Mortality from myocardial infarction in relation to exposure to vibration and dust among a cohort of iron-ore miners in Sweden.

Objectives: The aim of this study was to investigate myocardial infarction (MI) mortality in relation to exposure to hand/arm vibration (HAV) and whole body vibration (WBV) as well as exposure to dust among men employed in two Swedish iron-ore mines.

Methods: This study comprised employed men at two iron-ore mines in Sweden who had been employed for at least 1 year from 1923 up to 1996. The causes of death were obtained from the national cause of death register from 1952 to 2001. Myocardial infarction mortality was obtained by linking personal identification numbers to the national cause of death register. Poisson regression was used for risk estimations on exposure-response relation, and analyses were made on the two age groups < or =60 years and >60 years.

Results: Relative risks for MI mortality in relation to exposure were significantly increased for exposure (0/>0) to WBV (RR 1.18, 95% CI 1.06 to 1.31) and dust (RR 1.15, 95% CI 1.02 to 1.31), and the results indicated an exposure-response relation for WBV and dust separately. For 60 years and younger, exposure to HAV (0/>0) (RR 1.34, 95% CI 1.03 to 1.74) and WBV (0/>0) (RR 1.39, 95% CI 1.13 to 1.72) increased the risk of MI mortality. An exposure-response was found for HAV and WBV, as the medium and high exposed categories showed significantly increased risk estimates. None of the exposures significantly increased the risk in the group above 60 years. The increased risk estimates for exposure to WBV remained when adjusting for exposure to dust.

Conclusions: The results for the working age (< or =60 years) group showed significantly increased MI mortality for univariate exposure to HAV, WBV and dust. We found an association between increased mortality from MI and occupational exposure to WBV, and the risk remained after adjustment for dust exposure.