the United States are linked to social and behavioral factors and accidents (McGinnis and Foege, 1993). However, the vast majority of the nation’s health research resources have been directed toward biomedical research, with comparatively few resources devoted to supporting health research on social and behavioral determinants of health (IOM, 2000).

Major demographic transformations are taking place in the United States and around the world that also present public health with new challenges. The population is aging, and this aging is accompanied by an increase in multiple chronic diseases, geriatric conditions, and mental health conditions. We are faced with the challenge of better understanding how to prevent, delay, or mitigate the effects of these diseases, thereby increasing the chances for healthful, functional aging. The U.S. population is also increasing in racial and ethnic diversity. There are large racial and ethnic health disparities reflected in increased rates among minorities of such health problems as heart disease, cancer, accidents, diabetes, and HIV infections. Improving health outcomes for all populations in American society is a major challenge for public health in the 21st century.


Public health professionals have a major role to play in addressing these complex health challenges, but to do so effectively they must have a framework for action and an understanding of the ways in which what they do affects the health of individuals and populations. Several models have been proposed for understanding the forces that impact on health, that is, the determinants of health (Lalonde, 1974; Evans and Stoddart, 1994; IOM, 1999; Kaplan et al., 2000). While each model differs, determinants include broad social, economic, cultural, health, and environmental conditions; living and working conditions; social, family, and community networks; individual behavior; individual traits such as age, sex, race, and biological factors, and the biology of disease. Kaplan and colleagues (2000), Grzywacz and Fuqua (2000), and others propose that the multiple determinants of health are related and linked in many ways. A model of health that emphasizes the linkages and relationships among multiple factors (or determinants) affecting health is an ecological model. An example of the ecological model can be found in Figure S-1. It is important to note that the committee is not recommending any single model, but rather emphasizing the concept that there are linkages and relationships among the multiple determinants of health.

The committee believes that public health professionals must understand this ecological model. They must look beyond the biological risk factors that affect health and seek to also understand the impact on health of environmental, social, and behavioral factors. They must be aware of how these multiple factors interact in order to evaluate the effectiveness

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