Séralini et al. study conclusions not supported by data, says EU risk assessment community

EFSA today delivered its final evaluation of the paper by Séralini et al. which raised concerns about the potential toxicity of genetically modified (GM) maize NK603 and of a herbicide containing glyphosate. In particular, it suggested a link between exposure to these substances and an increased incidence of tumours in rats.

The Authority’s final review reaffirmed its initial assessment that the authors’ conclusions cannot be regarded as scientifically sound because of inadequacies in the design, reporting and analysis of the study as outlined in the paper. Consequently, it is not possible to draw valid conclusions about the occurrence of tumours in the rats tested. Based on the information published by Séralini et al., EFSA finds there is no need to re-examine its previous safety evaluations of NK603 or to consider these findings in the ongoing assessment of glyphosate.

Per Bergman, who led EFSA’s work, said: “EFSA’s analysis has shown that deficiencies in the Séralini et al. paper mean it is of insufficient scientific quality for risk assessment. In addition, several national organisations were independently mandated by Member States to assess this study. These reviews have demonstrated a consensus among  a significant part of the EU risk assessment community that the conclusions of Séralini et al. are not supported by the data in the published paper. We believe the completion of this evaluation process has brought clarity to the issue.”

Broad consensus

EFSA’s final statement considered the independent assessments of the paper by organisations of six EU Member States: Belgium, Denmark, France, Germany, Italy and the Netherlands. Full copies of these evaluations can be found in the annex of EFSA’s statement.

EFSA noted the emergence of a broad European consensus, with the reviewed Member State assessments finding the conclusions of Séralini et al. were not supported by the data presented in the study. Four of the national evaluations found the paper did not provide scientific information that would indicate the necessity to reopen the risk assessment of NK603 or glyphosate. The exceptions were France’s High Council of Biotechnology and  Italy, whose assessments did not examine this issue.

Member States also identified many of the same weaknesses in the methodology and design of the paper as raised by EFSA. Unclear study objectives, the low number of rats used in each treatment group, a lack of detail on the feed and treatment formulation, key information missing on the statistical methods employed and incomplete endpoint reporting were all highlighted by Member State organisations.

Inadequate sample size

In the course of the review process, EFSA had requested Séralini et al. to provide further information on their study documentation. No such material had reached the Authority before publication of this statement. However, on 9 November 2012, Séralini et al. published a general reply to the reactions from across the globe to their paper. After carefully examining the publication, EFSA concluded it provided only a limited amount of relevant information which failed to address the majority of the outstanding questions raised in the Authority’s first statement.

In their ‘Answer to critics’ document, Séralini et al. stated the sample size of their treatment groups was too small to allow them to draw conclusions with regard to long-term carcinogenicity and mortality. EFSA noted this acknowledgement from the authors is inconsistent with the overall conclusions they made in the paper regarding the tumours and mortality.

EFSA’s evaluation of the Séralini et al. article was in keeping with its mission to review all relevant scientific literature for GMO risk assessment. The Authority remains committed to monitoring relevant literature on an ongoing basis to ensure the advice it provides is up to date.

• Final review of the Séralini et al. (2012a) publication on a 2-year rodent feeding study with glyphosate formulations and GM maize NK603 as published online on 19 September 2012 in Food and Chemical Toxicology