Associations between BTEX-H/THC and neurological symptoms among Deepwater Horizon oil spill workers

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Background and Aim Hydrocarbons are considered to be neurotoxic. However, less is known about health effects of generally lower exposures during oil spill response and clean-up. The Gulf Long-Term Follow-up (GuLF) Study follows individuals who were either involved in cleanup efforts ("workers”) or were trained but not hired ("non-workers”) following the 2010 Deepwater Horizon disaster. We studied the association of neurological symptoms with exposure to benzene, toluene, ethylbenzene, xylenes, and hexane (BTEX-H) individually and as a mixture among 23,641 workers. Methods At enrollment, participants self-reported frequency of neurological symptoms including dizziness, nausea, sweating, heart palpitations, fatigue, insomnia, migraines, tingling, numbness, blurred vision, stumbling, and seizures in the preceding 30 days. Cumulative inhalation exposure to BTEX-H chemicals and total hydrocarbons (THC) was estimated using a job exposure matrix linking air measurement data to detailed self-reported cleanup work histories. We calculated adjusted prevalence ratios (PR) and 95% confidence intervals (CI) for the association between quartiles of exposure and neurological symptoms reported all or most of the time using multivariable log-binomial regression. Quantile G-computation was used to estimate the per-quartile increase in joint effects of the BTEX-H mixture on neurological symptoms. Results 31% of participants reported experiencing at least one, and 21% reported 2 or more, neurological symptoms within the last 30 days. Exposure to THC was associated with increased risk of two or more neurological symptoms (Q4 vs. Q1 PR=1.57 (95% CI:1.45, 1.70)), with similar results observed for the individual BTEX-H chemicals. A quartile increase in exposure to the BTEX-H mixture was associated with an increased risk of reporting two or more neurological symptoms (PR=1.18, (95% CI: 1.15, 1.21)). Conclusions Exposure to oil spill-related THC and BTEX-H was associated with increased prevalence of neurological symptoms among cleanup workers. Keywords: Occupational epidemiology, crude oil, BTEX, neurological symptoms, disaster