often will bring an umbrella. But for the same reasons that risk itself is complicated, and our intuitive understanding of risk has only tenuous connections to scientific risk analysis, the precautionary principle is complicated and our intuitive understanding of it incomplete.

As discussed more thoroughly in Chapter 7, there is no one precautionary principle, and the precautionary principles range from minor procedural changes in risk analysis to major shifts in the burden of proof. The principle is featured prominently in two international agreements about the risks of transgenic organisms—the Biosafety Protocol of the Convention on Biodiversity (CBD 2000) and Directive 90/220 of the European Union (EU), modified in March 2001 (European Commission 2001). In both cases the precautionary principle is specified ambiguously, so its meaning will evolve and become defined by its use. A close reading of the U.S. coordinated framework for regulating transgenic organisms shows that the framework neither excludes the use of a precautionary principle nor endorses one. Thus, the fate of the precautionary principle will be determined in future applications and negotiations among interested parties. As clearly stated in the biosafety protocol and the modified Directive 90/220, science will continue to be the basis of risk assessment.

SCIENTIFIC ASSUMPTIONS UNDERPINNING REGULATION OF TRANSGENIC CROPS

The Categories of Hazards

The initial step in risk analysis and one of the most critical for framing the entire analysis is hazard identification. A hazard is a potential adverse effect (potential harm) from a proposed activity (e.g., release of a transgenic crop plant). Risk is the combination of a hazard and the likelihood that the hazard occurs. This implies that many hazards are not risks, and the existence of a hazard does not imply significant danger from the activity because the hazard might not happen. The set or scope of identified hazards determines the technical capacity and level of deliberation needed to conduct the analysis and therefore is one of the most critical steps.

Four categories of hazards from the release of transgenic crop plants can be identified: (1) hazards associated with the movement of the transgene itself with subsequent expression in a different organism or species, (2) hazards associated directly or indirectly with the transgenic plant as a whole, (3) non-target hazards associated with the transgene product outside the plant, and (4) resistance evolution in the targeted pest populations. A fifth category of hazard, discussed in the other chapters, is that of indirect effects on human health that are mediated by the environment.



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