Introduction

Abstract Enviromental epidemiology may be defined as the epidemiologic study of the health consequences of exposures that are involuntary and that occur in the general environment. Such exposures may occur in the air, water, diet, or soil. Examples in these generic categories are respirable particulates in the air, chlorinated hydrocarbons in treated water, toxic contaminants in cooking oil, and lead in the soil. The involuntary nature of these exposures separates environmental epidemiology from other realms of epidemiology. For example, passive smoking falls within the scope of environmental epidemiology because it is involuntary and a public exposure, whereas active smoking is not. Community exposure to lead coming from a local plant is an issue of environmental epidemiology, whereas worker exposure to lead in the plant itself is a problem of occupational epidemiology; study design and methods typically would be quite different for these two populations. Much of in-fectious disease epidemiology is also excluded when transmission of the infectious agent is person-to-person. However, infectious agents encountered in the general environment (e.g., in water supplies) are within the scope of environmental epidemiology.