Fine particulate matter and incident coronary heart disease events up to 10 years of follow-up among Deepwater Horizon oil spill workers

Background: During the 2010 Deepwater Horizon (DWH) disaster, in-situ burning and flaring were conducted to remove oil from the water. Workers near combustion sites were potentially exposed to burning-related fine particulate matter (PM_2.5). Exposure to PM_2.5 has been linked to increased risk of coronary heart disease (CHD), but no study has examined the relationship among oil spill workers.

Objectives: To investigate the association between estimated PM_2.5 from burning/flaring of oil/gas and CHD risk among the DWH oil spill workers.

Methods: We included workers who participated in response and cleanup activities on the water during the DWH disaster (N = 9091). PM_2.5 exposures were estimated using a job-exposure matrix that linked modelled PM_2.5 concentrations to detailed DWH spill work histories provided by participants. We ascertained CHD events as the first self-reported physician-diagnosed CHD or a fatal CHD event that occurred after each worker’s last day of burning exposure. We estimated hazard ratios (HR) and 95% confidence intervals (95%CI) for the associations between categories of average or cumulative daily maximum PM_2.5 exposure (versus a referent category of water workers not near controlled burning) and subsequent CHD. We assessed exposure-response trends by examining continuous exposure parameters in models.

Results: We observed increased CHD hazard among workers with higher levels of average daily maximum exposure (low vs. referent: HR = 1.26, 95% CI: 0.93, 1.70; high vs. referent: HR = 2.11, 95% CI: 1.08, 4.12; per 10 μg/m³ increase: HR = 1.10, 95% CI: 1.02, 1.19). We also observed suggestively elevated HRs among workers with higher cumulative daily maximum exposure (low vs. referent: HR = 1.19, 95% CI: 0.68, 2.08; medium vs. referent: HR = 1.38, 95% CI: 0.88, 2.16; high vs. referent: HR = 1.44, 95% CI: 0.96, 2.14; per 100 μg/m³-d increase: HR = 1.03, 95% CI: 1.00, 1.05).

Conclusions: Among oil spill workers, exposure to PM_2.5 from flaring/burning of oil/gas was associated with increased risk of CHD.