Retrospective Exposure Reconstruction: Reverse Models of Asbestos Health Risk Assessment

Abstract

Background. In the 21st century, asbestos remains a serious and somewhat controversial occupational and environmental hazard. Asbestos-related cancer claims remain the number one toxic tort issue in the world. The development of effective risk assessment approaches for different types of asbestos fiber types is critical to address the existinguncertainty in some exposure evaluation methods. Retrospective exposure reconstruction is tightly connected to risk assessment methodologies. From the scientific viewpoint, exposure reconstruction can be perceived as a reverse model of risk assessment when exposures are evaluated based on the observed health outcomes. Aims. To review improvedasbestos exposure reconstruction methodologies in epidemiology studies and resulting health risk assessment models. To discuss validation and characterization methods of individual and cohort asbesos exposure assessments, based on consistency of mesosthelioma mortality rates. Methods. The reverse versions of the most famous asbestos health risk assessment models (U.S. EPA IRIS, Hodgson and Darnton, Berman and Crump) were applied to mesothelioma mortality data in 19 published cohorts to reconstruct the levels of exposure. Monte Carlo simulation was utilized to reflect the variability of mortality rates and the coefficients of the models. Results. It was demonstrated that the results of exposure reconstruction were consistent with the published exposure levels if the fiber type difference was taken into consideration (correlation coefficients r=0.88 for Berman, Crump model, r=0.82 for Hodgson and Darnton model, P<0.05). Conclusions. The application of reverse models of asbestos risk assessment can play an important role in retrospective exposure reconstructions. Further development is needed, with cross-validation and utilization of additional sources of information, like lung burden measurements and refined evaluation of the morphology of asbestos fibers for different occupational conditions.