Environmental chemical hazards are a highly contentious topic in modern life. Nearly every nation on earth has faced its own environmental crises, and also shares perspectives on the possibility of global catastrophes. Of the many global concerns we face, the environmental issue is unique in many ways. The greatest of these is the fundamental scientific nature of the issue, and the extent to which our opinions are formed based on high-level scientific inquiry and assessment. The two key fields of study on this issue, environmental epidemiology and exposure assessment, are still given separate names because of their separate historical roots and scientific traditions, but are seen increasingly as inseparable aspects of the same basic investigation. In this book, Thomas J. Smith and David Kriebel assert that important advances in the quantification of environmental risks can only come through a true synthesis of the two fields. They have built a common biologic model of exposure, physiologic response, and disease, a synthesis of the various existing models which serves to both simplify and improve the application of environmental epidemiology and exposure assessment to current and future environmental chemical risks. When exposure assessor and epidemiologist agree from the start on the model for their study, the conceptual framework for the study they design and the analyses they carry out are much more likely to yield useful exposure-risk information. An explicit biologic model of the apparent processes linking exposure to disease should form the basis for any study seeking to quantify risk from environmental chemicals.