Comments on GM Science Review Open Meeting - Science Museum 23rd January from Dr Erik Millstone, SPRU - Science and Technology Policy, University of Sussex.

During the course of the Open Meeting of the GM Science Review at the Science Museum on the evening of Thursday 23rd January a call was made for someone to provide a definition of the concept of 'substantial equivalence'. This message is intended to provide a response to that call, and is intended not just to extend the debate but to provide an input to the Review.

It would be unwise to try to provide one single definition of the concept of substantial equivalence because what has happened is that the meaning of the term has changed over time. A more appropriate question would therefore be to ask how the meaning of the term has been changing. Many of the changes in the way in which the term 'substantial equivalence' had been interpreted have been effectively documented by Les Levidow & Joseph Murphy.(Les Levidow and Joseph Murphy, 'The Decline of Substantial Equivalence: how civil society demoted a risky concept', Paper for conference at Institute of Development Studies, 12-13 December 2002, 'Science and citizenship in a global context: challenges from new technologies' available at www.ids.ac.uk/ids/env/biotechpaperrev1Peter1.pdf )

As Levidow and Murphy explain, the initial interpretation of the concept was that 'equivalence' between a GM food and its non-GM antecedents could be established solely by reference to the results of chemical analyses of the foods. Once such 'equivalence' has been ascribed, the regulatory risk assessment process was in effect at any end; any product deemed substantially equivalent was presumed to be as safe as its non-GM antecedents. As the Canadian Royal Society put it, 'substantial equivalence' was sometimes interpreted as if it provided a 'decision threshold'. (Canadian Royal Society, Elements of Precaution: Recommendations for the Regulation of Food Biotechnology in Canada, an Expert Panel Report on the Future of Food Biotechnology prepared by The Royal Society of Canada at the request of Health Canada, Canadian Food Inspection Agency and Environment Canada)

In response to challenges from members of the scientific community and civil society, who argued that toxicological and immunological potential can not be reliably predicted from the results of chemical analyses alone, regulatory authorities have progressively reinterpreted the concept, and now represent it no longer as an endpoint to a risk assessment but only as a starting point, as a way of starting to frame a question, not as the basis for the answer.

As Levidow and Murphy explain: "Originally the concept served to emphasize similarities with conventional foods, but now it is often cited to pursue a more rigorous search for differences and their safety consequences. It is being interpreted to develop and require more stringent tests for unintended effects, e.g. for toxicity and allergenicity." (Les Levidow and Joseph Murphy, 'The Decline of Substantial Equivalence: how civil society demoted a risky concept', p. 17 ) Levidow and Murphy also argue persuasively that, even though the meaning of the term has changed over time and across jurisdictions, some protagonists try to argue that its current interpretation was always implicit in its earlier usage.

The change in the official interpretation of the concept represents a step forward and it now seems extremely unlikely that any European regulatory authority would approve the introduction of GM food into the European market merely on the basis of data from chemical analysis. Risk assessors and policy-makers seem to have understood that the status quo ante was un-sustainable. Nonetheless, judgements by risk assessors on particular occasions about how much, or how few, data can be deemed sufficient to provide the requisite reassurance remain contestable and contested.

While some members of the scientific community, and members of some expert advisory committees, assume that they are equipped to make such judgements, those judgements are not purely scientific ones. This entails firstly that responsibility for deciding whether or not the concept of 'substantial equivalence' should be used, and if so how it should be interpreted, should lie with policy-makers and not with expert scientific advisors, and secondly that the issue of the use and interpretation of 'substantial equivalence' should be considered not just within the Science Review but also as part of the Public Debate.