ABSTRACT
Accurate assessment of exposure to occupational and environmental risk factors is needed to ensure that epidemiological studies meet their objectives in investigating the exposure-disease relationship. This chapter presents improvements in quantifying exposure to occupational and environmental risk factors, starting from very crude assessment by occupation or industries to detailed subject-specific biological effective dose. It covers exposure related methodological issues, such as effects of misclassification of exposure on risk estimates, selection of appropriate exposure indices in the evaluation of exposure-disease relationship, and issues that need to be considered when an epidemiological study is used in risk management or a standard setting. Job exposure matrices are designed to assign a priori exposure levels for study subjects based on their job and industry titles obtained from their work histories in case-control and surveillance studies. In most occupational cohort studies, work histories and historical exposure information are collected from written records existing in the workplace.
