A worker, who works in indium tin oxide(ITO) factory, was died by a pulmonary disease in 2001. ITO is a compound made up of indium and tin. Tanaka, A, Hirata, M and co-workers collected serum from the patient and reported high concentration of indium in serum. From this report, it seems that indium might be a main risk factor of pulmonary disease caused by occupational exposure to ITO. Tanaka, Hirata and co-workers tried a supplemental examination and found additional 10 patients in Japan. Japan consumes indium maximally in the world, and uses 80% of it to make ITO. Then, Tanaka and Hirata serve notice to people to improve the occupational environment in ITO factories.