A study by French researchers claiming ill effects on laboratory rats fed genetically modified corn and given water spiked with herbicide has been rejected by American scientists who have questioned the motives and methods of the authors.

The study was led by Gilles-Eric Seralini, whose book calling biotechnology into question has recently been re-issued. The study said that rats fed a steady diet of feed made from biotech corn developed tumors. In addition, the drinking water of the rats was continuously spiked with glyphosate, the active ingredient in many broad spectrum herbicide products. Glyphosate has a history of safe use in more than 130 countries around the world and favorable environmental characteristics. It binds tightly to most soils making it unlikely to move to groundwater and degrades over time in soil and natural waters, said the scientists.

The scientists also said that numerous studies attest to the fact that the particular stock of rats used in the study are prone to develop tumors before the age of two. The Seralini study ran for about two years. Seralini called the study the first long-term feeding study ever conducted, but according to Dr. Martina Newell-McGloughlin, director of the international biotechnology program at the University of California/Davis, the results of numerous long-term studies have been published with none of the results claimed by Seralini.

“The bottom line is, despite numerous studies in the peer-reviewed scientific literature, and substantial experience with humans and animals around the world consuming biotech crops for over 15 years, there has not been a single substantiated case of negative outcomes or a single documented health problem,” said Newell-McGloughlin.