Silica exposure increases the risk of stroke but not myocardial infarction—A retrospective cohort study

INTRODUCTION: Work-related exposure to silica is a global health hazard that causes diseases such as silicosis. Some studies have also reported that silica exposure is linked to elevated cardiovascular disease mortality. However, these diagnoses have not been investigated in detail and there have been few studies on morbidity. The aim of this study is to examine morbidity and mortality from different cardiovascular diseases among silica-exposed Swedish foundry workers. METHODS: Historical and contemporary measurements (1968–2006) of respiratory silica exposure were matched to job categories, individual foundries, and 4 time periods (1968–1979, 1980–1989, 1990–1999, 2000–2006) using a mixed model. Morbidity and mortality data for the studied cohorts were matched against the General Population Registry. Statistical analyses were performed with SPSS and STATA, and the data were stratified by age, gender, and year. RESULTS: Mortality from cardiovascular disease (SMR 1.3; 95% CI 1.2–1.4) and stroke (SMR 1.6, 95% CI 1.2–2.1) was significantly elevated among the studied population. The cohort also exhibited significantly elevated morbidity from stroke (SIR 1.34; 95% CI 1.2–1.5) but not myocardial infarction. The mean age at the time of first morbidity from stroke was 64 years, with 36% of the cases occurring before the age of 60. CONCLUSIONS: Swedish foundry workers exposed to respirable silica exhibit elevated morbidity and mortality from stroke, but not from myocardial infarction. Our results also suggest a relationship between silica exposure and morbidity from stroke at a younger age than the general population.