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.
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.
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," said Devinder Sharma,
an anti-GM activist.
最新研究证明转基因植物中广泛存在的Bt毒素会进入人体血液，研究人员并首次在食用转基因食品的人体中发现了Bt毒素，这使有关转基因食品安全性的问题再一次引起了公众注意。
迄今为止，科学家和跨国转基因公司坚称Bt毒素对人体没有危害，因为蛋白质能够在肠道中被分解掉。但现在在人体中发现了Bt毒素，这说明人的肠道并不能完全分解这种毒蛋白。
加拿大谢布克大学的科学家在怀孕妇女及未怀孕妇女血液中均发现了杀虫蛋白Cry1Ab。
他们还在胎儿的血液中检测到了这种毒素，表明转基因毒蛋白能够代代相传。研究报告已通过了同行评估并将刊登于生殖毒理学学刊。共有30名怀孕妇女和39名接受输卵管结扎的女性参与了此项由位于魁北克的护理学院主持的研究项目。
这些接受测试的妇女全都没有接触过杀虫剂，她们的丈夫或同居者也不在和杀虫剂有关的行业工作。她们通常吃的是最典型的加拿大食物，含有转基因的膳食，包括转基因的黄豆、玉米和土豆。血液标本都是在怀孕妇女生产之前和未怀孕妇女接受结扎手术之前采集的。脐带圈的血液标本是在分娩后采集的。
百分之93的母体和百分之80的胎儿的血液中发现有CryiAb毒素，未怀孕妇女中百分之69的人的血液中被发现有这种毒素。更早的一项研究还在被喂食转基因饲料的家畜的肠胃道中发现了Cry1Ab.
这不得不让人担心，我们现在还有杜绝转基因毒素进入人体系统的希望吗。
专家们警告，这项研究结果对印度或许意味着一场灾难。印度人通常食用的棉籽油是用转基因棉花籽加工制作的，由此推断Bt毒素已经进入了印度人的食物链。
“印度的监察机构应该立即组织毒理学调查，弄清楚转基因棉籽油中Bt毒素究竟在多大程度上污染了人类血液系统以及由此产生的长期影响。"
