When does similar mean the same: A case for relaxing standards of substantial equivalence in genetically modified food crops

Abstract

The concept of substantial equivalence for genetically modified crops is rapidly evolving, based on precedence set during the development of the first transgenic crops. It is important at this stage to strike a balance between the cost of determination of substantial equivalence and the economical feasibility of using biotechnology for the improvement of minor-use horticultural crops. Potatoes provide a good illustration of the application of substantial equivalence. Precedence set by traditional breeding and historical crop use demonstrates that nutritional and toxicological constituents requiring critical evaluation for potatoes, and probably any crop, are few in number. It also demonstrates that, in general, genetically modified cultivars need not be identical to the cultivars from which they were derived, but simply contain critical components within a historically acceptable range. Exceptions may include constituents that are an important part of cultivar identity and are critical for industry use or those having toxicological properties. For potatoes, key constituents for establishing substantial equivalence in genetically modified cultivars include tuber glycoalkaloids, total solids, sugars (sucrose and reducing), and possibly protein and vitamin C. For glycoalkaloids, total solids, and sugars, comparisons should be made against the original cultivar from which each genetically modified cultivar was derived. Genetically modified cultivars should be equal to, or lower than their original counterparts in glycoalkaloid concentration; they should be about equal to their counterparts in total solids and sugars if processing quality is an issue and the genetically modified cultivar is to be used in the place of the original cultivar. Comparison for protein and vitamin C content should be made against the ranges published for all commercially accepted cultivars. A similar list of key components, their acceptable ranges, and appropriate comparisons must be established for each crop destined for human or animal consumption. By limiting the number of constituents that are considered critical and broadening acceptable parameters for equivalence, one portion of research costs can be held at an affordable level. Maintaining food safety is important in agricultural research. The concept of substantial equivalence provides a good basis for ensuring food safety in genetically modified crop cultivars. However, it can also be a major factor in increasing the price of products derived through biotechnology above the consumer's willingness to pay. Therefore, a common-sense approach should be used for determination of substantial equivalence, especially for the sake of minor-use horticultural crops. This will require a list of essential constituents for each crop, as well as, a compilation of appropriate ranges of variation to serve as comparatives.