4.6 Responses to the critique
A number of responses to the commentary were published in the letters pages ofNature, almost all of which objected to the article. For our purposes, a particularly interesting response came from Peter Kearns and Paul Mayers, two scientists associated with the OECD:
Substantial equivalence is not a substitute for a safety assessment. It is a guiding principle which is a useful tool for regulatory scientists engaged in safety assessments. It stresses that an assessment should show that a GM variety is as safe as its traditional counterparts. In this approach, differences may be identified for further scrutiny, which can involve nutritional, toxicological and immunological testing. The approach allows regulators to focus on the differences in a new variety and therefore on safety concerns of critical importance. Biochemical and toxicological tests are certainly not precluded.
Since the concept of substantial equivalence was first described, several new foods have been assessed and knowledge has accumulated on how to use the concept. In parallel, the OECD, its Governments and others have continued to review its adequacy in food safety assessment and to develop supporting tools. The OECD's task force on the safety of novel foods and feeds, in particular, continues to focus on the application of the concept. This includes work on assessment methodologies when substantial equivalence cannot be applied, as well as efforts to identify the critical nutrients and toxicants found in major crop plants, as a focus for the demonstration of substantial equivalence.
Having read this quote, re-read the original OECD definition of substantial equivalence (Section 3.2). Do you think Kearns and Mayers are making a fair point?
The original OECD definition was quite vague, so you could argue that Kearns and Mayers' more rigorous description of an evolving assessment that 'can involve nutritional, toxicological and immunological testing' is consistent with the original. However, it could be argued that their description does not describe actual practice up to that date (1999).
In some ways, Kearns and Mayers' letter gave an indication of the subsequent evolution of safety assessment. In Europe, there was a reluctance to draft further legislation that referred to substantial equivalence. However, whether the principle was mentioned or not, the central idea, that to assess safety of a novel crop some comparison with its traditional counterpart is necessary, has remained at the centre of risk assessment methodologies.