Critics in the United States repeatedly point out that food safety testing in not required by regulators and accuse the Food and Drug Administration of being too lenient. Though the administration says all companies marketing GM food submit to a voluntary review, what that means is that companies conduct their own safety reviews and provide the results to the FDA. “The FDA posts the [company’s] review on its Web site. Typically just two or three pages, basically just abbreviating what the company said in its submission about the safety of the crop,” said Doug Gurian-Sherman, of the Union of Concerned Scientists, a group critical of biotech regulations. “Then the FDA sends them a letter saying it’s their responsibility to maintain the safety of the product. All they put up is the review, not the data. As somebody who’s done risk assessments, that’s practically useless.”

In other words, the only information that’s made public is the industry’s own conclusions about its products’ safety, not the data supporting those conclusions. The industry says the science behind its products is proprietary.

Another controversy around GM crops stems from concern over environmental contamination and possible “gene flow”—the transference of genetically modified material between plants, which could diminish biodiversity and destabilize ecosystems. Once this happens, some critics say, it would be impossible to track or stop. But the biotech industry says, again, that there is little evidence that gene flow has led to adverse contamination or to a reduction in biodiversity. They point instead to the environmental benefits of GM crops—less soil tillage and fewer pesticides.

Finally, critics wonder if the promise of higher yield through biotech crops—the promise the industry makes when it says it can help feed the world’s hungry—is attainable. So far, the studies on improved yield are mixed, and because the companies won’t allow independent research on their seeds, it is impossible to test their performance.

In an attempt to resolve these questions, four hundred scientists and researchers from around the world banded together to form the International Assessment of Agricultural Knowledge, Science and Technology for Development, or IAASTD. In 2004, the group launched a sweeping project, involving the World Bank, the United Nation’s Food and Agriculture Organization, the World Health Organization, private-sector companies, academics, and governments, to, among other things, evaluate the role biotechnology could play in alleviating hunger and poverty. After four years, fifty-eight countries (the U.S. not among them) signed on to an executive summary that issued a blow to the biotech industry:

Biotechnology has always been on the cutting edge of change. Change is rapid, the domains involved are numerous, and there is a significant lack of transparent communication among actors. Hence assessment of modern biotechnology is lagging behind development; information can be anecdotal and contradictory, and uncertainty on benefits and harms is unavoidable. There is a wide range of perspectives on the environmental, human health and economic risks and benefits of modern biotechnology; many of these risks are as yet unknown.

But the International Service for the Acquisition of Agri-biotech Applications (ISAAA), representing the industry’s position, published a response that said quite the opposite:

The science is very clear. However, a massive international anti-GMO campaign by many NGO’s has planted the seeds of doubt in the public. There is no evidence to support these “perceived risks” and therefore they have no place in the “evidence-based” IAASTD report.

Amid the conflicting claims and contradictory studies, the biotech industry has consistently relied on one, easily digestible message: Look at all the farmers who use our seeds. Look at all the countries using our technology. This message has, in effect, become a stand-in for the more complicated arguments for GM technology. For example, even before Food, Inc., a documentary highly critical of biotech giant Monsanto, hit theaters last summer, Monsanto posted on its Web site a refutation of several of the film’s claims. The post included this bit of boilerplate: “The sheer numbers of countries, not to mention farmers, who have embraced agricultural biotechnology, suggest that it’s not undue influence but instead useful technology and sound science that have been the deciding factors.”

Georgina Gustin writes about all things food-related for the Metro section of the St. Louis Post-Dispatch. When not in the newsroom or tracking farmers in the hills, she's usually in her kitchen, ruining dinner.