ABSTRACT
This chapter provides an overview of the basic concepts and methods of study used in environmental epidemiology. One approach that epidemiologists take to identify factors that cause or influence disease occurrence is to evaluate time, person, and place characteristics. Diseases which result in mortality are of considerable interest for public health assessment because of the suffering and cost associated with death, particularly when it occurs at a young age. Measurement of exposure is a component of epidemiologic studies in which the objective is to assess a relationship between an environmental contaminant and a disease. The larger the value of relative risk, the more convincing the evidence that an etiological relationship exists between exposure and the disease. Another measure of disease occurrence is the standardized mortality ratio, a measure of risk relative to that of another population called the standard or reference population. The cross-sectional study evaluates the prevalence of a disease or illness in a population.
