1.8—Mycotoxins cause reproductive failure

Pigs and cows don’t become sterile from eating GM corn

See Genetic Roulette’s False Claims at Bottom of Page

Analysis of Peer-Reviewed Research:

There is a long history of scientific literature on the topic of reproductive failures in production animals, while there aren’t any papers that link Bt corn consumption to the problems that Smith reports.  Reproductive failures and animal deaths are often the result of toxins in the diet.  Mycotoxins produced by molds (eg. fumonisin, ergot, Aflatoxin B1, zearalenone) present in contaminated feed can cause these kinds of effects. The literature reports that Bt corn has been thoroughly tested in a number of animal species and no ill effects have been observed. The literature also shows that Bt corn is consistently lower in mycotoxins like fumonisin which should improve animal health.  Against this background of evidence it is hard to believe that Genetic Roulette would repeat as fact what is at best a classic example of a mistake in logic called a post hoc fallacy.

1.  The reported reproductive problems have nothing to do with GM corn.

Smith neglects to mention that investigators from Iowa State University (Carr and Munkvold, unpublished; www.iastate.edu/news/releases/02/oct/psuedopreg.shtml) concluded that deaths and reproductive failures were not related to the fact that the corn was genetically engineered Bt corn.  They investigated zearalenone as the most likely cause, however, it was impossible to retrospectively prove this conclusion for certain.  Good science demands direct testing of a hypothesis, something that is very difficult to do when one is confronted with retrospective case studies.  We wonder, however, why Smith failed to advise readers that university researchers doubted that Bt corn was the cause of the reproductive failures.

2.  A common cause of reproductive failure is mycotoxins in the diet.

The most likely source of the reproductive failure in this case was the presence of the potent mycotoxins such as zearalenone and fumonisin in contaminated feed (Carr and Munkvold, unpublished; www.iastate.edu/news/releases/02/oct/psuedopreg.shtml). Zearalenone induced reproductive failure is well documented and is a major source of economic loss in animal agriculture (CAST 2004).  Fumonisins have long been known to cause health problems in a variety of problems in production animals (Ross and others 1992; Bucci, Howard 1996).  We quote from Bucci and Howard: Fumonisin ingestion induces a number of fatal diseases in animals, with the organ specificity being species-dependent. The first animal toxicoses to be characterized were leukoencephalomalacia (“moldy corn poisoning”) in equines and pulmonary edema in swine. Fumonisins additionally produce mild to fatal toxicity in liver, kidney and heart in horses, pigs, cattle, sheep, chickens, ducks, rabbits, rats and mice. We think it is fair to ask why, with explanations such as this readily available in the scientific literature since before the introduction of GM crops, Smith could not find probable cause for reproductive failure without resorting to an unfounded assertion that Bt corn was to blame.

3. Mycotoxins can accumulate during growth as a result of insect damage and during post-harvest storage.

Poor growing and storage conditions are the most commons causes of mycotoxin contamination (CAST 2004).

4. GM corn can actually protect animals from mycotoxins.

Animals fed conventional corn are likely to have more health problems than animals fed Bt corn because Bt corn has been shown to have consistently lower levels of one mycotoxin, fumonisin (Munkvold and others.  1997; Munkvold GP and others 1999; CAST, 2004; Kershen 2006).  When corn is protected from insect damage, as for example by the presence of Bt protein in Bt corn, significantly lower levels of fumonisin are usually present.

5. Friends of the Earth are wrong in claiming that GM corn has more fumonisin.

Realizing that their anti-GM claims about reproductive failure were falling apart, Friends of the Earth changed their story and falsely claimed Bt corn has more fumonisin.  Studies from several countries published in the peer-reviewed scientific literature show that Bt corn protected against boring insects has less fumonisin (Munkvold and others 1997; Munkvold GP and others 1999;CAST, 2004; Kershen 2006).  We believe the claims made by Smith and Friends of the Earth border on criminality and almost certainly exhibit a wanton disregard for human health.  We say this because it is now clear that Bt corn is safer and healthier for consumers to eat and that a switch to insect protected corn could lower rates of neural tube defects (NTD) birth defects as well as those of various types of human cancer (Kershen 2006; Torres and others 2007).  Despite these obvious health benefits Smith, Friends of the Earth, and other activist groups carry on their blind opposition to genetic engineering. It is a logical fallacy, called a post hoc fallacy, to say that if something occurs after another event, it is caused by that event. Logic tells us that if an illness occurs after another event—even if that event has never before occurred—it does not establish a cause and effect relationship between the two.  This is called a post hoc ergo propter hoc fallacy, or post hoc fallacy for short. See also another example of the same post hoc logical fallacy but with a different food safety claim made by Smith.3.8 Cooking high lysine corn won’t produce toxins


Bucci TJ and Howard PC (1996). Effect of Fumonisin Mycotoxins in Animals Toxicol.-Toxin Revs. 15:293-302. Carr J, Carson T and  Munkvold G.  Pseudopregnancy in the pig is not associated with Bt corn.  Unpublished. www.iastate.edu/news/releases/02/oct/psuedopreg.shtml

CAST (2004).  Mycotoxins:  Risks in Plant, Animal, and Human Systems. Council for Agricultural Science and Technology, Ames, Iowa, USA

Kershen DK  (2006). Health and Food Safety:  The Benefits of Bt-Corn. Food and Drug Law J.  61:197-235.

Ross PF, Rice LG,  Osweiler GD,  Nelson PE,  Richard JL and Munkvold GP, Hellmich RL, and Showers WB  (1997).  Reduced Fusarium ear rot and symptomless infection in kernels of maize genetically engineered for European corn borer resistance.  Phytopathology 87:1071–1077.

Munkvold GP and others (1999). Comparison of fumonisin concentrationsin kernels of transgenic Bt maize hybrids and nontransgenic hybrids. Plant Dis. 83:130-138. www.apsnet.org/online/feature/BtCorn/1130-02R.pdf accessed Dec 26 2008.

Torres OA, Palencia E, de Pratdesaba LL, Grajeda R, Fuentes M,  Speer ME, Merrill Jr., AH, O’Donnell K, Bacon CW, Glenn AW, and Riley RT (2007). Estimated Fumonisin Exposure in Guatemala Is Greatest in Consumers of Lowland Maize. 

J. Nutrition.  137:2723-2729. Wilson TM.  (1992) A review and update of animal toxicoses associated with fumonisin-contaminated feeds and production of fumonisins by Fusarium isolates. Mycopathologia 117: 109-114.

Genetic Roulette Falsely Claims:

Farmers report pigs and cows became sterile from GM corn

1. More than 20 farmers in North America report that pigs fed GM corn varieties had low conception rates, false pregnancies, or gave birth to bags of water

2. Both male and female pigs became sterile

3. Some farmers also report sterility among cows and bulls. Genetic Roulette claims that pigs and cows that were fed Bt corn had reproductive problems with some becoming sterile.

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