Claim: Studies have demonstrated that Monsanto-developed corn contains toxins that cause organ failure in rats and adverse effects in pregnant women.
Example:[Collected via e-mail, May 2012]
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Monsanto has released its first direct-to-consumer product, a GM sweet corn containing Bt toxin, designed to protect the plant by rupturing the stomach of any insect that feeds on it. Monsanto claims the toxin will break down before the corn makes it to your dinner table, but rats fed the GM corn showed organ failure and the toxin has been detected in the bodies of pregnant women.
Origins: The Bt (Bacillus thuringiensis) protein referred to in the above graphic is a naturally occurring one which has been used in agriculture for decades, often by organic growers and more recently in genetically modified (GM) plants. The Bt protein is employed as a repellant that targets a specific species of insect but has no impact on non-target insects, animals or humans. When field insects like European corn borer or corn rootworm larvae feed on the corn plant, the Bt protein causes them to stop feeding on the plants within a few short hours, and then they die within a few days.
According to Monsanto:
For our Bt corn products, we submitted a detailed (typically several hundred pages) document to FDA containing data comparing the composition of the GM plant to the unmodified plant. In addition to information about the biology of the plant and the introduced trait, applicants provide detailed information on the levels of nutrients such as amino acids, fats, proteins, carbohydrates and anti-nutrients to determine if there are any statistically significant differences between the GM plant and unmodified plant which would result in any safety concerns. If the introduced trait encodes a protein (which would be the case in Bt corn), data is provided to compare the sequence to a known database of allergens and toxins and how that protein is digested as a food source. FDA reviews this information, consults with the applicant if additional information is needed, and if all issues are addressed to their satisfaction issues a letter of no concern.
The claim about GM corn causing organ failure in rats stems from articles published in 2009 and 2012 by Dr. Joël Spiroux de Vendômois (et al) which reported the finding of high tumor rates and early mortality in rats fed genetically modified corn and “safe” levels of the herbicide Roundup. However, several food safety authorities and regulatory agencies found the analysis and conclusions of the 2009 article to be flawed and unsupportive of its claims. Moreover, France’s six scientific academies issued a rare joint statement in October 2012 denouncing the latter study as a similarly flawed "scientific non-event" that served to "spread fear among the public that is not based on any firm conclusion":
"This work does not enable any reliable conclusion to be drawn," they said, adding bluntly that the affair helped "spread fear among the public." The joint statement — an extremely rare event in French science — was signed by the national academies of agriculture, medicine, pharmacy, sciences, technology and veterinary studies. It was sparked by research published in September  that said rats fed with so-called NK603 corn and/or doses of Roundup herbicide developed tumors.
The academies’ statement said: “Given the numerous gaps in methods and interpretation, the data presented in this article cannot challenge previous studies which have concluded that NK603 corn is harmless from the health point of view, as are, more generally, genetically modified plants that have been authorised for consumption by animals and humans." In withering terms, it dismissed the study as "a scientific non-event."
"Hyping the reputation of a scientist or a team is a serious misdemeanour when it helps to spread fear among the public that is not based on any firm conclusion," the academies said.
The claim about Bt "toxin" having been detected in the bodies of pregnant women stems from a 2011 article by Aziz Aris and Samuel Leblanc published in the journal Reproductive Toxicology. This article was also found to be flawed and unsupportive of the interpretation that ingestion of the Bt protein is harmful to humans:
In 2011 there was some media speculation about a paper published by Aziz Aris and Samuel Leblanc titled ‘Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada.'
A number of methodological and interpretive limitations of this paper limit the relevance of the reported findings and conclusions about food safety. The key limitations include insensitivity of the assay method used and unsubstantiated and invalid assumptions regarding the
source of the Cry1Ab protein in the diets of test subjects. Media speculation arising from this paper has also presented conclusions about the human health relevance of this paper which are not supported by either the paper itself or the broader scientific literature
There have been claims in the media that the paper is proof GM foods are not safe for human consumption.
However, the paper does not discuss the safety implications of finding Cry1Ab in the human body and the authors make no mention of any abnormalities in either the subjects or, in the case of those who were pregnant at the time of the study, the subsequent process of birth or the health of the mothers and babies postpartum.
The Cry1Ab protein, whether ingested via Btk-sprayed conventional or organic crops or GM corn products containing the protein, is safe for human consumption at the levels likely to be found in these sources.
Consumer groups and activists who maintain genetically modified foods may pose environmental and health risks have urged major food vendors to avoid Monsanto's sweet corn. Companies such as Whole Foods, Trader Joe's and General Mills have pledged not to sell or use it, but in August 2012 WalMart Stores confirmed that the company would not restrict sales of the genetically modified corn in its stores.