Exposure patterns among Coast Guard responders to the Deepwater Horizon Oil Spill: a latent class analysis

Abstract

Disclaimer: The contents, views or opinions expressed in this presentation are those of the author(s) and do not necessarily reflect official policy or position of Uniformed Services University of the Health Sciences, the Department of Defense (DoD), or the United States Coast Guard. Background: The Deepwater Horizon Oil Spill was an environmental crisis for which multiple groups, including the United States Coast Guard (USCG), provided emergency response services. A cohort of 5,665 USCG oil spill responders completed post-deployment surveys on a number of topics, including oil spill-related exposures and experiences. Methods: This secondary data analysis of survey responses used latent class analysis (LCA) methods to determine the most common exposure patterns in this population of responders. Our LCA model was based on six indicator variables assumed to be independent of each other within latent classes. The indicator variables reflected different aspects of the responders’ experiences: exposure to oil, exposure to engine exhaust fumes, hand sanitizer use, sunblock use, mosquito bites, and level of anxiety. To assess the convergent construct validity of these models, we considered the relationship of the latent classes to indicators not used in the latent class models. We also considered the relationship to the types of missions reported by cohort participants. Results: The data were consistent with four exposure profiles, which we interpreted as “low exposure”, “higher environmental hazard exposure and moderate time outdoors, “moderate environmental hazard exposure and more time outdoors”, and “high exposure to both environmental hazards and time outdoors”. The tests for convergent construct validity supported this interpretation of the latent classes. For example, participants in administrative roles were most likely to be in the low-exposure latent class. Conclusions: The exposure pattern variables resulting from this analysis can help inform future studies of the health impacts of exposure mixtures among oil spill responders.