Effects of occupational exposure to respirable quartz dust on acute myocardial infarction

OBJECTIVES: The aim of this study is to investigate the effects of occupational exposure to respirable quartz (RQ) on first acute myocardial infarction (AMI). RQ causes pulmonary diseases like silicosis and has also been linked to cardiovascular diseases. Inflammation is hypothesised as the underlying pathway. METHODS: We performed a 1:3 matched case–control study nested in a cohort of male uranium miners. We included cases (identified from hospital records and validated according to WHO criteria) who had suffered their first AMI while still employed and <65 years of age. Controls were matched by date of birth and Wismut recruitment era. RQ exposure was derived from a job-exposure matrix. We performed a conditional logistic regression adjusted for smoking, metabolic syndrome and baseline erythrocyte sedimentation rate. Subgroups by date of birth and Wismut recruitment era were analysed to minimise the impact of pre-exposures. RESULTS: The study base comprised 292 matched sets. The cumulative exposure ranged from 0 to 38.9 mg/m(3)-years RQ. The adjusted OR of the highest RQ tertile (>14.62 mg/m(3)-years) was 1.27 (95% CI 0.82 to 1.98). However, for miners born after 1928 and hired in the earliest recruitment era (1946–1954), a significantly elevated risk was seen in the highest RQ tertile (OR=6.47 [95% CI 1.33 to 31.5]; 50 matched sets). CONCLUSIONS: An impact of quartz dust on first AMI was observed only in a small subgroup that had virtually no pre-exposure to RQ. Further studies on the basis of complete occupational history are required to substantiate this finding.