The recent excitement over genetically modified foods

This essay was written by Derek Burke and was first published in the 1997 Mill Hill Essays.

Over the last year, genetically modified foods have been entering supermarkets in Britain as a result of the regulatory decisions made by the expert committee which I have chaired for the last nine years, the Advisory Committee on Novel Foods and Processes. The outcome has been mixed. Some have been accepted without hesitation by the public; vegetarian cheese and the paste made from genetically modified tomatoes come to mind. Others, notably the flour from genetically modified soya beans and an insect resistant corn have caused considerable controversy, and the consequences have reached right up to the top of decision making in the European Union and in some of its member states. Why is this, and what is the cause of the public’s concern? Let me try and explain what I think is happening, using as examples some of the modified foods that have come to the Committee for approval.

We used to think, we experts, that all we had to do was to decide whether a novel food or process was safe or not and a grateful public would accept what we said. We should have known better! Food irradiation, a process which I and many others believe to be safe, is unusable because of fears connected with the word irradiation, going back to the atomic bomb and fed by concerns about nuclear-power stations. That should have made us think again. When we started we had not grasped the very different ways consumers see risk. We learned our first lesson in late 1988, when we were asked to approve the use of a baker’s yeast genetically modified to increase the rate at which the bread rose. This seemed to us a good case with which to start. After all, the genetic change could have occurred by the normal yeast mating process. We could not see any problem, and in early 1990, a brief Press Release appeared which announced that “the product may be used safely”.

The press reactions were not enthusiastic, and varied from “Genetic yeast passed for use” in The Times, through “Man-made yeast raises temperature” in The Independent, to “Bionic bread sales wrapped in secrecy” in Today, and “Are the boffins taking the rise out of bread?” in The Star. The Consumers’ Association said “We think all genetically altered foods should be labelled”. The general reaction was so negative that the product has never been used.

About five years ago, we were asked whether meat from genetically modified sheep could enter the food chain. These sheep carried the human gene for a protein needed for the treatment of haemophiliacs. However, it often takes one hundred lambs to be reared before a single adult animal is produced which yields the protein in high quantities. We were asked about the animals which either contained no additional gene, or only an inactive gene or part of the gene. Could they be eaten? We could not think of any reason why animals without any foreign DNA should not be eaten. But were newspapers going to run the headline “Failures from genetic engineering in your supermarket”? What about the animals containing an inactive human gene? Was this just a stretch of DNA like any other? Or was it special, because it came from a human being? Would eating sheep meat containing a single human gene even be regarded as cannibalism by some? Would Muslims or Jews be concerned about pig’s genes in lamb, and vegetarians about animal genes in plants? A small Committee chaired by the Reverend John Polkinghorne investigated the concerns of a number of religious and interest groups. They found that Christians were divided. Some had no objections, but many had an uneasy concern, a feeling shared by others, which has been termed the “yuk” factor. The Jewish reaction was more straightforward, “If it looks like a sheep, then it is a sheep” was their comment. Muslims and Hindus were much more opposed, as were animal welfare groups and vegetarians. None of the groups were moved when we pointed out that there was effectively no chance of their eating the original human gene, for it was hugely diluted in the processes of genetic manipulation. But they were concerned even if the gene were completely synthetic. They were also concerned by the “slippery slope” argument. These sheep had only one human gene in one hundred thousand sheep genes. But what if it were half and half? Then all of us would be concerned. They were worried too about labelling, and wanted consumers to have choice. There was obviously quite widespread unease. The result was that not even the animals with no foreign genes will enter the food chain. Consumer concerns, even if they do not appear to have a rational basis to scientists, must be taken seriously and not brushed aside.

We have found that scientific and consumer issues are best settled side by side, not consecutively. The previous approach of “First sort out the science, and then look at the consumer issues” simply does not work. We learned this lesson first over the baker’s yeast, and then over the transgenic sheep, where we realised that the question was not going to be resolved by a purely scientific discussion. In the latter case we had to ask a series of scientific questions about the fate of extraneous DNA and the lower limits of detection of gene fragments that we would not have asked but for consumer concerns.

In plants, the first genes to be manipulated were those which protect the plants from the effects of herbicides. This is often put down to a plot by the manufacturing companies concerned to increase their sales of herbicides, and it is quite true that in discussions in which I was involved in the early 1980’s companies were aware of that opportunity. However the real reason they were selected was that the genes for herbicide resistance are single genes and therefore much easier to identify and manipulate than the multi-gene complexes responsible for other important features such as salt tolerance and drought resistance.

A number of products from several herbicide-resistant plants which are now being grown have been approved by the Committee. Many of these have been quite straightforward, but difficulty has arisen over a variety of soya beans which were made resistant to the herbicide glyphosphate. Glyphosphate works by inactivating a plant enzyme which is essential for the production of amino acids, the building blocks of proteins, and it thereby prevents plants from growing. Resistance was achieved by introducing into the soya beans a bacterial gene containing the genetic information for the production of a similar enzyme which is not affected by glyphosphate. The bacterial form of the enzyme, now made by the plant, remains active in the presence of glyphosphate when the plant’s own enzyme is inhibited. The Committee had no safety concerns over the product, which is the flour rather than the beans, since the DNA will be degraded during the production of the flour, and the bacterial enzyme, which is present at very low levels in the soya beans, less than one part in one thousand, did not present any food safety hazard.

The product did not need to be labelled, although information was provided by the retailer, as had been done in the successful launch of the paste from genetically modified tomatoes earlier in the year. However with soya, as you may know, the retailers have not been able to offer customers choice, because the genetically modified soya was mixed with normal soya at the source. Even if the crops could be harvested separately, there remain very substantial practical difficulties in keeping them separate through all the steps of processing and distribution. This would require either separate batch operations or duplicate plant and equipment at every one of these stages. However, this explanation of the difficulty over segregation has not been accepted by consumer groups, who have organised a series of demonstrations and boycotts. It is clear that consumers want to make their own, informed decisions and, following a Ministerial decision, food processors and retailers are now responding by much more extensive labelling. Meantime the Institute of Grocery Distribution is working on an agreement with American farmers’ organisations and distributors to ensure that genetically modified soya coming to Britain is separately packaged and labelled. It is extremely unfortunate that the way in which this product was introduced has set back the whole commercial development of plant genetic manipulation. Consumers do not see why they should lose their ability to choose whether or not to consume a product about which they may have concerns, simply to put money into the pockets of the farmers and the manufacturing companies.

More recently there has been concern about antibiotic resistance genes in genetically modified plants. Were such genes at all likely to be transferred to gut bacteria and, if so, did it matter? The Committee recommended approval of the modified tomato, despite it containing an antibiotic resistance gene, because the gene could only work in a plant and not in bacteria found in the gut. In contrast, a genetically engineered variety of maize contained, in addition to a bacterial gene that confers resistance to a corn boring insect and a gene that confers resistance to a herbicide, a third gene that confers resistance to the antibiotic ampicillin. This third gene was a source of trouble because it had the potential to be extremely active in gut bacteria if the gene were transferred accidentally. The antibiotic resistance gene served no useful function in the plant. It was simply a remnant left over from the genetic engineering process.

We asked ourselves whether there was any risk of transfer of this antibiotic resistance gene into gut bacteria when this maize was used for animal feed in an unprocessed form. The technical risk was certainly very small but the consequences of the transfer actually happening could be important. We did not recommend approval but this decision was overruled in Brussels. The European Union committees considered that the possibility that such a transfer might add significantly to antibiotic resistance in animals and man is remote. They did not consider, therefore, that the risk constituted a sufficient reason for a ban. However, this decision by Brussels has been challenged by several European Union countries, notably Austria, and the final outcome is still unknown. The consequences of these problems in food safety have been widespread. Mainly as a result of BSE, but also partly as a result of this difficulty, the Brussels food committees have recently been transferred to the Directorate for Consumer Affairs. In the United Kingdom the new Government is actively planning the formation of a Food Standards Agency, largely because of the loss of public confidence in the food approval process.

Why is this? Why do consumers want to make their own decisions? Basically I think because they have lost a lot of confidence in what they hear from politicians and to a lesser extent, from regulators. And what are the reasons for this loss of consumer confidence? Let me suggest several. First, scientists, and the expert approval processes, are no longer trusted as they once were. The man in the white laboratory coat no longer recommends washing powder, the consumer does. Some of this may be due to a general decline of deference, but there are other reasons. Scientists have sometimes been too influenced by commercial or political pressures, or just by fashion. Second, I think the public is largely unaware of the development of careful scientific methods of assessing risk that come much closer to objective evaluations. But it is also true that scientists find great difficulty in explaining what is meant by different degrees of risk. Our National Lottery, with its slogan of “It could be you” does not help either; the message is clear, even what is very unlikely may happen to you. It may well be that you are more likely to die while watching the National Lottery than win the jackpot, but that doesn’t stop people buying tickets. So the public perception is that even if the risk from a new product is very low, maybe it will happen to me! The difference is that it is an absolute certainty that someone will win the Lottery, if not this week then next. That certainty simply does not apply to biological risks. Third, the public finds it difficult to know how seriously to take the points put by the many single-issue pressure groups. Fourth, risks are assessed differently according to the context. We will accept quite high risks when we are seriously ill, but will not tolerate much risk at all with food. The practice of medicine is to restore natural function to an organism already threatened, but food is the ‘staff of life’, a basic good that must not be threatened.

One explanation for such conflicting views is that scientists and the public work from different value systems. Scientists and technologists are inclined to see novel applications of new discoveries as logical and reasonable, and to characterise opposition to them as unreasonable. “If only they understood what we are doing”, they say, “the public would agree with us”. Scientists are used to an uncertain world, where knowledge is always flawed. They can handle risk judgements more easily, and are impatient with those who differ from them. The public’s reaction is quite different. It can take the form of outrage. How dare the scientists do this without consulting us? Alternatively this kind of progress may be viewed with dread, in the same way that we would fear a nuclear power station explosion, or it can be tainted by stigma, the guilt by association with which some members of the public regard food irradiation. As a result scientists are sometimes regarded as arrogant, distant and uncaring. That is not a good image for science or for scientists.

There is another concern expressed by the public. Some think that scientists are playing God. The public asks “how do you know you are not going to release a new plague?”. Scientists reply that they see living systems as a unity, knowing that cells, from bacteria to man, work in much the same way. So of course it’s all right to move genes around – all we have to do is to explain it clearly and people will be reassured. We are not abusing our position as the most powerful species. We know what we are doing!

I think this is all too glib. There are first of all important technical issues to be talked about, particularly environmental issues. Will herbicide resistance spread to weeds, will antibiotic-resistance genes transfer from plants to man through gut bacteria? The environmental issues are being carefully regulated by the Advisory Committee on Release into the Environment that insists on a series of controlled trials, first in a contained greenhouse, then in a carefully isolated field plot, before finally going out to planting. The pollen dispersal and the adjacent flora are being monitored to see if there is any spread from the genetically manipulated crop. So far no problems have been encountered, but the situation needs to be carefully watched and concerns have been expressed that the case-by-case approach used by the Committee will not deal adequately with the sum of a series of decisions about release. It is therefore good news that an industry-wide code on genetically modified crop information has very recently been launched, which aims to ensure traceability and best practise in use by establishing a consistent approach to information-transfer for crops grown in the United Kingdom from initial stock to primary end product. Recently, too, the Nuffield Council on Bioethics has announced that it plans to undertake an enquiry into the concerns expressed about the genetic modification of plants and how those concerns might be met.

But there are other issues. There is the natural/unnatural issue. Some think that it is unwise, even unethical, to disturb the natural world and that genetic modification is unnatural because it crosses species barriers. Others believe that BSE resulted from the ‘unnatural’ feeding of an animal foodstuff to a herbivore; others still view BSE as a sort of Divine Judgement for upsetting the natural order of things. However, experience would suggest that not all that is natural is best. Fungal infection of crops with production of the ergot alkaloids is certainly not for the good of those who eat the crops. And why the yoghurt that I eat for my lunch is better for containing natural colouring defeats me!

But to go back to the beginning: why were the people we consulted so resistant to the idea of eating a human gene, even when it was totally synthetic? Partly, I think, because they do not draw the line between one gene and a thousand. Is this the start of a slippery slope? We must be able to draw a line somewhere, and I believe that we certainly have to try. We already do so in other cases, for example in the case of experiments on very early human embryos.

But I think there is another reason as well. I suspect that people think that there is something special about human genes. Is there a concern about what science is doing to our perception of humanness? People are loving, caring, choosing human beings, with deeply held beliefs and values, many of which are central to their view of what a human being is. They accept the centrality of our genes and they think that there must be something special about human genes, which must not be treated merely as chemicals. Is this a reaction to the idea that we are nothing but a bunch of genes? The concern of the public is not lessened by the aggressive determinism of some biologists, or the slant of some science-education initiatives. Calling man “the third chimpanzee” does not help. It is also a warning to all of us that in stressing the underlying simplicity and the order of the complex world which modern molecular biology reveals, and in stressing the power and effectiveness of modern technology, we must also stress its limits. Scientists, must be less assertive, less arrogant than is currently sometimes the case. Too often, driven by their attraction to new technology, they can be unaware of the possible dehumanising effects of their mechanistic interpretation of nature.

What lessons can we draw from this to guide us for the future? Let me suggest criteria for the development of new food products: the proposed manipulation must be technically possible, and now almost anything seems to be possible; it must offer an advantage to the consumer, not just to the producer; the regulatory process must be rigorous, open and universal; finally, the consumer must be offered choice, at least for some time.

Given these, I believe that biotechnology will dominate advances in the food and agricultural industries provided that the consumer understands and accepts the need for and the safety of the new products and processes. That is the challenge. Technical skills will not be sufficient on their own to turn this exciting and powerful new science into products and processes. However, the views and concerns of the public must be recognised and taken into account, and it is incumbent on scientists to continue to involve the public in scientific progress.


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