Setting off another firestorm in the debate over genetically engineered foods, a team of French scientists unveiled a study Wednesday finding that rats fed Monsanto Co.'s transgenic corn or its blockbuster herbicide, Roundup, had higher rates of tumors and premature death.
The controversial study immediately drew skepticism from researchers in the scientific community and repudiations from the biotechnology industry, which pointed to other studies showing that genetically modified food ingredients are as safe as their conventional counterparts.
At the same time, many researchers and activists said the study's results underscored the need for more stringent testing and regulatory standards. The French government immediately called for a national agency to investigate the study, possibly leading to a ban on importation of the particular corn variety, known as NK603.
The study, published in the peer-reviewed journal Food and Chemical Toxicology, was performed over two years by Gilles Eric Seralini, a professor of microbiology with the University of Caen in Normandy and a former researcher and expert for the French government.
“This was the longest and most detailed experiment every published, not only on a GMO but on a pesticide,” Seralini said in a call with reporters. “The results are alarming.”
Tom Helscher, a Monsanto spokesman, said the company would review the study thoroughly. “Numerous peer-reviewed scientific studies performed on biotech crops to date, including more than a hundred feeding studies, have continuously confirmed their safety, as reflected in the respective safety assessments by regulatory authorities around the world,” Helscher said in a statement.
The study looked at more than 200 rats over two years – the average lifetime of the animal – and observed how they responded when fed various quantities of Monsanto's NK603 corn and water containing Roundup, in a standard diet.
The study revealed that rats fed the corn or Roundup, or both combined, developed tumors or had kidney or liver damage earlier than rats in a control group – and after only 90 days. That, Seralini said, was especially important as most companies and government regulators in the U.S. test for a shorter period.
“Regulatory tests last only three months,” Seralini said. “We discovered the tumors began after that.”
After the study's release Wednesday, scientists began to weigh in on its findings. Some criticized the study's approach, saying the control groups were too small and the number of rats included was too low, making the results unreliable. Some criticized Seralini and his colleagues for failing to reveal the exact composition of the rats' diets and said that the complete data from the experiment was not adequately represented in the study.
Still others applauded the research, saying it went further than any other feeding study.
“We've never done this kind of study before, and we should have been doing it a long time ago,” said Andrew Kimbrell, of the Washington-based Center for Food Safety, a group critical of the regulations surrounding genetically engineered crops. “I've heard for two decades that no one's shown any health impacts with GMO foods. As of September 19, 2012, that's no longer true.”
Many scientists underscored the need for more research and a repeat of the study to confirm the data.
“This study suggests caution," said Doug Gurian-Sherman, of the Union of Concerned Scientists, a group critical of genetically engineered food. “It almost certainly should be replicated.”
Monsanto's corn is designed to withstand applications of Roundup, which allows the crops to survive, while killing weeds. The Roundup Ready system, as it is known, has become the dominant system in American agriculture and is employed on millions of acres around the world.
The system has been widely embraced in the U.S., but continues to be controversial in many parts of the world. Monsanto's Mon810 corn is banned in several countries, including France.