Handling the genetic hot potatoes

Are genetically modified foods safe? Derek Burke, a former regulator, discusses the evidence and the risks

Genetically modified foods have been entering British supermarkets over the past year. The outcome has been mixed; some have been accepted without hesitation by the public - for example, vegetarian cheese and the paste made from genetically modified tomatoes. But others, notably the flour from genetically modified soya beans, have caused controversy. Why? After all, products such as insulin, interferon and growth hormone - all made in bacteria or animal cells by genetic modification - have been accepted by consumers. If it is OK to use genetic modification for medicine, then why not to produce more food?

Just this week we heard about experiments at the Rowett Research Institute in Scotland, on what happened when genetically modified potatoes were fed to rats. The potatoes carried lectin genes and the diet affected the animals' immune system. Some will think that this is because all genetically modified products are really toxic, and this is just the first example of toxicity that we have picked up. Others will say that it was not a particularly surprising result because lectins are known to bind to other proteins and the complex immune system involves many proteins.

This is exactly what the regulatory system is for - to pick up new problems when they arise. The United Kingdom's regulatory system is the world's toughest and most open; these potatoes would not have got through it. There is no question of these potatoes appearing on supermarket shelves. But the result will worry some.

Indeed, whether we want to use genetic modification at all to produce more food is disputed. Critics argue that the planet's food problems are due to economic and political problems, not because we cannot grow enough. There is truth in that. If the world's food supply had been evenly distributed in 1994, it would have provided an adequate diet of about 2,350 calories per day for 6.4 billion people, more than the world population. Yet it still seems perverse to me to walk away from a potential increase in the world's food.

The first two genetically modified products - tomato paste and vegetarian cheese - offered the consumer financial savings and choice. Safeway sells 170g of the modified tomato paste at the same price as 142g of the conventional product. By contrast, the flour from the herbicide-resistant soya from the United States chemical and biotechnology company Monsanto offers no obvious advantage to the consumer, only to the producer. The flour is not labelled as genetically modified and therefore consumers feel they are not being given an informed choice.

Monsanto's soya was modified by the introduction of a gene from a soil bacterium to make the plant resistant to the weedkiller glyphosate. This means that the weedkiller can be used - just once - to spray the soya crop after the plant is above ground. This replaces the previous practice of spraying before emergence and again after emergence with a second, more selective, herbicide.

Monsanto argues that a smaller amount of a safer herbicide is used and no one has refuted this. The soya has real advantages too for the farmer. It accounted for only 2 per cent of the crop in 1996, but was up to 15 per cent in 1997 and is predicted to be 40 per cent in 1998. I believe that this new crop is here to stay. Others are in field trials in the US, including crops such as disease-resistant rice, which is important for the developing world.

Most retailers have not been able to offer their customers choice between a modified and an unmodified soya product because conventional and modified soya are grown side by side in the United States and are not separated. North American farmers are unwilling to do so because the costs of segregation would be high. The US government has supported the farmers by stating that any attempt to ban the import of soya would be considered a breach of World Trade Organisation agreements as such products can be excluded only if they are unsafe.

How do we know genetically modified soya is safe? It is tested extensively by the company, which has a reputation to protect. Then, before it can be used in Britain, it needs government approval. Ministers take the advice of the Advisory Committee on Novel Foods and Processes, which I chaired for nine years. This expert committee, which includes a consumer representative and an ethical adviser, considered this product to be as safe as conventional soya, and so advised the minister.

The public has been equally concerned about the effect on the environment. Will these crops lead to an increase in the use of herbicides? Will the modified genes escape from the environment to fill our fields with resistant rape, or will the genes spread to other species? There is no more reason to think that a gene from a soil bacterium will escape than one of the 100,000 plant genes. There are rarely new problems.

But if it is as safe as unmodified soya, and we can control any adverse effects on the environment, why has there been so much consumer concern? There are several reasons; scientists, and the expert approval processes, are no longer trusted as they once were. I think the public is largely unaware of the development of careful scientific methods of assessing risk, such as the use of hazard analysis, to come much closer to an "objective" evaluation of risk.

But it is also true that we scientists find great difficulty in explaining, and the public in understanding, what is meant by different degrees of risk, especially for very low risk. The public finds it difficult to know how seriously to take the points put by the many single-issue pressure groups, and 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. BSE has affected us all.

One explanation for such conflicting views is that scientists and the public work from different value systems. Scientists and technologists see novel applications of new discoveries as logical and reasonable and characterise all opposition as unreasonable. Scientists are used to an uncertain world, where knowledge is always flawed, they can handle risk judgements more easily and, I am afraid, are impatient of those who differ from them. The public's reaction is quite different.

Other issues surface too; hostility to high-intensity agriculture, and particularly concern about the way in which the agrifood business has consolidated into about six companies worldwide. Decisions about the future of our food are being taken in the US or in Switzerland. Consumers feel they have lost control and blame the technology. Genetically modified foods seem to have become a lightning rod for many modern concerns.

So what are we to do? First, explain as carefully as possible what is happening and why. Second, open up the regulatory process; nothing must be hidden. Third, if possible, offer choice between the traditional and the novel product, at least for some years. Fourth, label these new foods as helpfully as possible. Fifth, monitor to make sure that if there are unexpected problems, we pick them up quickly.

Derek Burke was chairman of the Advisory Committee on Novel Foods and Processes, 1989-1997.