Are GM foods harmful or nutritionally less beneficial when compared to conventional or organic foods? Scientists and regulators almost universally say “no.” That’s why a study published this week claiming that GM corn causes cancer in rats is creating such a furor. What’s the story behind the story? Jon Entine, executive director of the Genetic Literacy Project, reports.
Does Monsanto’s Roundup Ready corn (Europeans call it maize) cause health problems? It’s a reasonable question. It’s been asked and answered, at least to the satisfaction of most researchers.
There have been more than 100 peer-reviewed studies over the years—many by independent, non-industry scientists—that have demonstrated the safety of GM crops and food. This study by a team of French researchers in the journal Food and Chemical Toxicology is the first to seriously challenge the scientific consensus—and its release comes just in time to play a disruptive role in the upcoming California vote on Proposition 37, which would require mandatory labeling of all food products that include any biotech component.
In a nutshell, the team of French researchers claimed to have found that rats fed a high dose lifetime diet of Monsanto’s genetically modified corn or exposed to its top-selling weed killer Roundup suffered tumors and multiple organ damage.
Lead researcher Gilles-Eric Seralini of the University of Caen said they found that rats fed a diet containing NK603—a seed variety made tolerant to the spraying of Roundup—died earlier than those on a standard diet. They reported that 50 percent of males and 70 percent of females died prematurely, compared with only 30 percent and 20 percent in the control group.
Considering these controversial findings—out of synch with all of the published research so far showing GM food and crops to be safe and nutritionally equivalent or even superior (as a result of vitamin enhancement) to conventional and organic foods—it’s no surprise that the story exploded on the web. More than 10,000 articles appeared in a matter of hours.
It was euphorically received by anti-GM campaigners around the world who immediately moved to leverage the conclusions. “Setting aside possible health issues, the pervasive use of herbicide-resistant crops in the US is perpetuating a rapidly escalating arms race with insects and weeds that develop a resistance to the industry’s potent poisons as they become more common,” wrote Aviva Shen at Think Progress. The study may also buoy anti-Monsanto food activists who organized 65 protests this past week alone at Monsanto facilities across the country.
The reaction to the report by scientists who are expert in this area has ranged from bewilderment to derision to accusations of research malpractice.
“Even though I strongly support labeling, I’m skeptical of this study,” said Marion Nestle, professor in the Department of Nutrition, Food Studies and Public Health at New York University. “It’s weirdly complicated and unclear on key issues: what the controls were fed, relative rates of tumors, why no dose relationship, what the mechanism might be. I can’t think of a biological reason why GMO corn should do this.”
Mark Tester, a research professor for the Australian Centre for Plant Functional Genomics at the University of Adelaide noted that the findings raised the question of why no previous studies have flagged similar concerns. “If the effects are as big as purported, and if the work really is relevant to humans, why aren’t the North Americans dropping like flies? GM has been in the food chain for over a decade over there—and longevity continues to increase inexorably,” he wrote in a comment emailed to Reuters.
As one researcher noted, for nearly 20 years, billions of animals in the European Union and the United States have been fed soy products produced from genetically modified soybean, mainly from Latin America. Yet, no problems have been reported by the hundreds of thousands of farmers, officials and vets.
The London-based Science Media Centre, which assists reporters when major science news breaks, posted an entire page of criticisms from scientists, researchers and professors. David Spiegelhalter of the University of Cambridge writes that the methods, statistics and reporting of results were all below standard. Among the concerns highlighted:
• The published does not present all the data. “All data cannot be shown in one report and the most relevant are described here’”—this is a quote from the paper, which means that no reader can evaluate the findings, which mean the data may have been cherry picked
• Small sample size. The control group is inadequate to make any deduction. Only 10 rodents some of these develop tumors. Until you know the degree of variation in 90 or 180 (divided into groups of ten) control rodents these results are of no value.
• Maize was minimum 11% of the diet—that’s nor a normal diet for rats and invariably distorted the data
• In Fig. 2, the bars with a zero appears to be for the non-maize control, yet those bars don’t look significantly different from the bars indicating 11, 22, and 33% of GM maize in the diet. The authors do not appear to have done analysis of their data.
• The data from the control group fed non-GM maize is not included in the main figures making it very difficult to interpret the results
• No results given for non-gm maize
• The same journal published a paper showing no adverse health effects in rats of consuming gm maize (though this is a shorter 90-day study)
Wendy Harwood, senior scientist at the John Innes Centre in Norwich, UK, reviewed the study, concluding: “The findings do not contradict previous findings that genetic modification itself is a neutral technology, with no inherent health or environmental risks. These results cannot be interpreted as showing that GM technology itself is dangerous.”
Questions have also been raised about the motivations of the researchers. Anti-GM campaigners regularly mount ad hominem cases against any scientist whose studies conclude that GM foods and crops are safe. A study should rise or fall on its own merits. This one is falling, with a thud. But transparency is also important. Do these study authors have any conflicts or known bias?
The lead author, Gilles-Eric Seralini, known as one of Greenpeace’s favorite and most reliable anti-GM scientists, has been actively campaigning against GM crops since 1997, when he publicly demanded a moratorium on GMOs. He frequently claims that GM foods cause a “slow death” in humans, but cites no evidence to back that up. Seralini’s controversial 2007 study (reproduced in slightly different form in 2009) claiming that biotech enhanced corn caused liver and kidney damage in rats was reviewed by the European Food Safety Agency, which determined it to be statistically flawed.
So where do we go from here? Certainly, regulators and scientists—university based and in industry—should continue to be vigilant when it comes to researching the potential health and environmental impacts of new technologies. But what appears to be sloppy and brazenly politically motivated research serves the interests of no one who genuinely cares about empirically based science. It confuses the public and pushes consumers even more towards the precautionary precipice, where fear rules. Alas, it appears that’s exactly where activists like Seralini are hoping to push us.
The French government has asked the country’s health watchdog to evaluate the findings and various international science groups are sure to engage the debate. This could turn far more ugly.