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], 3.0-24.7; P<.001). Risk of syndrome 2 (''confusion-ataxia'') increased with a scale of advanced adverse effects from pyridostigmine bromide (chi(2) 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 (chi(2) for trend, P<.001) and with advanced adverse effects from pyridostigmine (chi(2) 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.