Exposure-Response Relationships For Platinum Salt Sensitization In Platinum Refinery Workers: A 17-Year Retrospective Study

Background and Aim: Occupational exposure to soluble chlorinated platinum salts, commonly called chloroplatinates, is a known cause of platinum salt sensitization (PSS) and occupational asthma among precious metal refinery workers. The aim was to analyze time trends of chloroplatinate exposure, and exposure-response relationships for PSS in a long-running cohort of platinum refinery workers. Methods: A 17-year retrospective study (2000-2016) was conducted using routinely collected data from five platinum refineries. In total, 1,614 workers who entered the industry since 2000 regularly underwent skin prick tests to diagnose PSS. Exposure to chloroplatinates was measured in 2,982 personal air samples. A Bayesian hierarchical model was used to estimate refinery and job-specific geometric mean exposure levels. The relationship between time-varying exposure levels and PSS development was analyzed by Cox proportional hazards regression, adjusting for smoking and atopy. Results: An overall decreasing trend in chloroplatinate exposure levels was observed through the years. PSS was diagnosed in 117 workers (1.48 per 100 person-years), all with exposure levels below 500 ng/m3 at the time of PSS development. A statistically significant quantitative exposure-response relation between PSS and cumulative, average, and current exposure was found. Conclusion: A clear exposure-response relation between chloroplatinates and PSS was found. Despite a general decrease in chloroplatinate concentrations over time, exposure still leads to PSS incidence, even in the lowest exposure ranges. The widely adopted occupational exposure limit of 2000 ng/m3 does not adequately prevent PSS.