Occupational disease predictors in the nickel pyrometallurgical production: a prospective cohort observation

BACKGROUND: Pyrometallurgical nickel production exposes workers to a wide range of occupational risk factors, including nickel aerosol, occupational noise and heat, but occupational (compensation) claims do not get enough attention in the literature. We, therefore, aimed to identify and analyze new occupational disease predictors in order to tailor prevention measures in the nickel pyrometallurgical production workers. METHODS: In a prospective observational study, a cohort of workers grouped in 16 occupations (N = 1424, 88% males, median age 39 (interquartile range (IQR) 31–47 years)), was fixed in 2007 at a large nickel production plant in the Russian High North. We then followed the cohort until 2021 and analyzed the association of selected predictors, including exposure to nickel and occupational group, with the risk of an occupational (compensation) claim in a Cox regression analysis. RESULTS: With 18,843 person-years of observation, occupational disease claims were confirmed in 129 workers (9% of the initial cohort, N = 108 men (84%)). Top three diagnoses were chronic bronchitis (3.81 cases/1000 workers/year), sensorineural deafness (2.36 cases/1000 workers /year) and musculoskeletal disorders (1.90 cases/1000 workers/year). Smoking was significantly associated with each diagnosis (adjusted hazard ratio (HR) ranged from 2.56 (95% confidence interval (CI) 1.17–5.57) for bronchitis to 6.69 (95% CI 1.46–30.64) for chronic obstructive pulmonary disease (COPD)). High nickel exposure was associated with occupational bronchitis and occupational asthma, whereas associations of occupational groups were also identified for COPD, asthma and musculoskeletal disorders. CONCLUSION: Smoking, high exposure to nickel and specific exposure in the occupational groups increase the risk of occupational disease claims and should be prioritized directions for targeted intervention.