Self-reported exposure to neurotoxic chemical combinations in the Gulf War: A cross-sectional epidemiologic study

Objective. - To identify risk factors of factor analysis-derived Gulf War-related syndromes. Design. - A cross-sectional survey. Participants. - A total of 249 Gulf War veterans from the Twenty-fourth Reserve Naval Mobile Construction Battalion. Data Collection. - Participants completed standardized booklets measuring self-reported wartime exposures and present symptoms. Main Outcome Measures. - Associations of factor analysis-derived syndromes with risk factors for chemical interactions that inhibit butyrylcholinesterase and neuropathy target esterase. Results. - Risk of syndrome 1 ('impaired cognition') was greater in veterans who reported wearing flea collars during the war (5 of 20, 25%) than in those who never wore them (7 of 229, 3%; relative risk [RR], 8.7; 95% confidence interval [CI], 3.024.7; P<.001). Risk of syndrome 2 ('confusion-ataxia') increased with a scale of advanced adverse effects from pyridostigmine bromide (χ² for trend, P<.001), was greater among veterans who believed they had been involved in chemical weapons exposure (18 of 108, 17%) than in those who did not (3 of 141,2%; RR, 7.8; 95% CI, 2.3-25.9; P<.001), and was increased in veterans who had been in a sector of far northeastern Saudi Arabia on the fourth day of the air war (6 of 21,29%) than in those who had not been (15 of 228, 7%; RR, 4.3; 95% CI, 1.9-10.0; P=.004). Effects of perceived chemical weapons exposure and advanced adverse effects from pyridostigmine were synergistic (Rothman S, 5.3; 95% CI, 1.04-26.7). Risk of syndrome 3 ('arthro- myo-neuropathy') increased with an index of frequency and amount of government-issued insect repellent containing 75% DEET (N,N-diethyl-m- toluamide) in ethanol applied during the war (χ² for trend, P<.001) and with advanced adverse effects from pyridostigmine (χ² for trend, P<.001). Conclusion. - Some Gulf War veterans may have delayed, chronic neurotoxic syndromes from wartime exposure to combinations of chemicals that inhibit butyrylcholinesterase and neuropathy target esterase.