Jennifer Worth reports on a national conference
organised by the British Society for Allergy and Environmental and
Nutritional Medicine, on 5th November 1999, in London.
|Many people are concerned about the safety of Genetically
Modified foods, in spite of the repeated assurances of government regulatory
bodies in this country and in America that the risks are minimal to human
health. The lectures and discussions during the day showed clearly that
the public reactions are probably valid, and that official statements should
All the speakers of the day declared that they were fundamentally in favour of genetic engineering, as a scientific principle, but each of them said that we (the human race) are proceeding much too quickly, on the basis of too little knowledge, and that we should proceed with more caution. One speaker, (Dr. Antoniou), said that the more we find out about the DNA helix, the more complex and unknown it becomes. For example, twenty years ago, genes were considered to be isolated units. We now know that this is not so; genes exist in interdependent families, and can transfer within families and across groups. New facts are emerging all the time, and at a breathtaking rate.
Dr. Howard pointed out that risk assessments are fraught with hazards, because they are based on theoretical principles, not on scientific facts. They are therefore as much a matter of opinion as of science. The potential risks of GM foods cannot be assessed on our current understanding of genetic engineering because the variables are too great for any assessment to be regarded as valid. Data models cannot be fed the full facts because the science of genetic engineering is incomplete; a computerised assessment of risks will therefore be inaccurate. No insurance company will cover Monsanto or any of the international companies producing genetically modified seeds, because the risk assessment is unpredictable. Also, statements issued by the Royal Society should be treated with caution. The Royal Society, founded in 1660 for the promotion of scientific research, held as a basic principle that the Society would not meddle in politics, and would not give an opinion. After three hundred years, in 1960, both of these principles were removed from the constitution (at the time described by the Lancet as "an act of breathtaking impudence").
Dr. Goodwin analysed briefly the ecological complexities of the food web, which is in a perpetual state of exquisite equilibrium. Thousands of strands, or chains, are comprised in the food web of every species, and they are always changing. It exists in a continuous process of innovation and extinction, creation and destruction, upon which the quality of life depends. These changes are continuous and intrinsically unpredictable. However much scientific data we have, we will never be able to assess the full consequences of genetic engineering, because we will never be able to anticipate the shifting patterns. Viruses and microbes are at the basis of the food web, and these have the capacity for horizontal gene transfer, within families and across groups, which can re-combine, constructing a different mosaic of genes. The real danger of artificial gene transfer is that of unbalancing this complex food web. If the balance is tipped to a point where the food web cannot restabilise itself, the balance of creation and destruction will cause a genetic melt down of unpredictable consequences.
Dr. Lund, speaking on the ethics of the GM food debate, pointed out that the debate concerned not only human food, but the food of all animal life, and that we (the human race) can tip the balance at this point in time toward destruction on a massive scale. He spoke of the decline of Christian faith, and the "new religion" of science and technology. The high priests of science, (he said), are like men walking along a cliff edge in thick fog, and talking all the while amongst themselves, unaware of the fact that a 200 foot drop lies only inches away from their footsteps. Dr. Lund also spoke of the unacceptability of mutli-national companies controlling science and medicine. A new discipline is needed, combining science and ethics.
Dr. Michael Antoniou spoke of the lawsuit being brought by the Alliance for Bio-Integrity in collaboration with the Washington Centre for Food Safety against the Food and Drug Administration (FDA) in America. The plaintiffs claim that FDA policy is scientifically unsound and morally irresponsible. They claim that the FDA have repeatedly misrepresented facts presented by their own scientists over the safety of genetically modified foods released onto the American market. The FDA was required to present copies of their files to the plaintiffs' attorneys. These files, totalling 44,000 pages, are stimulating reading, (I am reliably informed), and, for those who have the stamina, copies are available from the Alliance for Bio-Integrity, Box 110, Iowa City 1A, 52244-0110, USA., fax 1515.472.6431.
The FDA openly admits, now, that it has been operating under a directive "to foster the US biotech industry", (though it does not say by whom the directive was issued). It has repeatedly declared that genetically modified foods are substantially the same as conventional foods, in flagrant disregard of warnings by their own scientists that genetic engineering differs from conventional practice, and entails a unique set of risks. Furthermore, the FDA files reveal violation of the US Food and Drug Act in allowing GM foods to be marketed without the required testing, on the premise that "they are generally recognised as safe".
Dr. Lund said that as a young research scientist he was once told "there are different degrees of truth", and that "science is pure; ethics leave a lot to be desired." He also said that, having regard to all the imponderables surrounding GM foods, the only way of testing their safety upon human health is for them to be consumed by human beings, to see what happens. But this is not ethical practice.
Dr. Pusztai and Dr. Ewan lectured separately at the BSAENM conference, but in this report their lectures are taken together. They worked together at the University of Aberdeen, and their joint paper is published in the Lancet, vol. 354, 16.10.99. (In the same edition the Lancet published a paper by Fenton et al. on the "Differential binding of the insecticidal lectin GNA to human blood cells." This paper considers that the evidence of snowdrop lectin binding to human white cells supports the need for greater understanding of the possible health consequences of incorporating plant lectins into the food chain.
The study at Aberdeen University was commissioned in recognition of the fact that whilst genetically modified plant products are entering the human food chain, few studies have been carried out on the possible effects of GM products on the mammalian gut mucosa. The study was supported by the Scottish Office: Agriculture, Environment, and Fishery Department (grant number FF 818).
GM potatoes grown at Rothamstead Experimental Station, Harpenden, Herts, were used. The snowdrop lectin galanthus nivalis agglutinin (GNA), containing the gene which increases insect resistance, was introduced into the potatoes (snowdrop bulbs and leaves are poisonous to humans). The potatoes were regarded as a successful line, due for general release to the public. They were described by Rothamstead as being "substantially equivalent to the parent, or non- GM potatoes." However, the potatoes were analysed before being fed to the rats, and substantial differences were identified . Changes in the level of protein, sugar and starches were found, and these changes were inconsistent in different batches. The lectin content was consistently twice as high as that of the natural potatoes, possibly caused by the introduction of the Snowdrop lectin (GNA) into the potato, (lectins are potentially inflammatory to the human gut).
Young male rats were selected for experiment and fed on a diet of raw and cooked potatoes for ten days. Comparisons were made between rats fed on:
1. GM potatoes
2. non-GM potatoes, with a supplement of GNA (the snowdrop lectin) given separately
3. non-GM potatoes, with no supplement
After ten days the rats were slaughtered and their intestinal tracts examined. The presence of the snowdrop lectin (GNA) in the diet was associated with significant intestinal changes, compared with the rats fed on non-GM potatoes. The rats fed on raw potatoes were more affected than those receiving cooked potatoes.
When the study showed differences in rats fed on GM potatoes, the contract was abruptly terminated.
Each of the separate parts of the rats' intestinal tracts were examined in detail: The stomach, jejunum, ileum, caecum, colon. It was beyond the scope of the two lectures to analyse in detail the physiological changes observed, but slides were shown, illustrating abnormalities in the rats fed on GM potatoes, namely:
1. thickening of the stomach mucosa
2. hyperplasia of cells in the jejunum
3. lengthening of the jejunal crypts
4. lymphocytic infiltration in the jejunal epithelium
5. mucosal binding randomly dispersed throughout the gut
6. depleted caecal mucosal thickness
7. colonic enlargement
Changes in other organs were observed: the pancreas and spleen of some rats appeared to be highly stimulated; the liver of some rats was diminished; the testes of some rats were affected. The heart and brain were not examined because the experiment was halted before examination could take place. Only male rates were used in this experiment, and Dr. Pusztai said that the changes noted in the testes might apply also to the ovaries of female rats, but as there have been no equivalent experiments carried out on female rats, it is impossible to assess how the female reproductive system would react to a diet of GM potatoes.
During the ten days of experiment all the rats appeared to be perfectly healthy and increased in body weight normally. Therefore, whilst physiological changes of the gut were noted, it is not known whether these changes would or would not have significance for the future good health of the animal. To the knowledge of Dr. Pusztai and Dr. Ewen, no future experiments are planned to assess the long-term effects.
Dr. Pusztai said: "experiments raise the possibility of a plant vector in common use in some GM plants affecting the mucosa of the gastro-intestinal tract and exerting powerful biological effects, and this may also apply to other GM plants containing similar constructs, particularly those containing lectins, or any plant expressing lectin genes or transgenes."
Dr. Pusztai ended his lecture with the words: "it is impossible to predict what will happen to all forms of life on this planet if experiments in genetic engineering continue unchecked."
Towards the end of the day, general discussion focused on medical concern about the unpredictability of GM foods upon human health, for the following reasons:
1. The insertion of foreign genes into any organism is not precise. Vast numbers of DNA are inserted at random, and their "desirable" characteristics looked for. However, there may be "undesirable" characteristics present, which are not looked for, and which remain unknown, and therefore the effects upon human health will be completely unknown.
2. To ascertain what has gone where in the random insertion, "marker genes" are used, for antibiotic resistance. Early work from Holland suggests that these genes could transfer horizontally into normal gut bacteria, thus breeding antibiotic resistant bacteria in the human gut. This could increase the incidence of gut disbiosis, a problem already associated with many diseases.
3. A "carrier" is needed to move DNA from one species to another. The carriers are usually viruses, and the most commonly used is the cauliflower mosaic virus, because of its invasive properties. No-one has made an assessment of the problems that might arise from introducing invasive viruses into the human genome.
These are just three of the known problems that doctors recognise could arise from the widespread consumption of GM foods. The number of unknown problems is unpredictable.
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