Occupational exposure to wood dust and risk of nasal and nasopharyngeal cancer: A case‐control study among men in four nordic countries—With an emphasis on nasal adenocarcinoma

The current study aims to provide stronger evidence to aid in our understanding of the role of cumulative occupational exposure to (softwood‐dominated) mixed wood dust in aetiology of nasal cancer. We included broad exposure occurred in a range of wood‐processing occupation across varied industries in four Nordic countries. A population‐based case‐control study was conducted on all male cases with nasal adenocarcinoma (393 cases), other types of nasal cancer (2,446) and nasopharyngeal cancer (1,747) diagnosed in Finland, Sweden, Norway and Iceland between 1961 and 2005. For each case, five male controls, who were alive at the time of diagnosis of the case (index date), were randomly selected, matched by birth‐year and country. Cumulative exposures (CE)s to wood dust and formaldehyde before the index date were quantified based on a job‐exposure matrix linked to occupational titles derived from population censuses. Hazard ratios (HRs) for the CE of wood dust were estimated by conditional logistic regression, adjusted for CE to formaldehyde and 95% confidence intervals (CIs) were calculated. There was an increasing risk of nasal adenocarcinoma related to wood dust exposure. The HR in the highest CE category of wood dust (≥ 28.82 mg/m³‐years) was 16.5 (95% CI 5.05–54.1). Neither nonadenocarcinoma of the nose nor nasopharyngeal cancer could be linked to wood dust exposure. CE to softwood‐dominated mixed wood dusts is strongly linked with elevated risk in nasal adenocarcinoma but not with other types of nasal or nasopharyngeal cancer.