“Yes, GMOs are poisons,” screamed the front cover of last week’s issue of the respectable French news weekly, Le Nouvel Observateur. The blatantly fallacious headline was the opening salvo in a blitz of media coverage about research published online in the journal Food and Chemical Toxicology. The paper, from a research group led by Gilles-Eric Séralini, a molecular biologist at the University of Caen in France, claimed to show that consumption of a genetically modified (GM) maize (corn) that had already been approved for animal and human consumption and of the herbicide Roundup greatly elevates rates of cancer and other illnesses, and causes premature deaths, in rats.

With such strong claims and the predictably large effect they will have on public opinion, researchers should take care how they present their findings to the public and the media. They should spell out their results clearly; emphasize the limitations and caveats; and make it clear that the data still need to be assessed, and replicated, by the scientific community.

That didn’t happen. The paper was promoted in a public-relations offensive, with a related book and film set for release this week. Furthermore, journalists wishing to report the research had to sign confidentiality agreements that prevented them from contacting other scientists for comment on the paper until after the embargo had expired. Some, to their credit, refused, or accepted and then revisited the story critically once their hands were no longer tied by these outrageous restrictions.

The result was the exclusion of critical comment in many of the breaking stories — the ones that most people will remember. But much criticism has followed (see page 484). In hindsight, journalists who agreed to the conditions should have contacted the journal publisher — in this case, Elsevier — which no doubt would have done its best to have made the paper available under embargo without such constraints.

The embargo system gives journalists advance access to papers on the premise that it will give them time to research the story fully before presenting it to the public. The system also benefits journals and authors because it helps to maximize press coverage, but at its heart, it is about helping to improve the quality of science reporting. Crucially, the embargo system allows journalists to consult scientists not involved in the work before interpreting it for the public.

The criticisms that followed questioned both the study’s methodology and findings. Given its exceptional claims, the authors of the paper now need to make their raw data available so that they can be carefully assessed by scientists with appropriate expertise, and the work replicated or refuted — thus will the study stand or fall. The European Food Safety Agency, and other advisory and regulatory bodies, are planning to assess the research, and these assessments should be as transparent as possible, so that the public can be confident about whatever they conclude.

The events of last week also illustrate a long-standing flaw in the debate over the safety of GM crops. Many have used last week’s publication to claim that GM foods are a health risk. But even if one GM crop were to be shown to have serious adverse health effects, that would say little about others: the safety of any genetic modification depends on the crop and on the particular changes introduced. Scientists who support transgenic crops fall into the same trap when they claim that the many GM crops that have passed safety tests somehow show that ‘GMOs are safe’. They should instead be giving the message that GM foods must be assessed on a case-by-case basis.

Too often in the GM-food debate, generalizations and extremism lead to sterile public and political discourse that obscures key issues: what sorts of GM crops might bring true benefits to agriculture and consumers; how to avoid monopolization of farming choices; and what types of sustainable agriculture we want in the future. Polarized debates, not GMOs, are the poison to be avoided.