Toxicity of Genetically Engineered Foods
Prof. C Kameswara Rao
Foundation for Biotechnology Awareness and Education,
Bangalore, India krao@vsnl.com, www.fbae.org, www.fbaeblog.org

Genetically engineered (GE) products are the most extensively tested for safety among all feed and foods and their safety has been well established.   The livestock and people of the US are the living testimony for the safety of GE products.   Not even a single case of toxicity from GE products was ever proved.   Nevertheless, the issue of toxicity of GE feed and foods is a potent weapon in the armoury of anti-biotech activists.  .     
Bacillus thuringiensis (Bt) proteins do not get into the cotton fibre, which is most used.   Nor into the seed oil, but may be present in small quantities in the seed cake used as livestock feed.   The critics often claimed that the levels of Bt protein in the Bt plants fall drastically so as to be ineffective against the bollworm, after such short periods as 100 days.   Yet, when convenient, they also claim that the seed is toxic to all life.  
The question of toxicity of GE products is raised in even very improbable, ridiculous and absurd situations.   The latest is the report in the The Hindu (June 25, 2005), that “at least 12 peacocks died today after consuming Bt cotton seeds possibly in a field near Mamidalapalli village, about 80 km from here (Karimnagar),” Andhra Pradesh, India.  (http://www.hindu.com/thehindu/holnus/004200506252101.htm).   The verdict is out even before the post-mortem was conducted to determine the cause of death of the birds.   The report has no other details such as how the birds came to eat Bt cottonseeds or if someone fed them the seed.   The peacocks could not have picked the seed from plants in the cotton field as it is not yet the fruiting season and last season’s cotton has already been marketed.   Was feeding the birds a mischief or the reporting itself?  Peacock is a protected and much romanticized National Bird of India and it is so easy to whip up strong emotions about it in the masses.  
Whole cottonseed is too large for many bird species and birds can eat only ginned cottonseeds, as the cotton fibre on the seed is a protection against bird picking.   The seed coat of both Bt and non-Bt cottonseed contains gossypol, which may have been toxic to the peacocks, but not instantly.   Were peacocks ever safely fed on (non-Bt)cottonseed, earlier?
Many studies were conducted to determine the toxicity of Bt protein on several species of farm birds, both that eat the insects and/or the seed, but no toxicity was ever demonstrated.   But the scientists never imagined that Bt toxicity to the Indian peacock would become an issue.   Even so, there is no reason to believe a) that Bt cottonseeds contain enough protein to kill peacock, and b) that it was toxic to these birds at all.   If it is, it is the first such incident in the toxicology of Bt proteins in over 60 years of use of Bt.  

The argument that genetically engineered (GE) products are toxic erupted with Professor Arpad Pusztai’s interview on a British TV show, ‘World in Action’, on August 10, 1998, where he stated that GM potatoes produced worrying biological changes in rats.  A similar charge, adverse effects on rat kidneys and blood, is being currently circulated in Europe, about the Bt event MON 863 in corn.  

Pusztai and his colleague Professor Stanley Ewen fed rats with GE potatoes containing an insecticidal lectin (GNA, Galanthus nivalis agglutinin) from the snow drop plant.  Lectins are a kind of proteins with an affinity to specific carbohydrates.   Lectins are present throughout the biological world performing several diverse functions, including fighting pests and pathogens.   Most of the plant foods we regularly and safely consume contain lectins.   GNA is known to be non-toxic.   But Ewen and Pusztai claimed that the GE potatoes with the gene for GNA stunted the growth of experimental rats, produced unacceptable changes in the gut and adversely modified their immune system.  

The Rowett Research Institute, Aberdeen, Scotland, where the two researchers worked, was not amused at the adverse publicity the Institute attracted by the controversial TV interview.   An audit Committee appointed by the Institute concluded in October 1998 that Pusztai’s data did not support his conclusions. 

In a letter published in the national press in February 1999, 19 Fellows of Britain’s Royal Society were highly critical of Pusztai’s conclusions.   In May 1999, the Royal Society published a partial 'peer review' of Pusztai's then unpublished research, concluding that the results were based on poorly conducted experiments.   Unmoved, Ewen and Pusztai submitted their final paper to the medical journal Lancet, which published it after its own customary peer review.   A Committee of the Royal Society protested against the publication.   The Biotechnology and Biological Science Research Council of the United Kingdom called Lancet ‘irresponsible’.   In June 1999, the Royal Society published a report of a Committee, which stated that Dr Pusztai had produced no convincing evidence of adverse effects from GM potatoes on the growth of rats or their immune function. The Committee concluded that Pusztai’s experiments were poorly designed, the statistics he used were inappropriate and his results were inconsistent.   It further stated that ‘the only way to clarify Dr Pusztai's claims would be to refine his experimental design and carry out further studies to test clearly defined hypotheses focused on the specific effects reported by him’.   Subsequently, in another report, the Royal Society stated that ‘studies on the results of feeding GM sweet peppers and GM tomatoes to rats, and GM soya to mice and rats, have now been completed and no adverse effects have been found’.

 

The controversy affected Pusztai’s position at the Institute, and resulted in the scientific community itself being divided, for and against Pusztai, not on the validity of his results, but on the treatment he got from his Institute, which he served for very long. 

Recently again, 30 of Britain’s leading scientists, including two Nobel Laureates, accused Lancet of scare mongering and of causing harm to health and wasting millions by publishing unfounded stories on such issues as MMR (measles, mumps and rubella) vaccine, hormone replacement therapy, and GM crops (http://www.gmwatch.org, June 21, 2005; http://www.gmwatch.org/profile1.asp?PrId=113; The Times, June 18, 2005).

A lot of research was conducted on the toxicity of GE products using appropriate models and controls, and none have supported Ewen and Pusztai’s findings.   Nevertheless, Pusztai is the darling of the anti-biotech campaign involving toxicity of GE foods even today.   Currently he is reviewing Monsanto’s data on the toxicity of Bt 10 maize containing their MON 863 event.   Early this week he stated that, from the data "It cannot be presumed that the damage to the rats' inner organs and the animals' blood picture are based on chance. The documents also show that the set-up for the experiments was inadequate and evaluation of the data incorrect. Further investigations are absolutely necessary." (http://www.gmwatch.org, June 22, 2005).  Familiar sentences, though they came from different sources earlier.  

The controversy over GM potatoes does not belittle the great service Arpad Pusztai rendered in the cause of science for over 35 years.  

Pusztai worked on a lectin and not on Bt proteins, both of which were shown to be safe in feed and food.   The Indian anti-biotech arguments repeatedly invoke Pusztai’s now largely unproven work, in the context of GE products, edible or not, and no matter what transgene they contain.   One should not be surprised if the peacock story is used to tell the world that all GE products are poison.