Genetically Engineered Foods: The Hazards are Inherent in the Technology

by Mae-Wan Ho

THE technology of genetic engineering is an unprecedented close alliance between science and industry. Unfortunately, it is the most reductionist science and multinational industry at its most aggressive and exploitative. It is bad science and big business working together for big profit, aided and abetted by some of our governments. They make products that nobody needs and certainly not everybody wants, but they are forcing on us anyway, by refusing to segregate and label the products.

They displace and marginalise alternative approaches that address social and environmental causes of malnutrition and ill-health, and the need for sustainable agriculture that could regenerate the environment, guarantee long-term food security and at the same time, conserve indigenous biodiversity. Worst of all, they are pushing a technology that is inadequately researched, and, according to existing knowledge, is inherently hazardous to health and biodiversity.

Speaking as a scientist who loves and believes in the right kind of science, I have to say that it is bad science that has let the world down and caused the major problems we now face.

Reductionist science has given us the unsustainable intensive agriculture of the Green Revolution, which has also contributed to the world ecological crisis. A yet more serious, immediate crisis is public health, which testifies to the failure of decades of reductionist medical practices. According to the 1996 WHO report, at least 30 new diseases have emerged over the past 20 years, while old infectious diseases are coming back worldwide. Almost every month we hear reports of fresh outbreaks: Streptococcus, meningitis, E. coli. Many of the pathogens are, moreover, resistant to multiple antibiotics. Genetic engineering biotechnology really does bring new dangers. New findings reported in the mainstream genetics journals over the past 3-4 years point to serious hazards inherent in genetic engineering biotechnology itself.

Geneticists have now linked the emergence of both pathogenic bacteria and antibiotic resistance to horizontal gene transfer. Horizontal gene transfer is the transfer of genes to unrelated species, by infection through viruses, through pieces of genetic material, DNA, taken up into the cell from the environment, or by unusual mating taking place between unrelated species. For example, horizontal gene transfer and subsequent genetic recombination have generated the bacterial strains responsible for the cholera outbreak in India in 1992, and the Streptococcus epidemic in Tayside in 1993.

The E. coli 157 strain involved in the recent outbreaks in Scotland is believed to have originated from horizontal gene transfer from the pathogen, Shigella. Many unrelated bacterial pathogens, causing diseases from bubonic plague to tree blight, are now found to share an entire set of genes for invading cells, which have almost certainly spread by horizontal gene transfer. Similarly, genes for antibiotic resistances have spread horizontally and recombined with one another to generate multiple antibiotic resistances throughout the bacterial populations. Antibiotic resistance genes spread readily from bacteria inhabiting the gut of farm animals to those in human beings. Multiple antibiotic resistant strains of pathogens are now endemic in many hospitals.

What is the connection between horizontal gene transfer and genetic engineering? Genetic engineering is itself a technology designed specifically to transfer genes horizontally between species that do not interbreed. It is designed to break down species barriers and, increasingly, to overcome the species' defence mechanisms which normally degrade or inactivate foreign genes. It does this by using modified versions of precisely those genetic parasites, or vectors, that cause diseases including cancers and spread virulence genes and antibiotic resistances. Thus the technology will greatly increase the frequency of horizontal transfer of those genes that spread virulence and antibiotic resistances. What is even more worrying is that geneticists have now found evidence that antibiotics increase the frequency of horizontal gene transfer 100-fold, possibly because the antibiotic acts like a sex hormone for the bacteria, enhancing mating and exchange of genes between unrelated species. Thus, multiple antibiotic resistance cannot be overcome simply by making new antibiotics. The continuing profligate use of antibiotics in intensive farming and in medicine, in combination with the new commercial-scale practice of genetic engineering, may already be the main contributing factors for the rapid spread of multiple antibiotic resistance among new and old pathogens in recent years.


That is not all. One by one, those assumptions on which geneticists and regulatory committees have based their assessment of genetically engineered products to be 'safe' have fallen by the wayside. But there is still no indication that the new findings are being taken on board. On the contrary, regulatory bodies have succumbed to pressure from the industry to relax the already inadequate regulations. Let me list a few more of the relevant findings in genetics.

We have been told that horizontal gene transfer is confined to bacteria. That is not so. It is now known to involve practically all species of animals, plants and fungi. It is possible for any gene in any species to spread to any other species, especially if the gene is carried on genetically engineered gene-transfer vectors. Transgenes and antibiotic resistance marker genes from transgenic plants have been shown to end up in soil fungi and bacteria. The microbial populations in the environment serve as the gene-transfer highway and reservoir, supporting the replication of the genes and allowing them to spread and recombine with other genes to generate new pathogens.

We have been assured that 'crippled' laboratory strains of bacteria and viruses do not survive when released into the environment. That is not true. There is now abundant evidence that they can either survive quite well and multiply, or they can go dormant and reappear after having acquired genes from other bacteria to enable them to multiply. Bacteria cooperate much more than they compete. They share their most valuable assets for survival.

We have been told that DNA is easily broken down in the environment. Not so. DNA can remain in the environment where they can be picked up by bacteria and incorporated into their genome. DNA is, in fact, one of the toughest molecules. Biochemists jumped with joy when they didn't have to work with proteins anymore, which lose their activity very readily. By contrast, DNA survives rigorous boiling, so when they approve processed food on grounds that they do not contain DNA, ask exactly how the processing is done, and whether the appropriate tests for the presence of DNA have been carried out.

We are told that DNA is easily digested by enzymes in our gut. Not true. The DNA of a virus has been found to survive passage through the gut of mice. Furthermore, the DNA readily finds its way into the blood stream, and into all kinds of cells in the body. Once inside the cell, the DNA can insert itself into the cell's genome, and create all kinds of genetic disturbances, including cancer.

In summary, genetic engineering biotechnology is bad science and big business working together against public interest. It will exacerbate the very problems it proposes to solve. It gives rise to unethical, exploitative practices. In addition, it poses unique dangers to human and animal health and to the ecological environment. Members of the public are already being used, against their will, as guinea pigs for genetically engineered products. It is time a moratorium is imposed on releases and marketing of genetically engineered products, as is already the case in Austria. Furthermore, an independent public enquiry should be set up to assess the hazards and risks of genetic engineering, which takes into proper account the most comprehensive body of scientific findings.

(Mae-Wan Ho is a scientist at the Biology Department, Open University, U.K. The above is based on a speech delivered during the Head-to-Head Debate at the Oxford Centre for the Environment, Ethics and Society on 20 February, 1997.)

(New York 23-27 June 1997)