Exposure to Spill-related Chemicals and Incident Myocardial Infarction among Deepwater Horizon Response and Cleanup Workers

Abstract

BACKGROUND AND AIM: No study has examined exposure to individual oil spill-related chemicals in relation to cardiovascular outcomes among oil spill workers. During the 2010 {Deepwater Horizon} ({DWH}) disaster, response and cleanup workers were potentially exposed to toxic volatile components of crude oil. We investigated the association of several spill-related chemicals (benzene, toluene, ethylbenzene, xylene, n-hexane, i.e. BTEX-H) and total hydrocarbons (THC) with incident non-fatal myocardial infarction (MI) among these workers. METHODS: We examined data from {DWH} oil spill workers enrolled in the prospective GuLF Study. Cumulative exposures to BTEX-H and THC across the cleanup period were estimated via a job-exposure matrix that linked air measurement data with detailed work histories. Physician-diagnosed non-fatal MIs that occurred after the start of cleanup were self-reported at enrollment and in two follow-up interviews. We estimated hazard ratios and 95% confidence intervals (95%CI) for the associations of each exposure (quartiles (Q)) with incident MI. We applied inverse probability weights to account for confounding and potential non-response bias in the follow-up interviews. RESULTS:Among 22,766 workers without MI diagnoses before the cleanup, 443 reported an incident MI up to 10.9 years after the spill. Compared to the referent group (i.e. lowest quartile (Q1)), workers in the higher quartiles of benzene (Q4 vs. Q1: 1.46, 95%CI: 1.04, 2.06), ethylbenzene (Q4 vs. Q1: 1.50, 95%CI: 1.07, 2.10), n-hexane (Q4 vs. Q1: 1.52, 95%CI: 1.08, 2.12), and THC (Q4 vs. Q1: 1.46, 95%CI: 1.05, 2.03) had elevated hazards of MI. Associations were stronger among workers with lower education (≤high school) or with lower body mass index (30 kg/m²). CONCLUSIONS:Exposure to volatile components of the crude oil, notably benzene, ethylbenzene, and n-hexane, was associated with higher risk of MI among oil spill workers. Planned mixtures analysis will help identify the contribution of each of these chemicals. KEYWORDS: myocardial infarction, occupational epidemiology, petroleum hydrocarbons, oil spills