8261106 Trends in occupational exposure to inhalable nickel in France, 1987–2024

<h3>Objective</h3> Nickel is a prevalent lung carcinogen and sensitizer with an estimated 100,000 workers exposed in France. We aimed to evaluate trends in occupational exposure levels to inhalable nickel in French workplaces since 1987. <h3>Material and Methods</h3> We sourced inhalable nickel measurements from the Colchic database, which contains exposure data collected in France for risk prevention purposes, restricted to personal samples with a sampling duration ≥2 hours. We used Bayesian hierarchical models to estimate relationships between nickel concentrations and sample year, accounting for censored data and repeated measurements within workplaces. We fit the models to all data and to industrial sectors (3-digit codes, ISIC revision 4) that had ≥20 measurements in each of the following time windows: 1987-1996, 1997-2006, 2007-2015, and 2016-2024. <h3>Results</h3> The whole dataset contained 8,230 measurements, with a median of 201 per year (range 68-482). Non-detects represented 29% of all measurements. Geometric mean concentrations by period ranged from 0.013 mg/m3 for 1987-1996 to 0.003 mg/m3 for 2016-2024. The proportion of samples exceeding the French exposure limit (0.1 mg/m3) decreased from 18% in 1987-1996 to 4% in 2016-2024. Overall geometric mean nickel concentrations decreased by 3.9% per year (95% credible interval 3.1-4.6%). Nine sectors had ≥20 measurements in all periods. All had trends of lower exposures over time, ranging from 3.3%/year (Manufacturing of other general machinery, n=267) to 9.1%/year (Manufacturing of medical and dental instruments and supplies, n=511). <h3>Conclusion</h3> Our analysis of historical inhalable nickel exposure data showed a generalized decrease in workplace concentrations across multiple sectors, although additional studies are needed to also assess trends in respirable nickel exposure. <h3>Funding</h3> Internal funding from the INRS.