A recent study claiming that genetically modified corn caused tumors in rats is drawing a chorus of criticism from scientists around the world. European officials say the study was too badly done to support its conclusions.
The debate comes as voters in the U.S. state of California consider whether to require labels on all foods with ingredients from genetically modified organisms, or GMOs.
The pictures are shocking. Rats fed GMO corn for two years grew giant tumors in this study in the journal Food and Chemical Toxicology. Study author Gilles-Eric Seralini at the University of Caen says it shows regulations on the crop are not good enough.
"GM foods have been evaluated in an extremely poor and lax way with much less analysis that we have done," Seralini says.
Eighty percent of the packaged foods on U.S. supermarket shelves contain GMO ingredients, according to the Grocery Manufacturers Association.
California advocates used the new study to say those foods should be labeled. The “Yes on 37” campaign, backing mandatory GMO labeling, in on the ballot in this November’s statewide voter referendum.
However, other scientists immediately found problems with the study, including geneticist Alan McHughen at the University of California at Riverside, an expert with the U.S. National Academy of Sciences.
“First of all, the authors of the study used a line of rats that was genetically predisposed to form tumors in the first place," McHughen says. "So right off the bat the whole study was suspect.”
The European Food Safety Authority found numerous problems with the French study, from not enough control rats to substandard analytical methods.
At the University of California at Davis, toxicologist Alison van Eenennaam questioned the researchers’ motives. “I think it was a cynical ploy to exploit the scientific process to create fear in the minds of consumers.”
Even opponents of genetic engineering agree the study was flawed. Michael Hansen, with the advocacy group Consumers Union, feels long-term studies should be done .
“There should be required safety assessments before these crops are put on the market," Hansen says. "That is not what happens in the United States.”
The U.S. Food and Drug Administration does review voluntary safety assessments that companies submit for new GM crops. They typically include a 90-day rat feeding test for toxicity.
That is the international standard. And the longer studies that have been done have not shown major problems, says UC Davis’s Alison van Eenennaam.
“The science doesn’t show there’s any additional data that wouldn’t already be caught at these 90-day studies,” she says.
Regulators in the U.S. and Europe, as well as the U.N.’s World Health Organization and Food and Agriculture Organization, have concluded that genetically modified products on the shelves today are no more dangerous than products made the usual way, according to UC Riverside’s Alan McHughen.
“All of those, I think, give us the body of scientific evidence to state with a certain degree of confidence that yes, these products are as safe as other products on the market,” McHughen says.
Public confidence in this reassurance will be put to the test in the California referendum this November, when voters decide if GM foods need a special label.