ABSTRACT
Human exposure assessment is rapidly evolving into a field of its own, as exemplified by the foundation of the International Society for Exposure Analysis. Environmental epidemiology is the study of the distribution of human health and disease in relationship to exposure to environmental agents. The validity of a measure of exposure refers to the agreement between this measure and the true exposure. An important feature of the precision of exposure assessment for the epidemiologist is that the relative precision is more important than the absolute precision. Bias in epidemiology refers to the difference between the estimated association between exposure and disease, and the true association. Often, the environmental epidemiologist is interested in the effect of environmental exposures on chronic diseases such as lung cancer. Many pollutants are so dispersed in the environment that they can reach the human body through a complex variety of environmental pathways.
