Cancer incidence and mortality among persons in the Finnish Register of Employees Exposed to Carcinogens, 1979-2018

It has been estimated that 2% to 8% of cancers in high-income countries are linked to carcinogenic exposures in workplaces. In Finland, employers are obliged by law to provide data annually on selected carcinogens and carcinogenic working processes to the Finnish Register of Employees Exposed to Carcinogens (ASA). In this study, we expand the follow-up period of a previous study on cancer incidence in exposed employees by 16 years and add estimates of cancer mortality.

The study population included all 142,204 workers registered in ASA from 1979 to 2018. For the cancer follow-up, the data were linked to the Finnish Cancer Registry. To compare the incidence and mortality with those of the Finnish general population, we estimated standardized incidence ratios (SIRs) and standardized mortality ratios.

A total of 12,687 cancer cases and 3,640 cancer deaths were reported among ASA workers over time by the end of 2019. In the entire ASA cohort, the all-site cancer incidence was similar to the general population (SIR 0.98, 95% confidence interval [CI] 0.96 to 0.99). Persons exposed to asbestos showed an excess incidence of mesothelioma (SIR 1.80, CI 1.17 to 2.66) and small cell carcinoma of the lungs (SIR 1.32, CI 1.02 to 1.67). Exposure to hardwood dust (oak and beech) was associated with an increased incidence of nasal cancer (8.69, 1.05 to 31.4), specifically nasal adenocarcinoma (SIR 58.3, CI 7.06 to 211). Increased mortality was observed for exposure-cancer combinations that also showed increased cancer incidence.

This study demonstrated the strongest confirmed associations between occupational exposures and cancer. The absence of many known exposure-cancer associations may point to low levels of exposure among workers registered in ASA or to small effect sizes of the agents investigated.