unintended changes in the levels of endogenous nutrients, toxicants, allergens, or other compounds in all types of GM food—including GE food—that may lead to an unintended adverse health effect. It is important to note that this framework does not treat genetic engineering as a technology that is completely separate from other genetic modification techniques; the flow chart can usefully be applied to the full range of genetic modification technologies.

However, there are limitations to the application of this framework—or any other—because technological advances in analytical chemistry have exceeded our ability to interpret the consequences to human health of changes in food composition. Although compositional changes can be detected readily in food, and the power of profiling techniques is rapidly increasing our ability to identify compositional differences between GE food products and their conventional counterparts, methods for determining the biological relevance of these changes and predicting unintended adverse health effects are understudied. As discussed in this report, further advances in analytical technologies and their interpretation are needed to address these limitations.

Nevertheless, the committee believes that useful assessments currently can be made using this framework, giving consideration to questions such those listed below.

1. What differences exist from the progenitor line?

This question should address the known nutrients, toxicants, and antinutritional factors in order to identify and quantify changes introduced to food, whether intentional or unintentional. Two related questions exist:

  1. What is the relevant progenitor to use as a comparator?

  2. Should all detected differences trigger a requirement for further analytical work?

The selection of the relevant progenitor line is not a trivial issue. Because it is known that the average composition of food crops has changed over time as a result of breeding and changes in agricultural practices, selection of a historical progenitor is not appropriate. The immediate isogenic progenitor line is an appropriate comparator; however, the role of environmental factors on composition must be considered. Similarly, the progenitor’s role in the total diet of target populations must be considered. It is the genome that enables environmental responses, and environmental variables often have been shown to have large effects on composition. The interaction of genotypic and environmental variables must be considered in evaluating compositional effects of genetic modification. Comparisons of the new line with the progenitor, when both are grown under a single set of environmental conditions, would be informative, but not conclusive.

It is proposed that compositional differences attributable to genetic changes be evaluated on a case-by-case basis. In particular, the importance of differences

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