Are mortality rates similar between jobs in the Queensland coal mine workers’ cohort?

Abstract Background Coal mine workers are exposed to many occupational hazards which may affect mortality including respirable coal mine dust, crystalline silica and diesel engine emissions. Several studies have shown decreased overall mortality, but studies did not define the jobs held, did not include women coal mine workers and lacked smoking data. Methods A cohort of coal mine workers, from Queensland, Australia, was linked to the national death registry. Those who had had a health assessment after 1993 were grouped by job title into eight Work Categories. Mortality by Work Categories were compared to the Australian population to produce standardised mortality ratios (SMRs). Relative mortality ratios (RMR) by sex were calculated comparing risks within the cohort, adjusted for age, era (calendar period) and smoking. Results There were 4,555 deaths among 161,534 men and 196 among 23,967 women with job titles. The median age at inception was 33 (men) and 30 (women) years. SMRs were significantly reduced for men and women. However, compared with other men in the cohort, increased mortality was found from digestive diseases (Maintenance workers and Truck Drivers), respiratory diseases (Construction and Labourers) and accidents (Production, Labourers and Truck Drivers). Circulatory disease mortality was increased for male Production workers adjusted RMR (aRMR) 1.22(95%CI 1.06–1.40), Unexposed Non-Office aRMR 1.64(95%CI 1.15–2.35) and Labourers aRMR 1.48 95%CI (1.00-2.17) and Truck Drivers aRMR 1.21(95%CI 0.95–1.54), while accidental deaths were higher in female cleaners aRMR 3.13(95%CI 1.30–7.57). The suicide rate was higher for men and women in Production jobs. Conclusions Although a relatively young cohort, mortality risk varied by type of work. Risk of death from circulatory causes was increased in some workers, even after adjusting for smoking. Suicide rates are higher for men and women doing Production jobs.