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Environmental Effects of Transgenic Plants: The Scope and Adequacy of Regulation
about such changes in scale in APHIS assessments, but large-scale changes are the very kind of environmental changes that make up the primary impacts of modern agriculture (see Chapter 1).
Finding 5.12: APHIS assessments of petitions for deregulation are largely based on environmental effects considered at small spatial scales. Potential effects from scale-up associated with commercialization are rarely considered.
The focus on small-scale field and laboratory tests is evident in the types of tests typically conducted to assess impacts on non-target organisms. For crops that produce Bt toxins, the general types of tests used to assess non-target effects are laboratory toxicology tests similar to those used to assess conventional insecticides. The organism being tested is exposed to the toxin itself (or a closely related toxin) at concentrations 10 to 10,000 times higher than the organism will experience in the field. If the right organism is tested using an appropriate method of exposure (but see Hilbeck et al. 2000, NRC 2000c, Marvier 2001), such testing can be valuable. However, these elevated-dose, acute toxicity tests can miss the effects of a chemical on biological processes other than the one that causes the acute toxicity. For example, testing of many conventional pesticides at maximum tolerated doses did not reveal their estrogenic activity, which can be seen at much lower doses.
Finding 5.13: The “toxicology-type” risk assessments used by petitioners are useful but not sufficient to assess the non-target risks of pesticidal crops.
In addition to laboratory testing, there have been some short-term, small-scale field tests that have examined the effects of transgenic crops on invertebrate biodiversity. It would be possible for applicants to conduct more comprehensive field evaluations of transgenic plants for environmental effects prior to petitioning for nonregulated status than is currently done. A number of the case studies in Chapter 4 point out specific ways that these studies could be improved. However, even more comprehensive and relevant precommercialization field testing would still be limited to detecting effects on organism abundances and field characteristics that occur on small-time and spatial scales.
Therefore, there is a need for a system of testing and monitoring after commercialization, when large-scale plantings begin. Development of such postcommercialization assessments is important, complex, and likely to be quite expensive. The next chapter is devoted to examining the conceptual and practical aspects of developing such postcommercialization assessments.