Champions of genetically modified (GM) crops say they are safe to eat, good for the environment and may provide cheaper and better food. Detractors claim that GM crops are unnatural, dangerous and unnecessary.

The war of words rages on a number of fronts - scientific, political and economic, pitting nation against nation and producer versus consumer. While recent scientific evidence allows that GM crops are, at least, as safe to grow and consume as conventional crops, much still needs to be done to convince consumers that GM crops are harmless to them and the environment, and that the benefits of such crops will outweigh the potential costs.

Sowing the seeds of discontent

The main battle lines have been drawn between the world's main producers (America, Argentina, Canada) and the European Union, among others, with the conflict looking likely to escalate in to a fully fledged trade war at the World Trade Organisation.

At present, the EU has a five-year de facto moratorium on new GM varieties, and this is causing concern among the pro lobby as it sees its commercial interests in biotechnology being adversely affected by what is seen as European farm and political interests.

The main GM crops are commercially grown in 16 countries, tested in several more and associated commodities are widely traded, even in the EU. The three crops making up 95% of the land under GM cultivation are: soybean (62%), maize (21%) and cotton (12%). When GM crops first appeared, the fuss kicked up by green lobbyists and organic farmers, and the media frenzy about "Frankenfoods", resulted in the foodstuffs being withdrawn from supermarket shelves and the present European moratorium.

Frankenscience?

GM crops are continuously screened for nutritional content, toxicity, allergenicity and genetic stability, and current evidence concludes that they are as safe to eat as conventional foods, and are no worse for the environment than conventional farming.

There are two broad types of genetic modification accounting for almost 99% of the 59m hectares of GM crops in commercial cultivation (less than 5% of world farm acreage, 2002 figures).

One type, Bt, takes a gene from a bacterium and puts it in to plants to give them resistance to certain insects without the use of chemical pesticides. The other uses bacterial genes to give plants resistance to particular herbicides, such as glyphosate.

Herbicide-resistant crops are not much more productive than the non-GM varieties, but do provide a number of benefits to the producer; they are easier to manage, demand less weeding and require lower-cost, less toxic herbicides. Bt crops, on the other hand, can produce higher yields under certain circumstances. They also need less insecticide.

The three key issues under discussion, and the current state of knowledge, are:

1. Is eating GM crops dangerous? While such foods on the market are unlikely to be toxic, they are likely to be just as nutritious and carcinogenic as conventional food. Horizontal gene transfer of modified DNA to bacteria in our guts is unlikely to happen and no definitive proof of such a process yet exists. No long-term clinical trials have yet taken place and there is little understanding of the potential allergies that might be caused by consuming GM crops (the same holds true for our understanding of which proteins in ordinary crops trigger allergies). However, for up to seven years, millions of people have been eating food derived from animals fed on GM diets and no substantial ill-effects have been reported.

2. Will GM crops affect the environment? Herbicide-resistant crops are as invasive and persistent as ordinary crops, and some are toxic to animals other than the targeted pests. This toxicity could work its way up the food chain. Insects evolve to overcome conventional pesticides, and it is expected that they will likewise evolve to become resistant to pest-resistant genes. Farm-scale trails are underway to determine whether GM crops affect farm biodiversity, and the effect on soil ecology is also being studied.

3. Can genes from GM crops flow into other plants, microbes or viruses? There is evidence in Canada and elsewhere of genetic contamination of traditional and organic crops by GM varieties. In addition, it is theoretically possible for GM-plant DNA to remain in soil for months, possibly to be taken up by microbes.

As far as the consumer is concerned, GM crops have made little difference to the quality and cost of supermarket goods. The Americans are generally unperturbed by GM crops or foodstuffs. In Europe, consumers show "cautious uncertainty", stemming from the apparent lack of benefits afforded by such crops. We have been promised healthier, better-tasting foods, such as heart-friendly tomatoes high in anti-oxidants, but scepticism remains high.

Farmers generally see cost advantages from GM crops, mainly through reduced pesticide use, and most of the six million or so who have taken the plunge appear to like them. Despite the seeds being costlier, acreage dedicated to GM crops continues to increase. There is a concern that such farmers are becoming beholden to producers, locked into complex and stifling contracts. Also, the GM crops currently available may be of little relevance to poor farmers in the developing world who require improvements in staple crops. These may be better served by improved farm management than by GM.

Brave new world

George Bush claims that Europe's unwarranted fears of GM crops are hurting American and African farmers both, the latter through possible reluctance to take full advantage of the technology for fear of losing access to European markets. Europeans argue that many poor countries share their own reservations.

Millions of farmers in developing countries are growing GM crops, mainly cotton, with impressive economic gains due to decreasing pesticide usage. Scientific research evidences no proof that GM crops now in cultivation are more dangerous to human health than conventional crops. The picture remains murky, with argument and counter-argument obscuring facts and legitimate debate.

Recently, the UK government launched a massive national consultation involving over 675 public meetings and eliciting over 36,000 written responses, and the result was overwhelmingly against producing and consuming GM crops.

Although the Agricultural Biotechnology Council (umbrella organisation for GM companies in Britain) claimed that 80% of the response forms were orchestrated by anti-GM campaign groups, the results are regarded as reflecting public opinion. In addition, the government's own civil service concluded that they were unable to find any compelling economic reason for introducing GM technology. The British public, it appears, remains overwhelmingly hostile, distrusting those responsible for pushing it forward, namely government and multinational biotechnology companies.

If nothing else, one positive outcome from the whole debate has been the shake up of food regulation, farm testing, commodity handling and public consultation, hauling the process in to the 21st century as, The Economist is wont to put it (July 26). From a scientific point of view, the debate has highlighted major gaps in the understanding of GM technology, as well as conventional crop technology. There is no doubt that there is a case for solid scientific research into the long and short term benefits, or otherwise, and as we all know, uncertainty drives good science.

For further information on the UK GM-debate, log on to www.gmsciencedebate.org.uk. Also of interest is the special report "Genetically Modified Food" in The Economist of July 26.

Dr John Attard, Ph.D., MBA, is the managing director of Rescitech Ltd, a technology commercialisation and R&D management consultancy based in Cambridge, England. He can be reached on john@rescitech.co.uk