Improving the use of epidemiologic data in health risk assessment

Epidemiologic data with quantitative exposure measures is infrequently available for specific environmental agents. This lack of exposure measures creates confusion in interpreting epidemiologic data and therefore has impeded its efficient use in health risk analysis. This paper discusses screening and evaluating epidemiologic studies for use in assessing health risk. It also describes the larger role of epidemiology in reducing uncertainties in risk analysis. The approach recognizes that the various designs used to increase statistical power and to control for covariables have different functions in contemporary risk assessment as practiced by regulatory agencies. Each of these study designs is categorized for its role in risk analysis as useful for hazard identification or for dose-response assessment. Studies presenting geographic correlations are construed to be not directly useful in health risk assessment. The numerical level of the exposure data is a deciding factor in using valid epidemiologic studies. However, data measured on an ordinal scale can be used in qualitative assessments and can demonstrate the strength of the relationship. The application of this procedure is illustrated using epidemiologic studies on the carcinogenicity of chemicals contaminated with dioxins.