Occupational Exposure and New-onset Asthma in a Population-based Study in Northern Europe (RHINE)

OBJECTIVES In a large population-based study among adults in northern Europe the relation between occupational exposure and new-onset asthma was studied. METHODS The study comprised 13 284 subjects born between 1945 and 1973, who answered a questionnaire 1989-1992 and again 1999-2001. Asthma was defined as 'Asthma diagnosed by a physician' with reported year of diagnose. Hazard ratios (HR), for new-onset adult asthma during 1980-2000, were calculated using a modified job-exposure matrix as well as high-risk occupations in Cox regression models. The analyses were made separately for men and women and were also stratified for atopy. RESULTS During the observation period there were 429 subjects with new-onset asthma with an asthma incidence of 1.3 cases per 1000 person-years for men and 2.4 for women. A significant increase in new-onset asthma was seen for men exposed to plant-associated antigens (HR = 3.6; 95% CI [confidence interval] = 1.4-9.0), epoxy (HR = 2.4; 95% CI = 1.3-4.5), diisocyanates (HR = 2.1; 95% CI = 1.2-3.7) and accidental peak exposures to irritants (HR = 2.4; 95% CI = 1.3-4.7). Both men and women exposed to cleaning agents had an increased asthma risk. When stratifying for atopy an increased asthma risk were seen in non-atopic men exposed to acrylates (HR = 3.3; 95% CI = 1.4-7.5), epoxy compounds (HR = 3.6; 95% CI = 1.6-7.9), diisocyanates and accidental peak exposures to irritants (HR = 3.0; 95% CI = 1.2-7.2). Population attributable risk for occupational asthma was 14% for men and 7% for women. CONCLUSIONS This population-based study showed that men exposed to epoxy, diisocyanates and acrylates had an increased risk of new-onset asthma. Non-atopics seemed to be at higher risk than atopics, except for exposure to high molecular weight agents. Increased asthma risks among cleaners, spray painters, plumbers, and hairdressers were confirmed.