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STATEMENT OF L. VAL GIDDINGS, PH.D. VICE PRESIDENT FOR FOOD AND
AGRICULTURE BIOTECHNOLOGY INDUSTRY ORGANIZATION
19 OCTOBER 2000
ON GENE FLOW AND OUTCROSSING: The answer to Question one
is "Yes," but there is an underlying assumption that hybridization and
introgression are intrinsically hazardous. This assumption is not sustainable.
It is important to recall that risk = hazard x exposure. For Bt crops grown in the US (corn, cotton, potatoes) the exposure to the environment of gene flow is low to non existent: for corn the number of sexually compatible plant species that may be receptive to pollen is extremely limited, if not zero; cotton. s sexually compatible relatives are similarly limited both in numbers and distribution; and potatoes are grown on such small acreage as to be effectively irrelevant from an environmental point of view even if they were not vegetatively propagated. But let us turn to the first variable in the equation, hazard.
The Bt traits provide resistance to insect pests. Even if the probability of significant gene flow were high, which data show it is not, it is hard to imagine what negative consequences would follow. Imagine the scenario if a wild or weedy relative were given an ability it did not previously have to resist insect pests. Any ecological significance would depend on whether or not this newfound resistance would eliminate a selection pressure that had previously held its population numbers in check. While theoretically possible, the biogeography and frequency of sexually compatible relatives of corn and cotton is such as to make this possibility moot. It is even possible, however, that if such a scenario were to arise (say in a foreign country/center of origin where sexually compatible relatives are less uncommon) a rare or endangered wild relative of the crop could acquire an increased measure of protection from one of the forces that may threaten it, insect predation . yet another way in which biotech crops might aid the conservation and sustainability of biodiversity.
SAP should advise EPA in unambiguous terms, therefore, that it is scientifically insupportable to assume that introgression per se is hazardous. Care must be taken to identify a plausible negative impact of introgression before requirements should be imposed to document and analyze rates of gene flow. It remains important to place these issues in the context provided by the facts of nature as we find them. These indicate that gene flow among species is not uncommon, even (in evolutionary time) among taxa that are only very distantly related. To try therefore to prevent or mitigate all gene flow regardless of hazard is as logical and realistic as forbidding the tide to return.
With regard to the question of whether isolation distances for seed certification purposes are sufficient "to mitigate gene flow between Bt-crops and wild or feral populations of sexually compatible species" the answer must depend less on the potential for gene flow than the selection pressures that would operate on the wild or feral population receiving the gene flow. Unless a negative impact of introgression can be identified, i.e a specific hazard that would result from the gene flow (and the introduction of new genetic material per se cannot qualify, else we should expect regulations to mitigate the impact of omnipresent naturally mutagenic agents such as cosmic rays and errors of recombination) it is difficult to conjure scientific justification for any isolation distance whatsoever.
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