Occupational exposure and severe pulmonary fibrosis

BackgroundExternal agents, especially metal and wood dust, are believed to be risk factors for development of idiopathic pulmonary fibrosis (IPF). The aim of this case–control study was to investigate which occupational exposure types are associated with development of severe pulmonary fibrosis (PF), and especially IPF.MethodsAn extensive postal questionnaire including 30 specific items regarding occupational exposure was completed by 181 patients with severe PF and respiratory failure reported to the Swedish Oxygen Register, among whom 140 were judged as having IPF. The questionnaire was also completed by 757 control subjects. We stratified data for age, sex and smoking and calculated odds ratios (ORs).ResultsWe found increased risk for IPF in men with exposure to birch dust (OR 2.7, 95% confidence interval (95% CI) 1.30–5.65) and hardwood dust (OR 2.7, 95% CI 1.14–6.52). Men also had slightly increased ORs associated with birds. We did not find any increased risk in association with metal dust exposure.ConclusionExposure for birch and hardwood dust may contribute to the risk for IPF in men.