May 11, 2011
Fresh doubts have arisen about the safety of genetically modified crops, with a new study reporting presence of Bt toxin, used widely in GM crops, in human blood for the first time.
Genetically modified crops include genes extracted from bacteria to make them resistant to pest attacks.
These genes make crops toxic to pests but are claimed to pose no danger to the environment and human health. Genetically modified brinjal, whose commercial release was stopped a year ago, has a toxin derived from a soil bacterium called Bacillus thuringiensis ( Bt).
Till now, scientists and multinational corporations promoting GM crops have maintained that Bt toxin poses no danger to human health as the protein breaks down in the human gut. But the presence of this toxin in human blood shows that this does not happen.
Scientists from the University of Sherbrooke, Canada, have detected the insecticidal protein, Cry1Ab, circulating in the blood of pregnant as well as non-pregnant women.
They have also detected the toxin in fetal blood, implying it could pass on to the next generation. The research paper has been peer-reviewed and accepted for publication in the journal Reproductive Toxicology. The study covered 30 pregnant women and 39 women who had come for tubectomy at the Centre Hospitalier Universitaire de Sherbrooke (CHUS) in Quebec.
None of them had worked or lived with a spouse working in contact with pesticides.
They were all consuming typical Canadian diet that included GM foods such as soybeans, corn and potatoes. Blood samples were taken before delivery for pregnant women and at tubal ligation for non-pregnant women. Umbilical cord blood sampling was done after birth.
Cry1Ab toxin was detected in 93 per cent and 80 per cent of maternal and fetal blood samples, respectively and in 69 per cent of tested blood samples from non-pregnant women. Earlier studies had found trace amounts of the Cry1Ab toxin in gastrointestinal contents of livestock fed on GM corn. This gave rise to fears that the toxins may not be effectively eliminated in humans and there may be a high risk of exposure through consumption of contaminated meat.
"Generated data will help regulatory agencies responsible for the protection of human health to make better decisions", noted researchers Aziz Aris and Samuel Leblanc.
Given the potential toxicity of these environmental pollutants and the fragility of the foetus, more studies are needed, particularly those using the placental transfer approach, they added Experts have warned of serious implications for India. Cottonseed oil is made from seeds of genetically modified cotton and thus Bt toxin may have already entered the food chain in India.
"Indian regulators should be immediately called for detailed toxicological studies to know the extent of contamination of the human blood with Bt toxins coming from cottonseed oil, and also ascertain its long term health impacts," Sharma said.