WASHINGTON -- A study released Wednesday by French scientists is roiling the debate over California's food labeling initiative because it found that rats fed genetically engineered corn, or fed water with the Roundup herbicide along with such corn, suffered tumors and kidney and liver damage.
Lead scientist Gilles-Eric Seralini, a microbiology professor at the University of Caen in Normandy, called the results "really alarming." He said his study was the first long-term look at the effects of genetically engineered crops.
Other scientists were dubious.
Bob Goldberg, distinguished professor of molecular, cell and developmental biology at the University of California, Los Angeles, and a member of the National Academy of Sciences, called the study "bogus."
"There is not one serious scientist who works in the area of plant genetics who has done anything serious over the last 15 or 20 years who would consider anything less than these crops being perfectly safe," Goldberg said.
The study was published in the journal Food and Chemical Toxicology and backed by CRIIGEN, the Committee for Research and Independent Information on Genetic Engineering.
The scientific group, founded by Seralini, is hostile to genetic engineering.
A November ballot measure in California called Proposition 37 would require labeling of foods with genetically engineered ingredients, affecting most packaged food in the state.
More than 85 percent of U.S. corn and soybean crops are genetically engineered, mainly to resist herbicides.
Stacy Malkan, a spokesman for California Right to Know, the group backing Prop 37, said the most "important and shocking part of it is that this is the first available long-term study" of genetically modified organisms, "which have been in the food supply for the better part of 20 years."
Seralini said rats fed a diet containing a Roundup-tolerant corn -- or given water with Roundup at levels U.S. regulators permit in drinking water or as chemical residues -- died earlier than the rats fed a normal diet.
Fifty percent of males and 70 percent of females died prematurely, compared with 30 percent and 20 percent in a control group, the study found.
It concluded that the corn's genetic modification and the herbicide's endocrine-disrupting effects caused the tumors and organ damage. Seralini said genetically engineered foods could be contributing to cancers and autoimmune disorders.
The French government ordered a review and asked European officials "to take all necessary measures to protect human and animal health, measures that could go as far as an emergency suspension of imports" of genetically engineered corn.
Other scientists criticized the French study, saying the breed of rats used was already prone to tumors, the control groups were far too small and the statistical analysis was flawed.
Henry I. Miller, founding director of the U.S. Food and Drug Administration's Office of Biotechnology and now a fellow at Stanford University's conservative Hoover Institution, called the Seralini study "rubbish."
A vocal supporter of genetic engineering, Miller said the technique used was a more precise form of the traditional plant breeding.
He also said studies using animals more closely related to humans have demonstrated the safety of such crops.