The authors concede that Sprague-Dawley rats may not be the best model for such long-term studies, but argue that the difference between the NK603-fed rats and controls is marked, and that many fewer control rats developed tumors in middle age. The 90-day trial of Monsanto’s NK603 maize used in its authorization also used Sprague-Dawley rats, they add.
José Domingo, a toxicologist at Rovira i Virgili University in Reus, Spain, and a managing editor of Food and Chemical Toxicology, says that the study raised no red flags during peer review. Domingo, who last year authored a critical review of safety assessments of GM plants, has previously complained about the lack of independent feeding studies of GM foods.
The controversy over the findings is likely to be settled only after detailed analysis of the paper and its data, and replication of the experiments. But Séralini says he won’t release his data until the raw data underpinning the authorization of NK603 in Europe are also made public. And he wants all the data to be assessed by an independent international committee, arguing that experts involved in the authorization of the maize should not be involved. EFSA chief Catherine Geslain-Lanéelle disagreed, and said that her agency is well placed to assemble a multidisciplinary group to give an impartial assessment.
Some scientists, however, have long questioned whether such feeding studies are appropriate for testing the safety of whole foods, says Peter Kearns, head of food safety, nanosafety and chemical accidents for the Organization for Economic Co-operation and Development in Paris. They were designed for testing chemicals where precise doses of purified and well-characterized compounds can be administered, whereas compounds in foods are heterogeneous, and doses are difficult to control. Regulators rely mainly on more robust tests that compare the toxicological and nutritional profiles of GM foods with their non-GM counterparts to screen for potential concerns.
Resolution of the debate over the safety of GM foods can come only from rigorous science clarifying the issues, Kearns adds.