Respiratory health of cobalt production workers.

Background: Cobalt production workers are exposed to metallic cobalt and nickel and their compounds and to different irritant gases. The aim of our study was to determine whether long-term exposure is associated with an increased occurrence of respiratory symptoms and findings or diseases, other than asthma, which is a known hazard, among cobalt processing workers.

Methods: The study population was comprised of 110 current and former cobalt workers who had worked more than 10 years in a cobalt plant. The reference group consisted of 140 unexposed workers. All the participants were men. The analysis was based on exposure history, pulmonary function, chest X-ray findings, and symptom questionnaires.

Results: Symptoms of asthma based on questionnaire responses were statistically more prevalent among the exposed workers. The respiratory flow rates MEF25 and MEF50, which refer to smaller airways, were significantly lower among the smoking exposed workers than among the smoking unexposed workers. The causative factors of these symptoms and pulmonary function changes could not be determined by the study. One new case of cobalt asthma and one case of allergic asthma were diagnosed in the exposed population. No cases of hard metal disease or fibrosing alveolitis were found.

Conclusions: No chronic respiratory diseases, except asthma, were found among cobalt production workers in this study.