THE IMPACT OF TRANSGENIC FOOD CROPS AND THE ENVIRONMENT - SOME ISSUES FOR THE DEVELOPING WORLD
JR WITCOMBE and D HARRIS
Department for International Development, Plant Sciences Research Programme, Centre for Arid Zone Studies, University of Wales, Bangor, Gwynedd LL57 2UW, UK
In the industrialized world, where over-production of food is common, consumers can afford to pay more for organically produced food. Europeans perceive genetic modification as only the seventh most important risk to food safety , but there are campaigns against the use of genetically transformed crops (GTCs) on the basis of environmental concerns. However, GTCs offer benefits in the reduction in the use of pesticides, the second greatest concern on food safety. For example, in 1996 US cotton farmers sprayed 250,000 gallons less insecticide by using GTCs. In contrast, many of the claimed risks from using GTCs are so low that they cannot be quantified.
The industrialized world can probably afford to reject the benefits of GTCs, but it would be unfortunate if environmental concerns in Europe should significantly delay or prevent the uptake of biotechnology in developing countries. Although risk assessment for the uptake of GTCs has to be as rigorous as in industrialized countries, they must be weighed against the risks of not employing them. Failure to take up these technologies in developing countries can only increase the risk of failing to feed their ever-growing populations. For example, between 1995 and 2025 the world's population is predicted to increase by over 40%, and rice consumption will increase by 65% from 457 to 757 million t . In developing countries, the balance of environmental concerns shifts more heavily in favour of GTCs because pesticides are often used without appropriate regulation. Even when regulations are in place to address health and safety and pollution concerns, infrastructure for enforcement is lacking.
The potential environmental benefits of replacing nematicides by transgenic nematode-resistant bananas in the Windward Islands was studied. As is typical in the international banana industry, nematicides are extensively used to control root nematodes that, on average, cause 30% losses when affected plants topple over. One nematicide, DBCP, was withdrawn, despite low LD50 values, when it was found to be carcinogenic. Of the six remaining, four are organophosphates and two are carbamates, classes of chemicals about which there are well documented environmental concerns. The use of transgenes derived from plants offers an environmentally friendly approach to nematode control. For example, cystatins from rice grains that form part of the human diet, when expressed in the roots of transgenic rice plants significantly reduce nematode infestation (Atkinson et al., in preparation). It is calculated that incomplete resistance of transgenic banana to nematodes will still significantly reduce nematicide use by increasing the interval between chemical treatments. Hence, transgenics can be seen as a valuable component in integrated pest management.
Rice yellow mottle virus (RYMV) is an example of an important developing-country disease where farmers do not spray pesticides as there is no known control. However, the deployment of transgenics resistant to RYMV that have recently been produced at the Sainsbury Laboratory (Baulcombe and Pinto, in preparation) will have indirect environmental benefits. Reductions in crop losses that lead to increased production per unit area reduce the pressures on marginal land. The biotechnology to produce RYMV resistance operates at the level of RNA. No foreign proteins are expressed, thus eliminating any possible risks concerning food quality. A functioning regulatory framework is not yet in place in RYMV-affected countries. There is a risk that in the year 2000, while it is predicted that half of the crops in the USA will be transgenic, developing countries will hardly have benefited at all.
The US National Research Council has argued that biotechnology is at least as safe as traditional plant-breeding methods . The introduction of Oryza glaberrima genes into O. sativa by non-biotechnological means to produce weed-competitive upland rice varieties  is considered. The introduction of these new varieties into Asia might allow the transfer of genes from O. glaberrima into wild species of rice with which O. glaberrima could never normally cross. These risks are such that, if the transfer had been made by biotechnology, the benefits to developing countries of these new varieties would have been significantly delayed.