Lung Function and Respiratory Symptoms in Hard Metal Workers Exposed to Cobalt

Objective: To follow-up lung function and airway symptoms in workers exposed to cobalt dust at a hard metal plant. Methods: A total of 582 employees underwent spirometry and completed a questionnaire. A historical exposure matrix was created, assigning figures for historical and recent work-related exposure. Results: At the time of employment, 5% reported symptoms from respiratory tract. At follow-up, 5% suffered from persistent coughing and 7% reported asthma; 20% were daily smokers. Among nonsmokers without asthma, an evident, statistically nonsignificant, dose-response effect was seen between increasing cobalt exposure and decline in FEV1 (forced expiratory volume in the first second). In all exposure categories, the FEV1 in smokers declined 10 mL more per year than for nonsmokers. Conclusions: Even low levels of cobalt exposure seem to hamper lung function both in smokers and nonsmokers. This impact is considered low in relation to the effect of aging.