Occupational exposure to complex mixtures in the United States military
Maule, Alexis Lynn
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BACKGROUND: Military personnel are occupationally exposed to chemical mixtures at domestic locations and in theater. At military bases, a chemical hazard of concern is JP-8 jet fuel, the largest chemical exposure in the United States Air Force (USAF). We examined blood concentrations of JP-8 constituents as biomarkers of exposure and determined if workday exposure is associated with diminished balance control. Veterans of the 1990-1991 Gulf War (GW) were exposed to mixtures of chemicals in theater and about a third of GW veterans developed GW illness (GWI) on return from deployment. We identified health symptom profiles in the GWI literature and examined longitudinal exposure-symptom relationships in a subset of GW veterans. METHODS: In USAF personnel, personal air, urine, and blood samples were analyzed for components of JP-8. Separate multivariate linear regression analyses were conducted to examine relationships between personal air and post-shift blood volatile organic compounds (VOCs) and between JP-8 exposure and postural sway. Meta-analytic techniques were conducted to determine pooled prevalence and combined odds ratios of symptoms comparing GW and GW-era control veterans. Repeated logistic regression models stratified by sex examined the association of GW exposures and symptoms. RESULTS: Blood VOC concentrations were higher among participants with work-shift JP-8 exposure and breathing zone total hydrocarbons significantly predicted VOC blood levels. Postural sway outcomes were associated with personal variables and task difficulty but not JP-8 exposure. GW veterans had higher odds of reporting all analyzed symptoms compared to GW-era controls, with 20% excess prevalence for fatigue, memory problems, and joint pain. Men had more significant associations between GW exposures and symptoms compared to women. Specific exposures were significantly associated with higher symptom reporting over time. CONCLUSION: In USAF personnel, blood VOC concentrations reflected work-shift exposure to jet fuel, supporting their use as biomarkers of JP-8 exposure. Work-shift exposure to JP-8 did not diminish balance control. Health symptoms evaluated through meta-analysis with the largest summary odds ratios were consistent with the symptom clusters reported in case definitions of GWI. The associations between GW exposure and longitudinal symptom reporting differed between men and women.