8286758 Nickel, cobalt, and respiratory cancer: unmasking the relationship with lower occupational exposures and potential impact on public health

<h3>Objective</h3> The green shift from fossil fuel to renewable energy depends on extensive use of batteries based on metals, whereof some are known or suspected carcinogens. Revisiting the effects of metal exposures on health outcomes, including cancer, is urgently needed. This study aims to provide new insight into low-grade or long-term exposure to air-borne nickel compounds (recognized human carcinogens) and cobalt (recently classified by the International Agency for Research on Cancer as probably carcinogenic). <h3>Material and Methods</h3> A cohort of Norwegian metal refinery workers (n=18,000) employed 1910–2018, will be linked to data from the Cancer Registry of Norway for follow-up 1953–2024. Department-time exposure matrices with average exposure to total nickel (1910–2018) or cobalt (1952–2018) will be linked to individual work histories. Data on total mortality will facilitate evaluation of competing risk adjusting for smoking by use of historical data. Internal comparisons among refinery workers will be conducted by regression methods and more advanced causal inference methods within a time-to-event analytic framework. Additionally, spatial data analysis and correlation statistics will be used for an ecological study of residents based on regional cancer rates and county-level cigarette consumption. A negative control outcome approach will address potential residual confounding. <h3>Results</h3> Exposure-related cancer risks will be evaluated in the cohort analyses. We will evaluate spatial and temporal patterns of associations between metals measured in moss and ambient air, and county-level lung and sinonasal cancer. This is particularly relevant in the counties of Agder and Finnmark where emissions are assumed high due to nearby metal smelters or refineries. <h3>Conclusion</h3> The present study has an occupational component and an environmental component, both with high quality exposure and cancer data. This approach will attack the research questions from several angles and provide important insights both on the individual and aggregate level.