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Environmental Effects of Transgenic Plants: The Scope and Adequacy of Regulation
the nucleotide sequence of the genetic modifications, of the transgenic soybeans. The difference between these soybean lines and regular soybeans is clear; the transgenic soybeans carry a tiny additional piece of DNA, an addition of less than one one-hundredth of 1% of the total DNA in the soybean.
Conventional mutant soybeans (Kinney 1994) manifest an unstable increase in oleic acid in the seed oil. The genetic mechanism by which this trait is achieved is unknown, but it must be the result of genetic modifications in the soy genome. Mutagenesis may have altered the amount of DNA, either by destroying portions of the genome or by causing a duplication (perfect or imperfect) of portions of the genome. In any case, it is likely that several genes were altered, not just those regulating oleic acid content. Any number of genes relating to environmental fitness, production of antinutritional compounds, or other undesirable consequences also may have been altered. But APHIS does not assess these new crop cultivars because, as noted above, the current trigger for regulatory review limits oversight to plants altered using rDNA breeding methods. This is not to suggest that new crop varieties developed solely by conventional breeding should be regulated as stringently as transgenic varieties currently are. Despite the genetic uncertainties and unknown consequences of conventional breeding, as noted in Chapter 1, real damage to the environment from new crop varieties is rare. Nevertheless, the additional knowledge of the genetic changes in transgenic varieties allows, in this particular case study, more confident and reliable predictions of environmental (as well as health and nutritional) effects than conventional varieties. There is no indication that the risks associated with these transgenic soybean lines differ in any material way from those of the same species with similar but non-transgenic based attributes. High oleic acid oil soybean varieties, regardless of how the varieties were derived, appear to present similar degrees of hazard.
Also, APHIS did not consider the effect of large-scale commingling of the high-oleic soybeans with regular soybeans, as that might adversely affect the quality of the processed commodity (soybean oil) but not the plant pest characteristics. The transgenic lines will be grown in a segregated identity-preserved manner to avoid commingling with regular soybeans. Any significant inadvertent mixing of the transgenic soybeans and conventional ones could be problematic because the resulting oil would be a blend of high and low oleic acids, the exact proportions depending on the ratio of the blend. The uncertainty of the final oil composition could adversely affect the value of the commodity oil product. While not an environmental risk, it is a potential impact on other agricultural commodities that are part of APHIS’s charge to review. This is true of all identity-preserved crops being grown.