Bt in mammals

April 2011

Dr. Arpad Pusztai (who was instantly vilified when his research provided evidence of immune-system responses in the gut of rats) focused his science on the gastro-intestinal tract of his experimental animals.

Since the gut is the feed-animal interface and the largest lymphoid (immune-system) tissue of the body, it will be the first organ likely to react to any dietary allergens or other toxins, or a novel microbial flora induced by the diet.

Previously, Pusztai cited four published studies firmly establishing the ability of the Bt toxin generated by MON810 maize to stimulate and modulate the systemic and mucosal immune systems in mammals.

He also points out that the evidence for the survival of Bt toxins in the mammalian digestive tract and internal organs is clear-cut.

This picture was enlarged by published evidence from other laboratories which show that the Bt toxin in MON810 binds to the intestinal wall of mice, and that MON810 has increased levels of a known allergenic protein. All these pieces of evidence are pointing to a risk of adverse reactions from consuming this GM maize.

  • Adapted from 'GM POPULATION CONTROL' first published on GM-free Scotland in December 2008
  • Arpad Pusztai Affidavit 30.08.07 in Toxicity of Bt crops – summary of research worldwide, GM Watch, 10.01.08

Laboratory rats

Aubergine is a widely-eaten traditional food in India.

A Bt-containing aubergine created for the Indian market has been found to have many unexpected and inexplicable qualities. For example, it has 15% fewer calories and a different alkaloid content.

Laboratory rats fed the Bt aubergine had diarrhoea, and reduced liver size.

  • Adapted from 'NON-TARGET EFFECTS' which first appeared on GM-free Scotland in July 2009
  • Sam Burcher, Bt Brinjal Unfit for Human Consumption, Science in Society 41 Spring 2009

Dairy cows

Dairy cows fed the Bt aubergines described above were observed to have increased weight, eat more dry roughage matter and increased milk production, as if they were being treated with hormones.

  • Adapted from 'NON-TARGET EFFECTS' which first appeared on GM-free Scotland in July 2009
  • Sam Burcher, Bt Brinjal Unfit for Human Consumption, Science in Society 41 Spring 2009

Laboratory Mice

An Italian study examined the immune-system of very young and very old mice fed 50% MON810 maize. The 'young' mice were given the test diet at weaning (three-weeks of age) for 30 or 90 days. The 'old' mice were fed the test diet for 90 days at the age of 18-19 months (this is about three-quarters through their expected life-span).

There were no differences noted in any of the usual parameters used to assess safety, such as body weight, food consumed and total white blood cell count. However, significant increases were seen in certain white blood cell-types indicative of an immune response, and biochemicals involved in allergic and inflammatory responses were also significantly higher. The biggest differences were seen in the youngest mice (those fed GM 30 days from weaning) in which there were significant differences in 13 out of 18 groups, and in the oldest mice in which there were significant differences in 6 out of 18 groups. The young mice fed GM for 90 days had a less pronounced reaction (significant differences in 2 out of the 18 groups). The latter may be attributable to a build up of tolerance on repeated exposure, or due to an age-related stronger physiology.

The Italian authors concluded that “the results obtained indicate that the consumption of MON810 maize used in the present study induced alterations in intestinal and peripheral immune response of weaning and old mice.”

  • Adapted from an article on GM-free Scotland, December 2008
  • A. Finamore, intestinal and Peripheral Immune Response to MON810 Maize ingestion in Weaning and Old Mice, Journal of Agricultural and Food Chemistry, November 2008
  • GM Maize Disturbs Immune System of Young and Old Mice, Institute of Science in Society Press Release, 19.11.08

An Austrian study to evaluate three different experimental protocols for studying important aspects of a long-term GM diet on mice was commissioned by the Austrian government. The study was never published, apparently, due to incomplete data. It may, however, be a smoking gun, so it's worth knowing what was tried and what was found:

The three protocols were:
  1. A multi-generational study over four generations continuously fed GM. During this experiment, cumulative effects on reproductive success, the health of key organs, and gene expression were monitored.
  2. A continuous breeding study of the reproductive ability of individual breeding pairs fed GM. During this experiment, the health effects on four successive litters were monitored as the mothers aged.
  3. A life term study on how long mice lived when being fed a continuous GM diet.

The diet of the test mice contained 33% of a commercial GM hybrid maize derived from crossing Bt-toxin-containing 'MON810' maize with 'NK603' maize which has two genes conferring herbicide tolerance. Both GM parental lines have cauliflower mosaic viral promoters within the DNA construct, so the stacked hybrid has a double dose. The maize fed to these mice was not formulated into the commonly used pellets because this process involves heat and pressure which can degrade the proteins present.

The life-term model was considered less useful than the other two protocols since there were no physiological challenges involved, and no differences were revealed in any group.

In the multi-generational study, there were no statistical differences between the litter sizes and pup survival in successive generations. However, evidence of significantly reduced kidney size was found in four out of six experimental groups, and signs of a significantly reduced core metabolism were seen in the liver cells of the GM-fed mice.

Even more ominous results were found in the continuous breeding trial, where significantly fewer and smaller, litters, and reduced early survival were seen in the GM-fed mice by the third and fourth litters. Whereas smaller litters are usually heavier, the GM fed ones were lighter.

Measurements of changes in gene expression in the guts of mice in response to GM chow indicated significant differences in several physiological processes, but the Austrian scientists pointed out that current understanding of the implications of these for health and disease is too limited for conclusions to be drawn.

  • Adapted from 'GM POPULATION CONTROL' which first appeared on GM-free Scotland in December 2008
  • A. Velimirov et al., Biological effects of transgenic maize ND603xMON810 fed in long term reproduction studies in mice, October 2008, Institut fϋr Ernährung, Forschungsinstitut für biologischen Landbau, Vienna
  • GM Maize Reduces Fertility and Deregulates Genes in Mice, Institute of Science in Society Press Release 19.11.08
  • Study shows that genetically engineered maize affects reproductive health in mice, Greenpeace International Press Release 11.11.08
  • Does eating food lower your fertility?, Daily Mail, 12.11.08
  • Austrian Government Study Confirms Genetically Modified (GM) Crops Threaten Human Fertility and Health Safety, Institute for Responsible Technology Press Release 13.11.08
  • Austria withdraws study on the long-term consequences of GM maize,, 26.03.10

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