In food safety, the concept of substantial equivalence holds that the safety of a new food, particularly one that has been genetically modified (GM), may be assessed by comparing it with a similar traditional food that has proven safe in normal use over time. It was first formulated as a food safety policy in 1993, by the Organisation for Economic Co-operation and Development (OECD).

As part of a food safety testing process, substantial equivalence is the initial step, establishing toxicological and nutritional differences in the new food compared to a conventional counterpart—differences are analyzed and evaluated, and further testing may be conducted, leading to a final safety assessment.

Origin

The concept of comparing genetically modified foods to traditional foods as a basis for safety assessment was first introduced as a recommendation during the 1990 Joint FAO/WHO Expert Consultation on biotechnology and food safety (a scientific conference of officials and industry), although the term substantial equivalence was not used. Adopting the term, substantial equivalence was formulated as a food safety policy by the OECD, first described in their 1993 report, "Safety Evaluation of Foods Derived by Modern Biotechnology: Concepts and Principles. The underlying approach of comparing a new product or technique to an existing one has long been used in various fields of science and technology.

In June 1999, G8 leaders requested the OECD to “undertake a study on the implications of biotechnology and other aspects of food safety.” In 2000, the OECD Edinburgh Conference on Scientific and Health Aspects of Genetically Modified Foods was held. Following those discussions, the OECD published an opinion that substantial equivalence is an important tool in analyzing the safety of novel foods, including GM foods. The document noted that substantial equivalence serves as a framework for approaching food safety assessment, rather than functioning as a quantitative standard or measure.

In 2000, a new joint FAO/WHO consultation on foods derived from biotechnology revisited the concept. The group concluded that safety assessment should follow an integrated, step-by-step, case-by-case approach, supported by a structured set of questions. It was reaffirmed that substantial equivalence, when comparing foods derived from genetically modified plants with their conventional counterparts, is the most appropriate strategy for identifying potential safety and nutrition issues. It was also emphasized that substantial equivalence does not replace risk analysis—since it does not directly characterize hazards—but should guide the comparative process in relation to the conventional food used as a reference. The experts considered the methodology used in the safety assessment of genetically modified foods approved commercially to date to be satisfactory and concluded that the application of substantial equivalence strengthens the existing assessment framework. According to the consultation, there were no alternative strategies at the time that offered greater safety guarantees.-->

Assessment of GM food

Substantial equivalence is the starting point for GM food safety assessment: significant differences between a new food item and its conventional counterpart would indicate the need for further testing. A "targeted approach" is taken, by selecting specific relevant molecules for comparison. For plants, selection of a suitable comparator may involve growing the new plant side by side with genetically closely related varieties, or using publicly available composition data for closely related varieties.

  1. Substantial equivalence analysis<br />Considering introduced genes, newly expressed proteins, and new secondary metabolites
  2. Toxicological and nutritional analysis of detected differences<br />Gene transfer, allergenicity, degradation characteristics, bioavailability, toxicity, and estimated intake levels
  3. Toxicological and nutritional evaluation<br />If necessary, additional toxicity testing, possibly including whole foods (return to Phase 2).
  4. Final safety assessment of GM plant

<!--A 2003 review in Trends in Biotechnology identifies seven main components of a standard safety test: that currently available food derived from GM crops poses no greater risk to human health than conventional food, but that each GM food needs to be tested on a case-by-case basis before introduction. Nonetheless, members of the public are much less likely than scientists to perceive GM foods as safe. The legal and regulatory status of GM foods varies by country, with some nations banning or restricting them, and others permitting them with widely differing degrees of regulation, which varied due to geographical, religious, social, and other factors. <!--End of restricted section -->

Technological developments

There has been discussion about applying new biochemical concepts and methods in evaluating substantial equivalence, such as metabolic profiling and protein profiling. These concepts refer, respectively, to the complete measured biochemical spectrum (total fingerprint) of compounds (metabolites) or of proteins present in a food or crop. The goal would be to compare overall the biochemical profile of a new food to an existing food to see if the new food's profile falls within the range of natural variation already exhibited by the profile of existing foods or crops. However, these techniques are not considered sufficiently evaluated, and standards have not yet been developed, to apply them.

Adoption

Approaches to GM food regulation vary by country, while substantial equivalence is generally the underlying principle of GM food safety assessment. This is the case for national and international agencies that include the Canadian Food Inspection Agency (CFIA), Japan's Ministry of Health, Labour and Welfare (MHLW), the US Food and Drug Administration (FDA), and the United Nations' Food and Agriculture Organization (FAO) and World Health Organization.