Food Safety - The Oxford Topic of Food, Politics, and Society - page 597

to confirm if intended changes in composition have occurred, if new metabolites that
were intended to be present are being produced, and if any unintended changes in com-
position have occurred (Cellini et al., 2004). The composition of each crop variety is
different, each contributes different macro- and micronutrients to human and animal
diets, and each can contain different toxicants, food allergens, antinutrients, and poten-
tially beneficial phytochemicals (Chassy, 2010). As a consequence, a unique panel of
constituents must be analyzed with each crop. Lists of key analytes have been compiled
by expert panels and published by the OECD.9 These expert consensus documents also
provide detailed information about the crop; its cultivation; processing; and food, feed,
and industrial uses, with particular emphasis on its importance in human nutrition.
Compositional analysis is used to confirm that no potentially harmful changes such as
losses in a key nutrient or increases in a known antinutrient have occurred.
A thorough knowledge of composition allows the risk assessor to evaluate nutri-
tional value, and any potential toxic or allergenic effects. Nutrition, toxicological, and
other studies documented in the literature describe the biological activity of each food
constituent in detail. The effect of a food or feed on an organism can be computed and
depends directly on the composition of the food or feed, how much is consumed, and
how often it is consumed. If differences in composition are observed, it is also possible
to evaluate any possible biological significance of the differences. Changes in composi-
tion are not per se harmful and, as is discussed later, differences in composition are often
observed in a comparison of varieties of the same crop (Chassy et al., 2004).
Comparison of the composition of a new variety with other varieties is necessary
to determine if changes in composition have occurred as a result of the breeding pro-
cess. If differences in composition are observed, the significance of each difference
must be evaluated through further study. This comparative process has been called
the Substantial Equivalence (SE) paradigm. There has been much confusion, some
perhaps deliberate, about the meaning of the SE process. It is often claimed that the
evaluation proves that, when a product is concluded to be substantially equivalent,
the new variety is safe. Critics of the paradigm argue that a new transgenic variety can
never be identical to its conventional counterpart. There has been much polemical
debate in the literature about this point, so it is important to be very clear about what
SE is and is not. The framers of the paradigm noted that most components would be
present in a new variety at concentrations very similar to those found in the parental
variety and were thus likely to pose no new hazards. They asserted that since the two
varieties being compared were substantially equivalent with respect to most compo-
nents, safety assessors needed only to focus on the observed differences. The compo-
sitional comparison with which the SE paradigm begins is a jumping-off point, not a
conclusion. The process identifies differences; since changes in composition are not
per se risky, the biological and nutritional consequences of any observed differences
must be evaluated further (Chassy et al., 2004; Chassy et al., 2008). It is, therefore,
improper to assert that two plants are substantially equivalent. It is preferable to con-
clude that no biologically meaningful differences were identified through application
of the SE paradigm.