The phrase substantial equivalence is given to a method used in the regulation of genetically modified foods (hereafter GM foods). In the beginning, the method meant that if a novel food could be classified as being "substantially equivalent" to its traditional counterpart then it could be treated with the same respects in regards to safety. Over the history of its usage, the precise definition and implementation of "substantial equivalence" has been contested. As a consequence the meaning and use of the method has changed over time. In the early-to mid 1990s, with the construction and dissemination of GM food becoming an imminent possibility, national and international authorities began to consider a suitable regulatory framework for the emergent technologies. However, existing regulatory frameworks did not cover GM food. In an article printed in the scientific journal Nature, Erik Millstone and his colleagues (1999) state that:

"^*he biotechnology companies wanted government regulators to help persuade consumers that their products were safe, yet they also wanted the regulatory hurdles to be set as low as possible. Governments wanted an approach to the regulation of GM foods that could be agreed internationally, and that would not inhibit the development of their domestic biotechnology companies".

After some debate, the notion of "substantial equivalence" was first articulated by the Organisation for Economic Cooperation and Development (hereafter OECD), which hosted discussions that led to a key publication 'Safety Evaluation of Foods Derived by Modern Biotechnology' (OECD, 1993). This document promoted "the principle of substantial equivalence" as a guide to the risk assessment of GM foods:

"The main conclusion of this report is as follows: if a new food or food component is found to be substantially equivalent to an existing food or food component, it can be treated in the same manner with respect to safety. No additional safety concerns would be expected. Where substantial equivalence is more difficult to establish because the food or food component is either less well-known or totally new, then the identified differences, or the new characteristics, should be the focus of further safety considerations". (OECD, 1993: 13)

Thus, in the beginning, legislators treated GM foods by analogy with their nearest existing known counterparts. If a GM food was found to be "substantially equivalent" to its nearest existing counterpart, then it could be treated with the same respects in terms of safety, and no additional risk assessments were necessary. A biotechnology company could establish "substantial equivalence" by comparing attributes such as protein, carbohydrate, fatty acid levels between the novel food and its traditional counterpart, however there were no clear and universal guidelines stipulating what to test and how similar the items in question should be. Erik Millstone et al state:

"The concept of substantial equivalence has never been properly defined; the degree of difference between a natural food and its GM alternative before its 'substance' ceases to be acceptably 'equivalent' is not defined anywhere, nor has an exact definition been agreed by legislators. It is exactly this vagueness which makes the concept useful to industry but unacceptable to the consumer".

Thus, substantial equivalence proved to be immensely controversial. Consumer organisations, environmental groups and a few leading scientists criticised the concept for helping to play down the novelty of genetic engineering and facilitating its commercialisation. It was said that the amount of comparative data required to establish "substantial equivalence" involved "a somewhat subjective judgement" (Royal Society 2002: 5-6).

In response to these concerns, substantial equivalence has been redefined and demoted in the regulatory framework - albeit implicitly - because classifying a GM food as being "substantially equivalent" no longer justifies a lack of safety assessments, as was initially suggested by the OECD document of 1993. The current consensus is that substantial equivalence should be considered as being a starting point, and not an end point, in the regulation of GM foods. This much was made clear in 2002 when the British government's leading scientific advisory body, the Royal Society, stated that "^*ubstantial equivalence is a very blunt instrument. It is a flawed concept if used on its own" (Royal Society, 2002). Regulators are now placing much more emphasis on identifying the unintended consequences of genetic modification. Moves are being made to develop better methods for testing composition, metabolic activity, toxicity, allergenicity, etc. Presently, the consensus is that "substantial equivalence" should only be used to guide or inform safety assessments.

See also

• risk management
• genetically modified food

Bibliography

• Royal Society (2002) ''Genetically Modified Plants for Food Use and Human Health.
• Millstone, et al. (1999) 'Beyond Substantial Equivalence' Nature October 7, 1999^*
• OECD (1993) 'Safety Evaluation of Foods Derived by Modern Biotechnology: Concepts and Principles', Paris: Organisation for Economic Cooperation and Development. ^*

Biotechnology | Risk | Food science