The intersection between science and value judgements comes quite clearly in the topic introduction and must be a theme that the Science Review reflects upon - who decides what is environmental harm and why? In this topic, GeneWatch believes the Review process should take a comparative approach - not trying to determine whether GM crops will be good/bad for the environment, but to look at a range of options. It setting the criteria for the evaluation, there should be a widespread consultation with stakeholders and the public. Such an approach might intersect and inform the economics strand better where comparative evaluation has to be undertaken. In preparation for the debate about the outcomes of the farm-scale evaluations, the review should consider the extent to which reliable extrapolations in scale and time can be made.

Therefore, additional questions that need to be addressed include:

• To what extent can the farm-scale evaluations be relied upon to detect ecological impacts of growing herbicide tolerant crops? Over what period do ecologically significant changes take place and how likely are these to have been detected by the FSEs? Considering these questions do not require completion of the FSEs.
• What gaps are there in our knowledge about ecosystem functioning and how do these affect prediction?
• What are the comparative environmental impacts of organic, integrated pest management, conventional and GM herbicide tolerant systems? What are the uncertainties and how could these be resolved?
• How reliable have farming guidelines and regulations been in the past in mitigating against the adverse impacts of agricultural practices on the environment? What lessons can be learnt for the management of GM crops?

Much research had shown that it is farmer behaviour that is the most sensitive factor in determining the emergence of volunteer weeds and potential environmental impact. Human behaviour must, therefore, be an important factor in the science review of environmental and other impacts. What information is available from practices in those countries where GM crops have been commercialised? Are separation distances being observed, have refuges to prevent the emergence of Bt resistance been followed? These questions have important consequences for the medium to long-term environmental impacts. If Bt resistance emerges, for example, the loss of effectiveness of Bt sprays could lead to the increased use of more harmful sprays.

• Would a slow, staged introduction of GM crops allow their impacts to be evaluated more accurately and any adverse impacts to be identified and remedied more easily than leaving things to market forces? Taking into account the uncertainties, would a managed system be a more scientific approach?

Literature that should form part of the evaluation:

• Squire, G.R. et al (1997) A model for the impact of herbicide tolerance on the performance of oilseed rape as a volunteer weed. Annals of Applied Biology 131: 315-338.
• Watkinson, A.R. et al (2000) Predictions of biodiversity response to genetically modified herbicide-tolerant crops. Science 289: 1554-1557.
• Wolfenbarger, L.L. & Phifer, P.R. (2000) The ecological risks and benefits of genetically engineered plants. Science 290: 2088-2093.
• Parker, I.M. & Kareiva, P. (1996) Assessing the risks of invasion for genetically engineered plants: acceptable evidence and reasonable doubt. Biological Conservation 78: 193-293.

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