Occupational epidemiologic study design and application.

Occupational epidemiologic investigations have provided, and will continue to provide, important information to understand environmental causes of disease. High-quality investigations designed to test hypotheses have several requirements. They must include valid quantitative assessments of exposure, some information on lifestyle risk factors, and include biologic monitoring and marker components whenever possible. Availability of these data allows a clear evaluation of potential confounders and biases, assessment of interaction among risk factors, and provides the opportunity to identify susceptible subgroups.