FIGURE I-1 When taking into consideration the relationship of health and disease we need to take into account the role of multiple contributing factors. SOURCE: Wilson, unpublished.

environmental factors that can interact with the features in this primary model (see Figure I-1) to influence the disease state.

The definition of environmental health continues to change. In recent years, the field has evolved toward a more holistic view of the effect of environment on health and has recognized the challenges and the opportunities inherent in this broader view in advancing the field. The World Health Organization defines environmental health as the direct pathological effects on health of chemical, physical, and biological agent and of the effects of the broad physical and social environment on human health (World Health Organization, 1986). This definition is one of many examples that not only apply to air, water, and soil, but in the broadest sense to the pathological effect on health of the broad physical and social environment. Considering these and other definitions, the Roundtable began to define environmental health as the human health impact of the holistic environment—one comprised of the natural, built, and social environments. This view superimposes a holistic view of the influence of various environments in which we live, play, and work. The Roundtable continues to look at how socioeconomic factors, the natural environment, and the built environment can interact to impact human health.

Medical science is advancing and developing new and far more precise tools to investigate the linkages between health and the environment. One example is