the genome of incomplete or inappropriate signals. The data to confirm this underlying assumption are limited but consistent across species” (FDA, 2003).



Historically, equivalence of tissue or food composition has been an important component of the regulatory process to evaluate food safety (CAST, 2001; Falk et al., 2002; Juskevich and Guyer, 1990). For genetically modified (GM) plants and the animal biotechnologies reviewed by FDA, the evaluation has included comprehensive compositional analyses of plants, tissues, and milk when appropriate. The committee found that a comparable approach for products from cloned animals—primarily meat and milk—would be an appropriate, scientifically based method for assessing compositional equivalence. Implicit to such assessments is that no increased health risk would be expected if the compositional analyses of animal products from cloned and noncloned animals were substantially equivalent.

Substantial Equivalence

Establishing equivalence of composition is evidence that substantive compositional changes did not occur in the animal as the result of the genetic modification event. Based on studies with GM plants, substantial equivalence is analogous to “as safe as its conventional counterpart” (CAST, 2001). The approach of substantial equivalence, however, is not absolute. Numerous biotechnology approaches developed in animal agriculture have been to intentionally design genetic modification to effect changes in the composition of target nutrients or other molecules (for review, see Karatzas, 2003; Niemann and Kues, 2000). Thus the process of assessing compositional equivalence needs to be undertaken and accommodated for with this in mind.

For example, cloned transgenic cows have been developed that produce milk with a marked increase in β-casein and k-casein (Brophy et al., 2003). Transgenic pigs have been produced that overexpress the bGH gene, which is associated with a dramatic reduction in carcass fat (85 percent reduction) and constituent fatty acid classes (Solomon et al., 1994). Genetic modification to change levels of selected nutrients in plants and animals has been, and is, an important objective of genetic engineering strategies to create designer foods (CAST, 2003; Falk et al., 2002). From the perspective of modifying the nutrient profile of foods, this has been done to increase beneficial nutrients or to decrease nutrients associated with adverse health effects, such as saturated fatty acids.

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