the basis of a self-reporting questionnaire, including possible exposures to sarin or cyclosarin.

A number of studies have evaluated the possible relationship between exposure to sarin or cyclosarin and neurologic effects in humans. Those outcomes have been the focus of the largest number of studies because of the neurotoxic actions of the chemicals.

Studies of British and US military servicemen who volunteered for an experimental study of the health effects of low-dose exposure to sarin and other chemical-warfare agents did not demonstrate any long-term health effects of exposure to cholinesterase inhibitors. In both the US and British studies, some subjects experienced the acute cholinergic syndrome.

Studies have followed the health effects in people who exhibited the acute cholinergic syndrome after terrorist attacks in Matsumoto and Tokyo, Japan. Three years after the Matsumoto attack, fatigue, headache, and the visual disturbances asthenopia, blurred vision, and narrowing of visual field were more common among people who reported signs of the acute cholinergic syndrome than among those who lived near the sarin release site who did not have signs of the syndrome. An English-language abstract also showed visual-field constriction and abnormal EEG 45 months after the attacks. Some 6–8 months after the Tokyo attack, symptom-free survivors of intermediate to high exposures were impaired on only one of nine neurobehavioral tests, and significant changes on some EEG results and postural sway tests were seen in females. Three years after the Tokyo attack, a dose-effect relationship was found in previously poisoned people on a measure of memory performance (the backward digit span test), and tapping interval for the dominant hand and stabilometry measures with eyes open were affected in exposed people. An uncontrolled study of patients after the Tokyo attack showed ocular effects (tiredness of eyes, dim vision, and difficulty in focusing), tiredness, fatigue, stiff muscles, and headache up to 5 years after the attack.

Studies have been conducted on US troops who were potentially exposed to sarin after munitions demolition at Khamisiyah. There are no reports that any troops had signs of the acute cholinergic syndrome. Studies of veterans showed no differences between troops who were and who were not present at Khamisiyah. However, when they were divided into those who reported that they had or had not witnessed the explosion and were questioned about symptoms present 8 years after the explosion, those who reported witnessing the explosion were more likely to have self-reported changes in memory, difficulty in sleeping, persistent fatigue, and depression.

In addition to the studies of troops potentially exposed to sarin at Khamisiyah, a number of studies have been conducted on cohorts from the Gulf War that