Previous NAS committees have examined a number of issues related to the safety of genetically engineered organisms (NRC 1984, 1987, 2000c), but none specifically examined how the commercial use of all genetically engineered crops could affect agricultural and nonagricultural environments. The task set before this committee specifically included provision of guidance for assessment of the cumulative effects of commercialization of engineered crops on agricultural and nonagricultural environments. Therefore, in this report the committee examines potential effects on the environment that could result from the use of engineered crops on large spatial scales and over many years. In addition to evaluating the potential environmental impacts of single engineered traits in existing agricultural systems, the committee also examines how commercialization of engineered crops with single and multiple traits could actually change farming and thereby impact agricultural and nonagricultural landscapes of the United States. In this report the committee uses the current ecological and risk assessment literature in developing what it finds to be an appropriate framework for assessing the environmental effects of genetically engineered products, and then uses this framework to evaluate APHIS’s regulatory process.

The remainder of this introductory chapter presents background information on a set of topics that must be understood before a realistic environmental risk assessment framework can be developed. First, historic evidence is examined of how changes in agricultural technologies and practices have affected surrounding habitats so that readers can gain a sense of the extent of possible interactions. There has been much debate about the potential for genetic modification of crops to cause environmental impacts of a magnitude similar to that caused by the introduction of completely new species. Therefore, the next section of this chapter presents information on the history of environmental effects of conventional crop breeding compared to that of introduced species and also examines the hypothesis that the degree of environmental risk is related to the number of genetic changes introduced into an ecosystem. Next, an in-depth assessment is presented of predictable and unpredictable aspects of both conventional and transgenic processes used to add novel genes to plants. An understanding of the differences and similarities between these methods should give readers a basis for judging how different the side effects of the genetic engineering process can be compared to the side-effects of traditional processes of crop improvement with which we now live. The chapter ends with a brief description of the U.S. Coordinated Framework for the Regulation of Biotechnology and the USDA’s role and authority in regulating transgenic crops.

This introductory chapter leads to six detailed chapters. Chapter 2 uses the general principles of ecology and risk analysis to develop a frame-



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