University of North Carolina at Chapel Hill Graduate School
Doi
Abstract
No study to date has examined exposure to individual crude oil chemicals or fine particulate matter (PM2.5) from burning of crude oil/natural gas in relation to coronary heart disease (CHD) among oil spill workers. During the 2010 Deepwater Horizon (DWH) disaster, oil spill response and cleanup (OSRC) workers were exposed to toxic volatile components of crude oil and increased PM2.5 levels from burning of oil/gas.In aim 1, we investigated the association of exposure to total petroleum hydrocarbons (THC) and several crude oil chemicals (benzene, toluene, ethylbenzene, xylene, n-hexane, i.e. BTEX-H) with incident CHD events among 22,655 DWH OSRC workers. In aim 2, we assessed burning-related PM2.5 exposure in relation to CHD risk among 9,091 DWH water workers.Exposures to THC, BTEX-H, and burning-related PM2.5 were estimated via job-exposure matrices that linked air concentration data to self-reported OSRC work histories. We identified incident CHD events that occurred after each worker ended OSRC work from self-report and death certificates. We estimated hazard ratios (HR) and 95% confidence intervals (95%CI) for CHD associated with exposure to BTEX-H/THC (quintiles (Q)) and PM2.5. We applied inverse probability weights to account for bias due to confounding and loss to follow-up. We also assessed the joint effect of the BTEX-H mixture using quantile g-computation.Workers in the highest cumulative exposure category of each crude oil agent had modest increases in CHD risk compared to the referent group (Q1) of that agent (range of HR: 1.14-1.44), although most associations were non-significant. No apparent association was observed for the overall effect of the BTEX-H mixture. Compared to workers not involved in or near the burning (ref), workers with in the highest average PM2.5 exposure category had significantly elevated risk of CHD (HR=2.11, 95%CI: 1.08, 4.12). We also observed a monotonic, but non-significant, trend among workers with higher cumulative PM2.5 exposure (low: HR=1.19, 95%CI: 0.68, 2.08; medium: HR=1.38, 95%CI: 0.88, 2.16; high: HR=1.44, 95%CI: 0.96, 2.14). Higher exposures to volatile components of crude oil and PM2.5 from burning of oil/gas were associated with a modest increase in risk of CHD among oil spill workers.Doctor of Philosoph
