RESPIRATORY CANCER AND OTHER CHRONIC DISEASE MORTALITY AMONG SILICOTICS IN CALIFORNIA

Silicotics have increased mortality from tuberculosis (TB) and from no nmalignant respiratory diseases (NMRD), including silicosis and silico tuberculosis. Since the publication of the International Agency for Re search on Cancer monograph in 1987 indicating that silica was a probab le human carcinogen, there has been an extensive debate about the canc er risks among silicotics. The authors identified 590 claims for silic osis among a registry of lung diseases compiled from California Worker s' Compensation cases from 1945 to 1975. Using state vital records, we determined the mortality risks from 1946 to 1991. Our findings confir med that these claimants had a significantly elevated risk for all cau ses of death with a standardized mortality ratio (SMR) of 1.30 (95% co nfidence interval [CI] = 1.18, 1.43); TB had a SMR of 56.35 (95% CI = 41.10, 75.40) and NMRD a SMR of 3.80 (95% CI = 3.11, 4.60). Cancers of the trachea, bronchus, and lung had a SMR of 1.90 (95% CI = 1.35, 2.6 0). For malignancies of the large intestine, there was a previously un reported SMR of 2.08 (95% CI = 1.14, 3.50). Mortality from all disease s of the heart was significantly less than expected with a SMR of 0.68 (95% CI = 0.55, 0.83); cancers of the prostate and lymphatic system w ere also significantly low with SMRs of 0.26 (95% CI = 0.03, 0.94) and 0.17 (95% CI = 0.04, 0.97), respectively. Workers with silicosis shou ld be warned about these chronic disease risks, and prevention efforts to control occupational silica dust exposure should become a higher p riority. (C) 1995 Wiley-Liss, Inc.