that has been authorised at the EU level.
The ruling concerns a GM product approved for cultivation in Europe but which Italian farmers had been preventing from using by Italian authorities. In 2011, the ECJ made a similar decision on the illegal French cultivation ban.