A controversial study suggesting that rats fed genetically modified corn were more likely to develop cancer has been retracted by the scientific journal that first published it. The study had been cited by opponents of genetically modified organisms (GMOs) as evidence of their harm, but it was heavily criticized in the scientific community for failing to meet scientific standards. The study, known as the Séralini study after French lead author Gilles-Éric Séralini, was originally published in the November 2012 edition of Food and Chemical Toxicology to a very critical reception. Elsevier, the Massachusetts-based publisher of the journal, announced the retraction after a lengthy investigation into the article’s data and the peer-review process behind its publication. Upon publication of the study, the journal received numerous letters expressing concern over the validity of the study and its use of animals, as well as allegations of fraud. The European Food Safety Authority stated that the study lacked scientific merit. Within weeks, 700 scientists had signed a petition for the authors to release all of their raw data, which they ultimately did with the publishers of the journal. The publisher’s year-long investigation found no evidence of fraud or intentional misrepresentation of data, but did find “a legitimate cause for concern regarding both the number of animals in each study group and the particular strain selected,” according to a publisher statement. Critics said that no significant conclusions could be drawn from the study because it only used 20 rats in each group. The publisher said the sample size was a concern during the original peer-review process, but that the peer review ultimately determined the study still had scientific merit. A more in-depth review of the raw data revealed that no definitive conclusions could be drawn from the small sample size, the publisher said. In addition, the breed of rat used in the study is known to have a high incidence of tumors, to the point that natural variability could explain the higher numbers of tumors among the GMO-fed group. (As many as 70 percent of males and 87 percent of female rats get cancer naturally, according to evolutionary biologist and blogger PZ Myers.) “Ultimately, the results presented (while not incorrect) are inconclusive, and therefore do not reach the threshold of publication for Food and Chemical Toxicology,” the publisher’s statement concluded. The move to retract the study drew both instant praise and criticism to the journal. The European Network of Scientists for Social and Environmental Responsibility (ENSSER) called the retraction “a travesty of science” that appeared to be “a bow to industry.” ENSSER said that the study was a chronic toxicity study and not a full-scale carcinogenicity study, meaning that the Séralini study did not set out to draw any definite conclusions, but instead simply aimed to report observations. The study also did not specifically set out to find tumors, but found an increased rate of tumors regardless, ENSSER said. “The biochemical data confirm the toxic effects, such as those on liver and kidney, which are serious enough by themselves,” ENSSER said. “The tumours and mortality rates are observations which need to be confirmed by a specific carcinogenicity study with higher numbers of rats; in view of public food safety, it is not wise to simply ignore them.” Anti-biotech organization GMWatch called the retraction “illicit, unscientific, and unethical” in a statement. The retraction, they said, violates the publishing guidelines of the Committee on Publications Ethics, of which the journal is a member. Those publishing guidelines give only three circumstances under which a journal should retract a study:
- Clear evidence that the findings are unreliable due to misconduct (e.g., data fabrication) or honest error
- Plagiarism or redundant publication
- Unethical research
“Numerous published scientific papers contain inconclusive findings, which are often mixed in with findings that can be presented with more certainty,” the group stated. “It is for future researchers to build on the findings and refine scientific understanding of any uncertainties.” Others applauded the retraction, saying that the study should never have been published in the first place. “It was clear from even a superficial reading that this paper was not fit for publication, and in this instance the peer review process did not work properly,” wrote David Spiegelhalter, professor at the University of Cambridge. PZ Myers said that scientists have been appalled by the study’s shoddy protocol. “Would you believe that in a study with a control group and multiple experimental groups fed on GMO corn, the authors did not use any statistical tests to tell if there was a significant difference between any of the groups? Let that sink in,” Myers wrote. Séralini himself has said that he is contemplating suing the journal.