Incidence of rhinitis and asthma related to welding in Northern Europe.

Welding-related asthma is well recognised but less is known about rhinitis in relation to welding. The aim here, was to study associations between welding, rhinitis and asthma in a general population sample, and factors influencing selection into and out of a welding occupation.Adult-onset asthma and non-infectious rhinitis were investigated in the international multicentre population-based Respiratory Health in Northern Europe (RHINE) study, including 16,191 responders aged 26-54 years. Ever welding (n=2181), welding >25% of working time (n=747), and welding in stainless steel >6 months (n=173) were assessed by questionnaire. Subjects with rhinitis or asthma onset when aged <18 years were excluded. Incidence rates for asthma and rhinitis were calculated from year of disease onset, and start and end of welding job. Cox's proportional hazard models adjusting for age, sex, parental education and study centre, and Kaplan-Meier curves were used.Rhinitis incidence was higher among welders (hazard ratio (HR) 1.4, 95% CI 1.3-1.6), consistent in men and women, and across centres (pheterogeneity=0.4). In men, asthma incidence was higher among welders (HR 1.4, 95% CI 1.04-1.97). Quitting welding was indicated higher after adult-onset rhinitis (HR 1.1, 95% CI 1.0-1.3). Adult-onset rhinitis and asthma was higher among welders, consistent across population samples from Northern Europe. No pre-employment selection was found, whereas selection out of welding jobs was suggested.