Exposure assessment methods for a study of mortality and cancer morbidity in relation to specific petroleum industry exposures

Storylines of research on resource extraction and health in Canada: A modified metanarrative synthesis

Patterns of research on resource extraction's health effects display problematic gaps and underlying assumptions, indicating a need to situate health knowledge production in the context of disciplinary, corporate and neocolonial influences and structures. This paper reports on a modified metanarrative synthesis of 'storylines' of research on resource extraction and health in the Canadian context. Peer-reviewed articles on mining or petroleum extraction and health published between 2000 and 2018 and dealing with Canadian populations or policies (n = 87) were identified through a systematic literature search. Coding identified main disciplinary traditions, methodologies and approaches for judging high-quality research. Underlying assumptions were analyzed in terms of models of health and well-being; resource extraction's political economic drivers; and representations of Indigenous peoples, territories and concerns. Findings included a preponderance of occupational and environmental health studies; frequent presentation of resource extraction without political economic antecedents, and as a major contributor to Canadian society; sustainable development aspirations to mitigate health impacts through voluntary private-sector governance activities; representations of Indigenous peoples and concerns ranging from complete absence to engagement with legacies of historical trauma and environmental dispossession; and indictment of corporate (especially asbestos industry) and government malfeasance in a subset of studies. Canada's world-leading mining sector, petroleum reserves and population health traditions, coupled with colonial legacies in both domestic and overseas mining and petroleum development, make these insights relevant to broader efforts for health equity in relation to resource extraction. They suggest a need for strengthened application of the precautionary principle in relation to resource extraction; nuanced attention to corporate influences on the production of health science; more profound challenges to dominant economic development models; and extension of well-intentioned efforts of researchers and policymakers working within flawed institutions.

Evaluation and comparison of three exposure assessment techniques

This study was conducted to verify the performance of a recently developed subjective rating (SR) exposure assessment technique and to compare estimates made using this and two other techniques (trade mean, or TM, and task-based, or TB, approaches) to measured exposures. Subjects (n = 68) each completed three full-shift noise measurements over 4 months. Individual measured mean exposures were created by averaging each subject's repeated measurements, and TM, TB, and SR estimates were created using noise levels from worksites external to the current study. The bias, precision, accuracy, and absolute agreement of estimates created using the three techniques were evaluated by comparing estimated exposures with measured exposures. Trade mean estimates showed little bias, while neither the TM nor the SR techniques produced unbiased estimates, and the SR estimates showed the greatest bias of the three techniques. Accuracy was essentially equivalent among the three techniques. All three techniques showed poor agreement with measured exposures and were not highly correlated with each other. Estimates from the SR technique generally performed similarly to the TM and TB techniques. Methods to incorporate information from each technique into exposure estimates should be explored.

The role of exposure reconstruction in occupational human health risk assessment: current methods and a recommended framework

Exposure reconstruction for substances of interest to human health is a process that has been used, with various levels of sophistication, as far back as the 1930s. The importance of robust and high-quality exposure reconstruction has been recognized by many researchers. It has been noted that misclassification of reconstructed exposures is relatively common and can result in potentially significant effects on the conclusions of a human health risk assessment or epidemiology study. In this analysis, a review of the key exposure reconstruction approaches described in over 400 papers in the peer-reviewed literature is presented. These approaches have been critically evaluated and classified according to quantitative, semiquantitative, and qualitative approaches. Our analysis indicates that much can still be done to improve the overall quality and consistency of exposure reconstructions and that a systematic framework would help to standardize the exposure reconstruction process in the future. The seven recommended steps in the exposure reconstruction process include identifying the goals of the reconstruction, organizing and ranking the available data, identifying key data gaps, selecting the best information sources and methodology for the reconstruction, incorporating probabilistic methods into the reconstruction, conducting an uncertainty analysis, and validating the results of the reconstruction. Influential emerging techniques, such as Bayesian data analysis, are highlighted. Important issues that will likely influence the conduct of exposure reconstruction into the future include improving statistical analysis methods, addressing the issue of chemical mixtures, evaluating aggregate exposures, and ensuring transparency with respect to variability and uncertainty in the reconstruction effort.