Advancing the Contribution of Occupational Epidemiology to Risk Assessment

The identification and quantification of risk factors that are characterized by low exposure levels, moderately increased risks, and unspecific exposure-disease relations is a major challenge facing risk assessment today. Occupational epidemiological studies can play a role in addressing this challenge. The main advantage of occupational epidemiological studies over other potential sources of information for risk assessment (primarily animal bioassays) is that in these studies humans are being investigated, rendering the extrapolation of study results from animals to humans unnecessary. However this advantage is also a disadvantage because occupational epidemiological studies are mostly observational by nature which makes them prone to bias. Although some limitations of the use of occupational epidemiological studies in risk assessment are inherent to the discipline, improvements in the design, conduct and interpretation of studies will likely enhance their use in risk assessment. Furthermore, recent developments in the field of molecular biology and the related increase in the understanding of carcinogenesis and other adverse health effects have opened opportunities to further advance the contribution of occupational epidemiological studies to risk assessment. This thesis consists of a set of approaches that can be used as a framework to advance the use of occupational epidemiological studies in risk assessment. The approaches focus on the evaluation of the quality of occupational epidemiological studies for risk assessment, the incorporation of differences in study quality in methods for evidence synthesis, and the incorporation of biomarkers in occupational epidemiological studies. Some of the approaches are ready to be applied in risk assessment. Other approaches need further development before their actual value for risk assessment can be assessed. Further progress in the use of occupational epidemiological studies in risk assessment should come from tailoring study designs to the needs of risk assessment. A strong focus on high quality quantitative exposure assessment in the design of new occupational epidemiological studies and transparency of the steps undertaken to develop quantitative exposure estimates would significantly contribute to an increased weight of evidence for risk assessment and would likely improve the overall quality of risk assessment for many exposures.