(Beyond Pesticides, December 5, 2009) On November 10, 2008, the Austrian government released a report of long term research showing genetically engineered (GE) corn fed to mice significantly reduced their fertility over three to four breeding cycles within one generation. Similar effects were found in mice fed GE corn and bred over four generations.
The study, “Biological effects of transgenic maize NK603xMON810 fed in long term reproduction studies in mice,” was sponsored by the Austrian Ministry of Health, Families, and Youth, and led by Dr. Jürgen Zentek, Professor of Veterinary Medicine at the University of Vienna.
Three series of experiments were done. The first was a multigeneration feeding trial in which the mice were fed and bred for four successive generations, beginning with the parents that were fed the diets from birth. The second was a multi-cycle breeding trial lasting 20 weeks in which breeding pairs of mice were fed beginning one week prior to co-habitation until the end of experiment, and allowed to go through four breeding cycles in the same generation. The third was a life-term trial involving feeding the mice without breeding from conception (via the pregnant mothers) to their eventual death.
The researchers report that it was not possible to obtain a GE test crop plus parental line from the agro-business companies, which was why the test diets consisting of 33 percent GE corn had to be compared with a non-GE corn variety (also at 33 percent) that was closely related to the GE corn. Both were grown under identical conditions. The GE corn was the transgene hybrid NK603 x MON810 containing three gene cassettes, two conveying glyphosate herbicide tolerance and one insect resistance coding for endotoxin Cry1Ab. The transgenic protein was estimated to be 0.11-0.24 microgram per gram of fresh grain.
In the multigeneration study, the parental generation was fed since birth with either GE or non-GE corn diet, and four generations were bred. Less pups were born in successive generations in both control and GE-fed mice. But the controls tended to do better than GE fed. The average litter size and weight as well as number of weaned pups were greater in the non-GE corn group, although the difference was not statistically significant.
Over all generations, about twice as many pups were lost in the GE group as compared with the control group (14.59 percent vs. 7.4 percent). More litters with eight or more pups were seen in the control compared with GE group. And a greater number of pups were lost at weaning in the GE fed.
Comparison of organ weights did not indicate direct dietary effects in the multigeneration study, except for the kidneys. Kidney weight of females in the GE-fed group were significantly lower in the F2, F3 and F4 generations than controls; and males in the GE-fed group also had significantly lower kidney weight than controls in the F2 generation
The electron microscope investigations revealed differences in the liver cells indicative of reduced core metabolism in the GE-fed mice. In addition, DNA microarray analyses showed important differences in gene expression between both groups fed non-GE corn and the group fed GE corn.
In the multi-cycle breeding trial, the same differences between GE-fed and controls were evident and reached statistically significant levels in the 3rd and 4th litters. There were clearly fewer and smaller litters in the GE-fed mice.
The average number of pups born was always lower in the GE fed but did not reach statistical significance before the 3rd and 4th deliveries. The number of pups at weaning was also always smaller in the GE-fed group. Over all the deliveries, more pups were born in the controls than in the GE group (1035 vs. 844).
Consistent with these findings, the life-term feeding trial showed no significant differences in the average life-span of the GE-fed mice compared with controls.
“This meticulous study suggests that a popular type of genetically engineered corn may harbor fertility-reducing substances,” said Bill Freese, Science Policy Analyst at the Center for Food Safety and co-author of a peer-reviewed study on GE crop regulation. “It’s no surprise to us that U.S. regulators did not catch this. None of our regulatory agencies require any long-term animal feeding trials before allowing genetically engineered crops on the market.”
The Center notes that the GE corn used in the study (NK603 x MON810) was developed by the Monsanto Company, and is sold under the brand names YieldGard (Plus)/Roundup Ready. Monsanto’s figures show that U.S. plantings of this GE corn have exploded in recent years, from just 2.2 million acres in 2002 to 38.2 million acres in 2008. The corn is a so-called “stacked” variety with two traits: the Roundup Ready trait allows the corn to survive direct spraying with Roundup herbicide, while a built-in insecticide kills certain above-ground insect pests.
The Center further notes that U.S. regulators allow biotech companies to cross GE crops at will to develop “stacked” crops with virtually any combination of traits without any regulatory oversight, despite expert warnings that stacked crops may pose special risks.
“This study should serve as a wake-up call to governments around the world that genetically engineered foods could cause long-term health damage,” said Andrew Kimbrell, Executive Director of the Center for Food Safety. “The Center calls upon national and international authorities to place a moratorium on the distribution of GE products for human consumption unless or until their safety can be undeniably established.”
“We hope this study will finally persuade the U.S. Food and Drug Administration to completely overhaul its ”˜rubber-stamp’ regulatory process,” added Mr. Freese. “The FDA must stop letting biotech companies self-certify their GE crops as safe, and instead establish strict, mandatory testing requirements, including long-term animal feeding trials, for every GE crop,” he added.
For more information on GE crops, see Beyond Pesticides Genetic Engineering program page