Details of the report, published by the Independent on Sunday in the UK, are alleged to show that rats fed the genetically modified (GM) corn MON 863 developed internal abnormalities, while these health problems were absent from another batch of rodents fed non-GM food as part of the research project.
The controversy comes as the Cartagena Biosafety Protocol summit meets in Montreal this week to discuss issues such as bulk labeling of GM crops and state liability in cases of contamination. Unsurprisingly therefore, food safety campaigners have pounced on the disclosure.
"Monsanto's refusal to hand over animal feeding studies concerning its biotech corn is outrageous,"Bill Freese, research analyst for Friends of the Earth US told FoodNavigator-USA.com.
"I think it's fair to ask: Would Monsanto be hiding its safety studies if it didn't have something to hide?"
He points out that controversy surrounding the rat study was first broken by French daily Le Monde over a year ago, and that Monstanto is still refusing to release the study in its entirety.
Nonethlesess, it appears that this most recent disclosure has hit Monsanto hard. Shares were down 34 cents at $57.66 in early trading on the New York Stock Exchange on Monday. But the US biotech giant insists that it supplied all required information to the European Food Safety Authority (EFSA) prior to EFSA's 2004 favorable scientific opinion on the company's MON 863 corn.
What's more, the company is adamant that there is no new information about MON 863, modified to protect itself against corn rootworm, which has not been submitted to EU regulators.
"That is not the case," said Jerry Hjelle, vice president for Monsanto Worldwide Regulatory Affairs. "Monsanto has provided all required data and studies, including the subject rat study, to European regulatory authorities, and EFSA reviewed these studies before issuing its opinion."
Monsanto said that the product, which has been grown commercially in the United States and Canada since 2003, is safe, and that EFSA's Scientific Panel on Genetically Modified Organisms even published a statement on 29 October 2004 verifying this.
The company insists therefore that the research does not provide evidence of any hidden dangers in biotechnology, only inconsequential differences in kidney size and blood composition in the animals used. It has also defended its right not to disclose the full study as it "could be of commercial use to our competitors and exploited by others for commercial advantage, if made available."
It insists that all the information about its MON 863 maize, which was sent to the Independent on Sunday many weeks ago, is available here.
Monsanto, based in St. Louis, Missouri, is the world's leading developer of genetic modifications for corn, soybeans, cotton and canola. It argues that GM corn resistant to corn rootworm larvae could save US business millions of dollars; the US Department of Agriculture estimates that this pest causes $1 billion in lost revenue annually to the US maize crop.
U.S. farmers have largely embraced new biotechnology. But other countries, notably in the European Union, have been slow to approve the products because of questions about how genetic changes in the plants affect humans and animals.
Monsanto is still seeking approval to import the biotech corn for use in processed foods and derived food products, but the EU's 25 governments remain deadlocked over the issue.