Mortality of Italian lead smelter workers.

OBJECTIVES: The purpose of this study was to evaluate the health consequences of employment in the lead-smelting industry. METHODS: A mortality study of 1388 workers and laborers in production and maintenance departments was conducted in an Italian lead-smelting plant. The vital status of cohort members was determined from 1950 to 1992. Standardized mortality ratios were calculated for specific causes of death on the basis of national and regional reference rates. The relative risk for selected causes of death was also modeled as a function of age, calendar period, latency, and duration of employment with Poisson regression analysis. RESULTS: A significant 4.5-fold excess mortality from pneumoconiosis and other diseases of the respiratory system was observed, but the risk of pneumoconiosis did not show a significant trend by duration of employment. Mortality from all cancers, stomach cancer, and lung cancer was lower than expected. The standardized mortality ratios for genitourinary diseases and kidney cancer were not significantly elevated, but the Poisson regression analysis showed that both risks increased significantly by duration of employment. CONCLUSIONS: These findings provide limited evidence that long-term employment in lead-smelting plants increases the risk of genitourinary diseases and kidney cancer. The observed increase in mortality from pneumoconiosis and other diseases of the respiratory system was more likely related to silica exposure in other workplaces.

Mortality of Sardinian lead and zinc miners: 1960-88.

The mortality of 4740 male workers of two lead and zinc mines was followed up from 1960 to 1988. Exposure to respirable dust was comparable in the two mines, but the median concentration of silica in respirable dust was 10-fold higher in mine B (12.8%) than in mine A (1.2%), but the mean annual exposure to radon daughters in underground workplaces differed in the opposite direction (mine A: 0.13 working levels (WL), mine B: 0.011 WL). Total observed deaths (1205) were similar to expected figures (1156.3) over a total of 119 390.5 person-years at risk. Underground workers of mine B had significant increases in risk of pulmonary tuberculosis (SMR 706, 95% confidence interval (95% CI) 473-1014) and non-malignant respiratory diseases (SMR 518; 95% CI 440-1606), whereas the only significant excess at mine A was for non-malignant respiratory diseases (SMR 246; 95% CI 191-312). Total cancer and lung cancer mortality did not exceed the expectation in the two mines combined. A 15% excess mortality for lung cancer, increased up to an SMR 204 (95% CI 89-470) for subjects employed > or = 26 years, was, however, found among underground workers in mine A who on the average experienced an exposure to radon daughters 10-fold higher than those of mine B. By contrast, despite their higher exposure to silica, mine B underground workers experienced a lower than expected lung cancer mortality. A ninefold increase in risk of peritoneal and retroperitoneal cancer combined was also found among underground workers of mine A (SMR 917; 95% CI 250-2347; based on four deaths). A causal association with workplace exposures is unlikely, however, as the SMR showed an inverse trend by duration of employment. These findings are consistent with low level exposure to radon daughters as a risk factor for lung cancer among metal miners. Exposure to silica at the levels estimated for the mine B underground environment did not increase the risk of lung cancer.

Lung cancer mortality among female mine workers exposed to silica.

A mortality cohort study (1951-1988) was conducted on 526 female workers in two lead and zinc mines in southwestern Sardinia (Italy), 310 of whom had been exposed to silica. Women exposed to silica showed a nonsignificant 38% increase in the standardized mortality ratio (SMR) for nonmalignant respiratory diseases, which was highest and statistically significant among women at the mine with the highest exposure to silica (SMR = 217; 95% confidence interval [CI] = 104, 400; based on 10 observed and 4.6 expected deaths). Five deaths from lung cancer also occurred among those exposed to silica (SMR = 283; 95% CI = 91,660), but the excess was not related to the level or duration of exposure. No information was available concerning lifestyle risk factors in this cohort. However, smoking was quite rare among Sardinian women at the time cohort members worked, so it may be presumed that very few of them were smokers.