Thus far, in those countries where transgenic crops have been grown, there have been no verifiable reports of them causing any significant health or environmental harm. Monarch butterflies have not been exterminated. Pests have not developed resistance to Bt. Some evidence of HT weeds has emerged, but superweeds have not invaded agricultural or natural ecosystems. On the contrary, some important environmental and social benefits are emerging. Farmers are using less pesticide and are replacing toxic chemicals with less harmful ones. As a result, farm workers and water supplies are protected from poisons, and beneficial insects and birds are returning to farmers' fields.
Meanwhile, science is moving ahead rapidly. Some of the concerns associated with the first generation of transgenic crops have technical solutions. New techniques of genetic transformation are eliminating the antibiotic marker genes and promoter genes that are of concern to some. Varieties including two different Bt genes are reducing the likelihood that pest resistance will develop. Management strategies and genetic techniques are evolving to prevent gene flow.
However, the lack of observed negative effects so far does not mean they cannot occur, and scientists agree that our understanding of ecological and food safety processes is incomplete. Much remains unknown. Complete safety can never be assured, and regulatory systems and the people who manage them are not perfect. How should we proceed given the lack of scientific certainty? The GM Science Review Panel (p. 25) argues that:
‘There is a clear need for the science community to do more research in a number of areas, for companies to make good choices in terms of transgene design and plant hosts, and to develop products that meet wider societal wishes. Finally, the regulatory system … should continue to operate so that it is sensitive to the degree of risk and uncertainty, recognises the distinctive features of GM, divergent scientific perspectives and associated gaps in knowledge, as well as taking into account the conventional breeding context and baselines.’
The Nuffield Council (p. 44) recommends that “the same standards should be applied to the assessment of risks from GM and from non-GM plants and foods, and that the risks of inaction be given the same careful analysis as risks of action …” They further conclude (p. 45):
‘We do not take the view that there is enough evidence of actual or potential harm to justify a moratorium on either research, field trials, or the controlled release of GM crops into the environment at this stage. We therefore recommend that research into GM crops be sustained, governed by a reasonable application of the precautionary principle.’
FAO's Statement on biotechnology (FAO, 2000b) concurs:
‘FAO supports a science-based evaluation system that would objectively determine the benefits and risks of each individual GMO. This calls for a cautious case-by-case approach to address legitimate concerns for the biosafety of each product or process prior to its release. The possible effects on biodiversity, the environment and food safety need to be evaluated, and the extent to which the benefits of the product or process outweigh its risks assessed. The evaluation process should also take into consideration experience gained by national regulatory authorities in clearing such products. Careful monitoring of the post-release effects of these products and processes is also essential to ensure their continued safety to human beings, animals and the environment.’
Science cannot declare any technology completely risk free. Genetically engineered crops can reduce some environmental risks associated with conventional agriculture, but will also introduce new challenges that must be addressed. Society will have to decide when and where genetic engineering is safe enough.