Two U.N. Food and Agriculture Organization economists, Terri Raney and Prabhu Pingali write a sharp article in the September issue of Scientific American (sub required) on how genetically enhanced crops can and do help poor farmers in developing countries. I can't quote everything, but one particularly good point the FAO economists make is that scientific evidence shows that currently available biotech crops are not harming either people or the natural environment. To wit:
The chief food-safety concerns are are fears that allergens or toxins may be present and that other unintentional changes in the food composition may occur. Yet to date no verifiable toxic or nutritionally deleterious effects resulting from the consumption of transgenic foods have been discovered anywhere in the world (emphasis mine). National food safety authorities of several countries have evaluated the transgenic crops currently being grown commercially and the foods derived from them, using procedures based on internationally agreed upon principles, and have judged them all safe to eat.
Environmental concerns center on the spread of transgenes to related crops or weeds ("gene flow"), the development of herbicide-resistant weeds, the development of insect pests resistant to the Bt toxin (which has long been used as a pesticide, particularly by organic farmers), harm by insect-resistant crops to nontarget organisms, and indirect environmental effects that come about because transgenic crops lead to different cropping practices.
Scientists disagree about the likelihood and potential consequences of these hazards. Gene flow, for example, is acknowledged to be possible when transgenic crops are grown close to related plants, but the transgene will persist and spread only if they give the recipient plant a competitive advantage. Such gene flow could inflict economic harm by, for instance, making a product ineligible for a status such as "organic." What would suffice to constitute ecological harm is more controversial.
Thus far, none of the major environmental hazards potentially associated with transgenic crops has developed in commercial fields. Herbicide-resistant weeds have been observed–although not necessarily caused by growing transgenic crops–and so far they can be managed by alternative herbicides. The lack of negative impacts so far does not mean they cannot occur, of course. Scientific understanding of ecological and food-safety processes is incomplete, but many of the risks highlighted for transgenics are similar to risks inherent in conventional agriculture as well.
Raney elsewhere argues that biotech crops can be pro-poor.
The economic evidence available to date does not support rhe widely held perception that transgenic crops benefit only large farms; on the contrary, the technology may be pro-poor. Nor does the available evidence support the fear that multinational biotechnology firms are capturing all of the economic value created by transgenic crops. On the contrary, the benefits are shared by consumers, technology suppliers and adopting farmers, although non-adopting farmers are penalized as their competitors achieve efficiency gains they are denied.
Her whole article on the pro-poor potential of biotech crops here.
With regard to gene flow, researchers have long recognized that the issue is not confined to genetically enhanced crops; it occurs between conventional crops and other plants as well. For more on gene flow see my column "Transgenics Gone Wild!"
For another report on the pro-poor nature of genetically enhanced crops take a look at this 2006 one by the Union of German Academies of Sciences and Humanities.