Michigan and New Jersey in the United States maintain silicosis disease registers. In 1988--1992, 372 cases of silicosis were confirmed in Michigan, and, in 1979--1992, 288 were confirmed in New Jersey. A proportionate mortality ratio (PMR) analysis was performed on data from 292 deceased silicotics. Increases in PMR values were found for nonmalignant respiratory disease (NMRD) and lung cancer. The PMR values for NMRD were statistically elevated in all the analyses. The overall proportionate cancer mortality ratio (PCMR) for lung cancer was 1.78 [95% confidence interval (95% CI) 1.22--2.61]. For patients having ever smoked cigarettes, the PCMR for lung cancer was 1.82 (95% CI 1.18--2.81). Never smoking silicotics had a lung cancer PCMR of 1.48 (95% CI 0.43--2.86). For those who had never applied for workers' compensation the corresponding PCMR was higher, 2.10 (95% CI 1.21--3.69), than for those who had applied, 1.45 (95% CI 0.70--2.99).

Key terms cigarette; lung cancer; obstructive lung disease; silica; workers' compensation