A Case of Occupational Asthma in Tunnel Workers Exposed to Isocyanates

Occupational asthma is one of the most prevalent occupational lung diseases in the developed countries1). The proportion of the cases of asthma in adults due to occupational exposure is estimated to be 15%. Because occupational asthma may cause long disability, it is important to identify the causes and remove the workers as soon as possible from the causal exposure. One of the main causes of occupational asthma is isocyanates. Because isocyanates are used in the production of polyurethane foams, adhesives, varnishes, insulating materials and hardeners, many cases of occupational asthma due to isocyanates have been reported in many different kinds of occupations2). Pneumoconiosis has been mainly recognized as the occupational lung disease in tunnel workers3). There have been no reports of the occupational asthma due to isocyanates in tunnel workers in Japan, and so there has been less concern about asthma in tunnel workers than about pneumoconiosis. Here we report on a tunnel worker who has been exposed to isocyanate and developed asthma.