Risks of genetic engineering

By Debashis Banerji

THERE IS an air of great expectation, almost euphoria, about the potential role of genetic engineering in transforming Indian agriculture. In such an atmosphere it is easy to overlook the extremely disturbing questions being thrown up by rigorous scientific research about the very cornerstone of this approach - recombinant DNA (r-DNA) technology. There is mounting evidence being reported in authoritative scientific journals that this technology could have unpredictable, unprecedented, irreversible and disastrous consequences for the health of all living beings on earth. No wonder informed public opinion all over the world, especially in Europe, is asking for much greater public scrutiny of this technology, before it is approved for commercial production. Even the U.S.-based Union of Concerned Scientists, with 1,600 members, including 100 Nobel laureates, is raising serious questions about r-DNA. But debate in India has been limited. Is all the evidence even available to our farmers and consumers, to enable them to make an informed decision? Is the Government sufficiently seized of its role to protect the right to life of the Indian people that could be threatened by this technology?

As a plant physiologist, trained in molecular biology with over 40 years of research experience in the field, it is my considered view that r-DNA technology may eventually come to be regarded as one of the most dangerous technological interventions in the history of humankind. No one should be allowed to get away by saying that r-DNA is a mere carrying forward of nature's work or even of conventional breeding as practised thus far. r-DNA is a technology completely different from anything known so far. In nature, gene transfer is gradual, holistic and vertical, i.e., from parents to offspring. The same process is somewhat accelerated in conventional breeding. By contrast, r-DNA involves forced, uni-dimensional, horizontal gene transfer across species. Historically, progress in agriculture has entailed enriching crops in desired traits that can be inherited. Conventionally, this has been done by selection breeding or gene transfer via the hybridisation technique. Both these techniques are intra- specific, they operate within varieties of the same species. These techniques facilitate nature. In contrast, GE involves transfer of genes across species, genetic and even phyletic barriers. That is, transfers are made across different animals and plants, animals to plants, microbes to higher organisms etc.

In nature, DNA from a species cannot normally enter the cell of another species, survive in the new cell milieu or get incorporated in the latter's genome. This is due to barriers at the cell surface that preclude entry, as also the existence of enzymes that destroy the alien DNA. The exceptions to this rule in nature are the nucleic acids of infective bacteria and viruses that can enter all kinds of cells, survive there by using the cellular machinery and even get integrated into the host DNA. Genetic engineers have used precisely this phenomenon to carry out their horizontal gene transfers. They use the DNA of microbial pathogens/ parasites as ``carriers'' to smuggle an alien DNA fragment into plants. These are designed to deliver genes into cells and to overcome cellular mechanisms that destroy or inactivate foreign DNA. Being particularly good at transferring genes horizontally between unrelated species, they can jump out of the host into the other organisms, and will do so whether intended or not. Thus the very mechanism that has to be necessarily deployed to enable horizontal gene transfer becomes a potential source of proliferation of dangerous bacteria and viruses.

We must also recognise that a gene's expression is predictable, stable and reproducible only in its own evolved genomic environment, as is the case in nature and even conventional breeding. In r-DNA technology, however, the gene insertion is both random and in an alien neighbourhood, which produces a totally unpredictable disturbance in host genetic function as well as in that of the introduced gene.

What is more, to mark distinctly the cells where the transgene has been integrated, genetic engineers use ``markers''. These markers are usually antibiotic-resistant genes. This creates the danger of spread of antibiotic resistance in all organisms that come into contact with the transgene. Further to switch on the transgene, genetic engineers use ``promoters''. These promoters are DNA sequences, often derived from disease-causing viruses. A common example of this is 35SCaMV (from Cauliflower Mosaic Virus), which resembles the HIV and Hepatitis B viruses. Thus, each element of the r-DNA technology - carriers, markers and promoters - has potentially lethal consequences for the health of all living organisms. Scientific research journals have already brought out all these risks inherent to transgenic technology. A few of the many can be mentioned here.

The reputed journal Applied and Environmental Microbiogy reported a case where 25 per cent of the initial level of genetically engineered DNA survived for as long as one hour even after exposure to saliva, which is loaded with degradative enzymes. Not only that, it also integrated into the DNA of the bacterium Streptococcus gordoni, a major source of throat infections. By doing so, it transformed this susceptible bacterium into an antibiotic-resistant one. J. Davies in Science and D. Mackenzie in New Scientist have demonstrated the transfer of antibiotic- resistant genes from genetically-modified (GM) food residues into intestinal bacteria.

Chances of induction of cancer in mammalian cells by ingestion of foreign DNA (Tibtech, 1997) and residual GE Bovine Growth Hormone (BGH) in the milk of dairy cows (International Journal of Health Services, 1996) have been reported. According to the British National Institute of Health, the BGH is identical to human IGF- 1, the hormone that induces various kinds of cancers in humans at high levels of concentration. Further, K. Suzuki and others have reported in the Proceedings of the National Academy of Sciences, USA (1999) that consumption of GE foods could promote several auto-immune diseases, following the entry of undigested genetically engineered (GE) double-stranded DNA into the bloodstream.

Possibilities of creation of ``superweeds'' by transfer of herbicide resistance genes from transgenic crops have been reported both by J. Kling in Science (1996) and J. Bergelsen and his co-authors in Nature (1998).

The inherent risks of transgenic technology have already manifested themselves in a number of instances around the world. One of the first reported cases of disastrous unpredictable consequences of r-DNA technology was the death of 37 people and permanent disability of 1,500 others in the U.S. in 1989 after they consumed genetically engineered (GE) Tryptophan, a nutritional supplement. As P. Raphals explains in Science (1990), this batch of Tryptophan was produced by using genetically engineered bacillus amyloliqueformis as fermenter, which led to the unexpected appearance of several toxins in this batch.

Considering the mounting evidence of the very real dangers to human health posed by GE foods, one would have expected great vigilance to be shown by public regulatory authorities. However, the FAO-WHO's ``principle of substantial equivalence'', the basis for safety assessment, is a sad commentary on the lack of independence of international regulatory authorities. The principle means that any GE produce which is found to be ``substantially equivalent'' to its unmodified counterpart, would be regarded as safe and fit for human consumption. But unfortunately, while determining equivalence, or the lack of it, between GE and non-GE foods, only bulk, quantitative chemical analysis is carried out. No attempt is made to conduct qualitative, biochemical analysis or toxicity or allergenicity tests. Even compositional analyses are, for example, limited to uninformative amino-acid profiles. In the absence of rigorous testing, it will be impossible to recognise the huge dangers posed by recombinant-DNA technology. Alarmingly, the evidence I have presented in this article is only the tip of an iceberg that poses unprecedented threats of life on earth.

(The writer is Director, Baba Amte Centre for People's Empowerment, Madhya Pradesh, and formerly Professor and Head, Botany, CCS University, Meerut.)

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