GM food is safe to eat

Geoffrey Lean's article on the Pusztai affair (Special Supplement, 24 September) was unbalanced. No one forced Dr Pusztai to go on television and thus forgo the accepted scientific path of peer-reviewed publication. We all have to accept the consequences of the decisions we make in life, even though those consequences may turn out to be unpalatable.

There may have been only one peer-reviewed paper on GM food safety known to Dr Pusztai, but others using chemical analyses and feeding trials had been published in a steady stream from 1996 onwards - including at least eight papers from Monsanto scientists (see www. Present GM safety procedures are based on principles constructed after discussion with stakeholder groups by the World Health Organisation, the United Nation's Food and Agriculture Organisation and the Organisation for Economic Co-operation and Development. Substantial equivalence is not (and never has been) a rubber stamp for any GM food. It is simply a structured framework by which the safety of any novel food, including its novel constituents, can be questioned.

The most recent detailed study of GM food safety, from Professor Chen of Beijing, used GM sweet peppers and tomatoes. The examination of rodents involved detailed anatomical and histological analysis of all the main organs, detailed analyses of blood biochemistry, examination of numerous blood cell types and activity, sperm aberration tests, mutagen tests, animal feeding, consumption and weight-gain examination, and acute toxicity investigations. All were performed separately on both male and female rats. The results? No significant difference was detected in any of the rodent parameters measured above. Whatever Dr Pusztai felt he was observing has not been confirmed by other laboratories. Contrary to Lean's implications, a great deal is already understood about gene transfer between crops and wild relatives (where they exist), and has been for many years. The GM trials are designed to enable proper management decisions to be made concerning GM crop farming in the UK. GM food safety is already established.

Professor Anthony Trewavas FRS
University of Edinburgh