Ischemic Heart Disease Mortality and Diesel Exhaust and Respirable Dust Exposure in the Diesel Exhaust in Miners Study

Abstract

Diesel exhaust is a suggested risk factor for ischemic heart disease (IHD), but evidence from cohorts using quantitative exposure metrics is limited. We examined the impact of respirable elemental carbon (REC), a key surrogate for diesel exhaust, and respirable dust (RD) on IHD mortality, using data from the Diesel Exhaust in Miners Study (DEMS). In a cohort of male workers followed from 1948-1968 until 1997, we fitted Cox proportional hazards models to estimate hazard ratios (HR) of IHD mortality for cumulative and average intensity of exposure to REC and RD. Segmented linear regression models allowed for non-monotonicity. HRs for cumulative and average REC declined relative to the lowest exposure category before increasing to 0.79 and 1.25, respectively, in the highest category. Relative to the category containing the segmented regression change-points, HRs for the highest category were 1.69 and 1.54 for cumulative and average REC, respectively. HRs for RD increased across the full exposure range to 1.33 and 2.69 for cumulative and average RD, respectively. Tests for trend were statistically significant for cumulative REC (above the change-point) and for average RD. Our findings suggest excess risk of IHD mortality in relation to increased exposure to REC and RD.