Emphysema type in relation to silica dust exposure in South African gold miners

The relationship between silica dust exposure in gold mines and the type of emphysema was studied in a group of 1,553 white gold miners who had undergone autopsy examination between 1974 and 1987. Of particular interest was the contrast between centriacinar and panacinar emphysema as they relate to silica exposure and the presence of silicosis. Subjects with significant emphysema, that is, with an emphysema score of 30% or more, were classified as having predominantly panacinar or predominantly centriacinar emphysema, and compared to those without emphysema (emphysema score less than or equal to 10%). Of those who had significant emphysema (greater than or equal to 30%), 24% had predominantly panacinar, 43% predominantly centriacinar, and 33% were classified as mixed. The odds ratios (OR) for the association between each emphysema type and dust exposure (one unit of the cumulative dust index) were found to be statistically significant and of equal magnitude [1.019, with a 95% confidence interval (CI) of 1.005 to 1.033 for panacinar and 1.019 with a 95% CI of 1.007 to 1.031 for centriacinar emphysema]. In 163 nonsmokers insignificant panacinar emphysema was more common than centriacinar emphysema. The results indicate that a miner with 20 yr in high-dust occupations has a 3.5 (1.7;6.6) times higher odds of having a significant degree of emphysema at autopsy than a miner not in a dusty occupation. This is likely to be true of smoking miners only because there were only four nonsmokers with an emphysema score between 30 and 40%.(ABSTRACT TRUNCATED AT 250 WORDS)