Ss24-02 Challenges and Opportunities in Occupational Exposure Characterization of Carcinogens for Cancer Hazard Identification

Introduction The other two presentations in this session highlight examples of IARC Monographs evaluations in which studies in exposed workers provided important evidence on cancer in humans or mechanisms of carcinogenesis. Since the update of the Preamble in 2019, the IARC Monographs contain a formal critical appraisal of the exposure assessment quality in human cancer and mechanistic studies. This presentation describes the workflow of this procedure and applications to some examples. Materials and Methods The steps of the exposure assessment critique as outlined by the IARC Monographs Preamble are presented. Former Monographs evaluations were used as case studies to identify the exposure assessment domains that were most informative for judging study quality. Results A common approach was used to evaluate the exposure assessment quality in the Monographs on (i) 1,1,1 trichloroethane, (ii) antimony and (iii) occupational exposure as a firefighter. Some criteria were adjusted for different agents, such as the studies’ definition of the exposure, information on exposure routes, and the assessment of co-exposures. Agent-specific knowledge is required concerning exposure assessment methods and potential co-exposures to identify the strengths and limitations of the exposure assessments performed in human cancer and mechanistic studies. Conclusions Evaluating the quality of exposure assessment methods in studies with exposed humans is a critical step needed to judge the studies’ quality and informativeness. The structured process formally introduced since the new Preamble can improve transparency and consistency in the application of evidence synthesis frameworks for future IARC working groups and other scientific review panels.