Leading Article: Scientists sow the seeds of doubt over GM crops

AT THE height of pre-election fever, Labour's media maestro Peter Mandelson shouted across the campaign war room: "Get me a bishop!" He urgently needed an independent moral authority to condemn the Conservative portrayal of the then leader of the opposition, Tony Blair, as having "demon eyes". The Bishop of Oxford, Richard Harries, obliged by issuing a statement deploring the use of satanic imagery in political advertising.

The same level of professionalism is now being applied to the rather more serious business of Government policy in relation to genetic engineering. A leaked memo from a meeting of ministers last week revealed their anxiety to find an "independent" scientist who could appear on the Today programme to support the Government line.

But Jack Cunningham's spin strategy has been knocked off course by the disclosure in this newspaper yesterday that the independent scientist whose job it is to advise the Government agrees with its critics. Sir Robert May, the Government's Chief Scientific Adviser, told the Royal Society for the Protection of Birds that genetically modified (GM) crops should not be approved for commercial use until at least 2003.

In fact, Sir Robert's comments (despite his panicky attempts to back- pedal yesterday) illustrate the dangers to the Government of attempting to conduct an important scientific debate as if it were an election campaign. Sir Robert's letter suggested that the common ground between the Government and the environmentalists is greater than the impression given by both sides. Amid the confusion of a consumer scare over genetically modified food, "green" lobbies have called for a moratorium on the licensing of GM crops. The Prime Minister has refused, insisting that decisions about whether crops can be grown commercially should be "based on science". He is right to do so: an arbitrary time limit on the approval of GM crops cannot be justified - crops should be approved when the balance of scientific opinion is that they are safe. But there is no prospect of this being established satisfactorily before the end of the first set of trials in the UK in four years' time.

Let us emphasise again the difference between GM food and GM crops. The evidence is that GM soya and tomatoes are safe to eat. There must be some small risk of unknowable effects, which is why GM food should be labelled as such and the consumer allowed to choose. The risk of growing GM crops is quite different, and has no direct impact on human health. The threat is to the fragile balance of ecosystems in the countryside. Soya farmers in America are able to use more toxic chemicals on their land because crops have been designed to be resistant to weed-killers and pesticides. This was not the brave new world once sold by the glamorous pioneers of the biotechnology industry; they promised new plants that would be designed to be resistant to pests, and would therefore mean that farmers could use fewer chemicals. But even this greener and more benign use of genetic technology has its costs: "pests", too, are a valuable part of the ecosystem. Yesterday, we reported that GM maize in America, genetically engineered to produce a natural toxin to protect it from insects, poses a threat to the monarch butterfly. In that sense, we do not need the controlled trials in this country; what is happening in America is a giant experiment in the effects of GM crops on the environment.

Biotechnology holds out the prospect of huge benefits to humankind, especially in the field of medicine, but the doubts are growing about using it simply to intensify industrialised agriculture still further. The Government should recognise that a policy that is genuinely "based on science" would be cautious about licensing any GM crops for many years yet.