Post archive photo from 2000: An agronomic research manager with Monsanto examines a test plot of corn genetically engineered to combat the destructive rootworm pest in the Shenandoah Valley. (Marc Kaufman/The Washington Post)

The two-year, peer-reviewed study, allegedly the first to look at the long-term effects of genetically engineered corn on animals, was published today in the Food and Chemical Toxicology journal. It was backed by the Committee of Research and Independent Information on Genetic Engineering (CRII-GEN), a French nonprofit known for its opposition to GM foods.

In a telephone conference call with U.S. reporters on Wednesday afternoon, Gilles-Eric Seralini, a biologist at Caen University and the study’s lead author, noted that GM animal studies typically conclude after three months, likely because companies behind genetically modified foods don’t want to know the long-term consequences of their products.

“After four months” Seralini said about his own long-term study on 200 rats, “the tumors began.”

“After one year, there was a . . . high increase in the number of tumors,” continued Seralini, who is also the president of CRII-GEN’s scientific board. He said that most of the female rats had two or three tumors.

Tom Helscher, director of corporate affairs for Monsanto, sent a statement that noted more than a 100 peer-reviewed animal studies have confirmed the safety of biotech crops, but added that the company would review the French study ”thoroughly, as we do all studies that relate to our products and technologies.”

Helscher also pointed out that Seralini and his colleagues have made similarly faulty conclusions in the past, notably in 2007 when they analyzed a previously published 90-day animal study about Monsanto maize. The European Food Safety Authority, which reviewed the paper at the request of the European Union, found no merit in Seralini’s report, concluding:

“EFSA considers that the paper does not present a sound scientific justification in order to question the safety of [Monsanto] maize.”

Monsanto may have been rather restrained in its response, but other critics were not.

“[I] can’t figure it out yet,” said Marion Nestle, the Paulette Goddard 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.”

“So even though I strongly support labeling,” Nestle told All We Can Eat, “I’m skeptical of this study.”

The London-based Science Media Centre, which assists reporters when major science news breaks, provided a whole Web page of criticisms from scientists, researchers and professors. Mark Tester, a research professor for the Australian Centre for Plant Functional Genomics at the University of Adelaide told Science Media Centre:

“The first thing that leaps to my mind is why has nothing emerged from epidemiological studies in the countries where so much GM has been in the food chain for so long? 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!”

Seralini deflected many of the study’s criticisms during the conference call on Wednesday, claiming that by necessity the study couldn’t include every scrap of data the scientists recorded. The study’s 200 rats — 100 females, 100 males — were divided into groups of 10 based on their gender, including two control groups that were given plain water and a standard diet that included a non-GM maize.

Six groups (three male, three female) were fed a diet supplemented with Monsanto GM maize in increasing percentages (11 percent, 22 percent and 33 percent), all of their feed corn treated with the Roundup weed-killer. Six other groups were fed in the same increasing percentages of maize, but theirs was not sprayed with Roundup. The final six groups ate the control feed but were given water spiked with different amounts of Roundup, some reflecting the level found in regular tap water.

The female rats appeared to be particularly sensitive to the diets spiked with GM corn, whether with or without Roundup applied, and water spiked with Roundup.

“In females, all treated groups died 2–3 times more than controls, and more rapidly,” the study reported. Overall, 50 percent of the males and 70 percent of the females on the GM diet died prematurely, compared to 30 and 20 respectively in the control group. Interestingly enough, the rats that consumed a diet with higher percentages of GM corn apparently did not get as sick as those with lower doses.

The study sent shock waves through California, where voters will decide in November whether to pass Proposition 37, which will require labeling on all genetically modified foods. The Right to Know campaign immediately latched onto the study’s findings in its lobbying efforts to pass the ballot initiative. The No on 37 campaign issued its own statement on the study.

Meanwhile, the Food and Drug Administration, which oversees GM plants in the food system, remained neutral on the report. “We will be in a better position to respond after we have more data and have had time to review the paper,” said Shelly L. Burgess, a spokeswoman for the agency.

According to the USDA’s Economic Research Service, an estimated 90 percent of the corn grown in the United States is genetically modified.

Those are the kind of numbers that seem to get Seralini’s blood boiling. “You don’t even have [GM] labeling in the States, and you are very late in this thinking,” he told reporters on the conference call. “I think the world has to change if we really want to have secure food.”

Further reading:

* The full study as published in Food and Chemical Toxicology (PDF)