Investigation of a lung cancer cluster in the melt shop of an Ontario steel producer.

Workers' concerns about an excess of cancer in an electric arc steelmaking operation were investigated. In comparison with men who had worked elsewhere in the plant, an increased risk of lung cancer death was observed among men who had been employed in the melt shop. The hypothesis that the association might be related to occupational exposures is supported by the persistence of the association when the hypothesis-generating cases were removed from the analysis (p = 0.063) and by a significant trend in the risk of lung cancer with years of exposure in the melt shop. No air sampling had been performed in earlier years. Current environmental analyses in the melt shop found no polycyclic aromatic hydrocarbons (detection limit: 0.001 mg/m3), and silica levels were below 0.1 mg/m3. The carcinogenic metals arsenic and chromium were detected, but their concentrations in earlier years are unknown.