Lifetime cumulative exposure to rubber dust, fumes and N-nitrosamines and non-cancer mortality: a 49-year follow-up of UK rubber factory workers

Objectives
To examine associations between occupational exposures to rubber dust, rubber fumes, and N-Nitrosamines and non-cancer disease mortality.

Methods
A cohort of 36,441 males aged 35+ years employed in British rubber factories was followed-up to 2015 (94% deceased). Competing risk survival analysis was used to assess risks of dying from non-cancer diseases (respiratory, urinary, cerebrovascular, circulatory, and digestive diseases). Occupational exposures to rubber dust, rubber fumes, N-Nitrosamines were derived based on a population-specific quantitative job-exposure matrix which in-turn was based on measurements in the EU-EXASRUB database.

Results
Exposure-response associations of increased risk with increasing exposure were found for N-Nitrosomorpholine with mortality from circulatory diseases (Sub-hazard ratio (SHR) 1.2; 95%CI 1.1-1.2), ischaemic heart disease (IHD) (SHR 1.2; 95%CI 1.1-1.3), cerebrovascular disease (SHR 1.2; 95%CI 1.1-1.3), and exposures to N-Nitrosodimethylamine with respiratory disease mortality (SHR 1.4; 95%CI 1.3-1.5). Increased risks for mortality from circulatory disease, IHD, and digestive diseases were found with higher levels of exposures to rubber dust, rubber fumes, and N-Nitrosamines sum, without an exposure-dependent manner. No associations were observed between rubber dust, rubber fumes, and N-Nitrosamines exposures with mortality from asthma, urinary disease, bronchitis, emphysema, liver disease, and some digestive diseases.

Conclusions
In a cohort of rubber factory workers with 49 years of follow-up, increased risk for mortality from chronic circulatory, cerebrovascular, respiratory and digestive diseases were found to be associated with cumulative occupational exposures to specific agents.