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Genetically Modified Corn Found Toxic to Animals
3/29/2007
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Study raises questions about oversight of biotech firms’ claims and reliability of regulatory system

by Craig Weatherby



Most biologists have been receptive to genetically modified food crops, seeing nothing inherently dangerous in the process.


They’ve reserved their caution for modifications that could clearly prove damaging to other organisms in the environment, or to consumers.


How is Bt corn created?

Bio-technicians insert selected Bt bacterium DNA into the corn plant's own DNA: the genetic material that controls expression of a plant's or animal's traits.


The genetic package inserted into corn often includes three elements:

  • Bt Cry protein genes kill certain insect pests.
  • Promoter genes control where and how much of the Cry protein a plant produces. Some promoters limit protein production to specific parts of the plant, while others produce protein throughout the plant.
  • Genetic markers allow identification of successful crop transformations.

But research by scientists unconnected to biotech firms have raised some alarms, with some results providing reason for serious concern.


And many farmers who embraced GM cropssuch as herbicide-resistant “Roundup Ready” soybeansearly in the game have found themselves handcuffed to expensive cultivation systems that haven't worked as well as advertised.


One major problem is that regulatory agencies rely heavily on research submitted by biotech companies, which have obvious incentives to provide data that favors their products, and to suppress unfavorable findings or “analyze” it out of existence.

Research supplied by the makers of GM crops is usually unavailable to independent observers, and regulatory agencies charged with reviewing it seem motivated more by the interests of politically potent corporations than by those of farmers and consumers.

Now, the results of a university study in France suggest that one kind of Bt corn approved for human consumption may not be as safe as claimed.

Genetically modified “Bt” corn

Among the best-known and most widely used genetically modified (GM) crops are strains of corn that produce specific bacterial proteins found in a family of common soil-dwelling bacteria called Bacillus thuringiensis or “Bt” for short.


Bt bacterium occur naturally in soils worldwide, and produce crystal-like “Cry” proteins that will kill certain insects whose own digestive enzymes convert the protein into a toxic form.


Before the advent of the technology that permits genetic modification of crops, Cry proteins from Bt bacterium were applied directly to crops.
 
But Cry proteins degrade in sunlight and heat, and cannot cover every part of a plant vulnerable to pests, so they are not as effective as the Cry proteins produced internally throughout a genetically modified plant.

Genetically modified (GM) corn damages rat livers and kidneys

French researchers at the University of Caen conducted a 90-day study in which they fed rats a strain of GM corn called MON863. This GM crop is modified to produce Cry3Bb1: a synthetic version of a Bt protein that kills the corn rootworm pest.


MON863 has been used in animal feeds in Europe since 2005 is approved for human consumption in Australia, China, Japan, Korea, Mexico, the Philippines, Taiwan, and, as of 2006, in the European Union.


The results indicated that feeding rats MON863 corn produced liver and kidney damage, as well as differences in weight gain between the sexes.


Regulatory decisions rest on corporate research

Monsanto is the maker of the Bt corn in question, and has not responded directly to the French findings, which indicate possible flaws in the company’s testing methods, and gaps in the testing regimen.


The biotech giant simply asserted, as it said in a press release, that “…the overwhelming opinion of expert authorities is that MON863 is safe for human and animal consumption.”


This statement is based largely on a rat study conducted by an independent lab, whose results were analyzed and reported by Monsanto.


But some scientists disagree that the study proved MON863 corn safe.

In 2005, an independent expert on biostatistics at the University of Hamburg said this about the statistical design of Monsanto's rat feeding study:

“Significant differences were indeed found in the study, and afterwards were classified as irrelevant. This is as if a marksman had shot at a wall and the rings of a target were drawn around where the shot had made a hole, and it was then maintained he had hit the target dead centre” (Greenpeace 2006).

That same year, the authors of a confidential study prepared on behalf of the Austrian government came to this conclusion: “A complete re-evaluation of the study would be indicated, but as the design and the methods are inadequate, a repetition of the study seems desirable” (Greenpeace 2006).


And the authors of the new French report agree that Monsanto’s data does not bear rigorous analysis. They raised concerns about the statistical methods, the failure to measure the animals' weight changes, and the fact that crucial data from urine tests were allegedly concealed in Monsanto's own reports.


The French study and preceding critiques suggest that we may need independent re-analyses of all GM foods for human consumption, and tougher government oversight of biotech companies’ research and claims... including an insistence on more complete data before approving any GM crop.


If not, the promise of GM cropssuch as higher yields, stronger pest resistance, improved nutritional content, and more, which in some cases have already proved illusorywill be jeopardized.


To many observers, tougher oversight of GM cropsfrom the standpoints of consumer safety, environmental risks, and economic cost-benefitis overdue.


We are not anti-science Luddites… far from it. But to date, the evidence that GM crops are more than an expensive, wealth-concentrating distraction from a better alternativepublicly funded research into sustainable agriculture techniques that do not require costly support systemshas not been compelling.



Sources

  • Seralini GE, Cellier D, de Vendomois JS. New Analysis of a Rat Feeding Study with a Genetically Modified Maize Reveals Signs of Hepatorenal Toxicity. Arch Environ Contam Toxicol. 2007 Mar 13; [Epub ahead of print]
  • Greenpeace. The MON863 case - a chronicle of systematic deception; 2006. Accessed online March 27, 2007 at http://www.greenpeace.org/raw/content/international/press/reports/ mon863_chronicle_of_deception.pdf

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