Risk of longer-term endocrine and metabolic conditions in the Deepwater Horizon Oil Spill Coast Guard cohort study - five years of follow-up.

Introduction: Long-term endocrine and metabolic health risks associated with oil spill cleanup exposures are largely unknown, despite the endocrine-disrupting potential of crude oil and oil dispersant constituents. We aimed to investigate risks of longer-term endocrine and metabolic conditions among U.S. Coast Guard (USCG) responders to the Deepwater Horizon (DWH) oil spill.

Methods: Our study population included all active duty DWH Oil Spill Coast Guard Cohort members (N = 45,224). Self-reported spill exposures were ascertained from post-deployment surveys. Incident endocrine and metabolic outcomes were defined using International Classification of Diseases (9th Revision) diagnostic codes from military health encounter records up to 5.5 years post-DWH. Using Cox proportional hazards regression, we estimated adjusted hazard ratios (aHR) and 95% confidence intervals (CIs) for various incident endocrine and metabolic diagnoses (2010-2015, and separately during 2010-2012 and 2013-2015).

Results: The mean baseline age was 30 years (~ 77% white, ~ 86% male). Compared to non-responders (n = 39,260), spill responders (n = 5,964) had elevated risks for simple and unspecified goiter (aHR = 2.09, 95% CI: 1.29-3.38) and disorders of lipid metabolism (aHR = 1.09, 95% CI: 1.00-1.18), including its subcategory other and unspecified hyperlipidemia (aHR = 1.10, 95% CI: 1.01-1.21). The dysmetabolic syndrome X risk was elevated only during 2010-2012 (aHR = 2.07, 95% CI: 1.22-3.51). Responders reporting ever (n = 1,068) vs. never (n = 2,424) crude oil inhalation exposure had elevated risks for disorders of lipid metabolism (aHR = 1.24, 95% CI: 1.00-1.53), including its subcategory pure hypercholesterolemia (aHR = 1.71, 95% CI: 1.08-2.72), the overweight, obesity and other hyperalimentation subcategory of unspecified obesity (aHR = 1.52, 95% CI: 1.09-2.13), and abnormal weight gain (aHR = 2.60, 95% CI: 1.04-6.55). Risk estimates for endocrine/metabolic conditions were generally stronger among responders reporting exposure to both crude oil and dispersants (vs. neither) than among responders reporting only oil exposure (vs. neither).

Conclusion: In this large cohort of active duty USCG responders to the DWH disaster, oil spill cleanup exposures were associated with elevated risks for longer-term endocrine and metabolic conditions.