Occupational cancer epidemiology in the coming decades.

Occupational studies have identified many of the established chemical carcinogens. Studies in the next millennium will be needed to identify the hazardous agents in occupations known to have high cancer rates, to assess human risks from animal carcinogens that have not been well evaluated epidemiologically, to provide information on women and minorities, to evaluate interactions with genetic factors and other risk factors, to contribute to our understanding of risks from the spread of chemicals from the workplace to the general environment, and to identify mechanisms of cancer. The traditional retrospective cohort design will be insufficient to meet these needs. Population-based case-control, nested case-control, prospective cohorts, and cross-sectional designs will assume more important roles because of the need to collect information on nonoccupational risk factors and biological tissues. Improvement in the assessment of quantitative exposures is needed for the efficient evaluation of interactions between occupational exposures, genetic factors, and nonoccupational exposures.