Mortality from cardiovascular diseases and sudden death in ferroalloy plants.

OBJECTIVES

The aim of this study was to examine mortality from circulatory diseases and sudden death among workers in 12 Norwegian ferroalloy plants.

METHODS

The cohort comprised 14730 men employed for the first time during 1933-1990 and for at least 6 months. Deaths observed during 1962-1990 were compared with expected figures calculated from national mortality rates. Internal comparisons of rates were performed by Poisson regression analysis.

RESULTS

The overall mortality from cardiovascular diseases was not increased [standardized mortality ratio (SMR) 1.01], but a significantly increased mortality from sudden death (SMR 1.55) and hypertensive disease (SMR 1.37) was observed. Among the ferromanganese/silicomanganese (FeMn/SiMn) furnace workers the sudden death mortality was significantly increased during the employment period (SMR 2.47). In an internal comparison of the sudden death rates, a significant increase of 0.05 in the rate ratio per workyear was observed in this group. The mortality from 3 hypertension-related diseases combined (cerebrovascular, hypertensive, and renal diseases) showed identical positive mortality trends among the ferrosilicon/silicon-metal (FeSi/Si-met) and the FeMn/SiMn furnace workers by increasing duration of work.

CONCLUSIONS

Increased mortality from sudden death among the FeMn/SiMn furnace workers is not likely to be explained by smoking or alcohol consumption. Associations with work exposures (manganese and possibly carbon monoxide and heat) are suspected. The increasing mortality from hypertension-related diseases with increasing duration of work in both groups of furnace workers may be associated with common furnace work conditions (eg, heat, psychosocial stress, shift work, noise, carbon monoxide).