Elsevier has announced that they are retracting the infamous Seralini study which claimed to show that GMO corn causes cancer in laboratory rats. The retraction comes one year after the paper was published, and seems to be a response to the avalanche of criticism the study has faced. This retraction is to the anti-GMO world what the retraction of the infamous Wakefield Lancet paper was to the anti-vaccine world.
The Seralini paper was published in November 2012 in Food and Chemical Toxicology. It was immediately embraced by anti-GMO activists, and continues to be often cited as evidence that GMO foods are unhealthy. It was also immediately skewered by skeptics and more objective scientists as a fatally flawed study.
The study looked at male and female rats of the Sprague-Dawley strain of rat – a strain with a known high baseline incidence of tumors. These rats were fed regular corn mixed with various percentages of GMO corn: zero (the control groups), 11, 22, and 33%. Another group was fed GMO corn plus glyphosate (Round-Up) in their water, and a third was given just glyphosate. The authors concluded:
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. Similarly, disruption of biosynthetic pathways that may result from overexpression of the EPSPS transgene in the GM NK603 maize can give rise to comparable pathologies that may be linked to abnormal or unbalanced phenolic acids metabolites, or related compounds. Other mutagenic and metabolic effects of the edible GMO cannot be excluded.
Sounds pretty scary. Now let’s look at the multiple criticisms:
The biggest criticism of the study is the combination of two features – the small sample size and lack of statistical analysis. The entire study is premised on comparing various dose groups with control groups that were not exposed to GMO or glyphosate. And yet, the authors provide no statistical analysis of this comparison. Given the small number of rats in each group, it is likely that this lack of statistical analysis is due to the fact that statistical significance could not be reached.
In other words – the results of the study are uninterpretable. In the retraction statement Elsevier wrote:
Ultimately, the results presented (while not incorrect) are inconclusive, and therefore do not reach the threshold of publication for Food and Chemical Toxicology.
The retraction reads like a long excuse for the editorial failure of the journal, and is disappointing. But at least they ultimately reached the correct conclusion – this paper should never have been published. It slipped through the cracks of peer review.
- Scientific Journal Retracts Anti-GMO Junk Science Study (illuminutti.com)
- The Seralini GMO Study – Retraction and Response to Critics (sciencebasedmedicine.org)
- Seralini GMO Study Retracted (theness.com)
- Study Linking Genetically Modified Corn to Rat Tumors Is Retracted (scientificamerican.com)