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The sarin gas attack in the Tokyo subway system is reviewed from a clinical toxicology perspective. Based on the lessons learned from this attack, the following areas should be addressed on a global scale. First, an adequate supply of protective equipment is required, including level B protective equipment with a pressure demand breathing apparatus. In addition, a system should be established that enables a possible cause to be determined based on symptoms, physical findings, general laboratory tests, and a simple qualitative analysis for poisonous substances. If an antidote is needed, the system should enable it to be administered to the victims as quickly as possible. Preparation for a large-scale chemical attack by terrorists requires the prior establishment of a detailed decontamination plan that utilizes not only mass decontamination facilities but also public facilities in the area. A system should be established for summarizing, evaluating, and disseminating information on poisonous substances. Finally, a large-scale scientific investigation of the Tokyo sarin attack should be conducted to examine its long-term and subclinical effects and the effects of exposure to asymptomatic low levels of sarin.

The Tokyo subway sarin attack was the second documented incident of nerve gas poisoning in Japan. The St. Luke's International Hospital received 640 patients on the day of the attack. Reduction in plasma cholinesterase (ChE) activity was generally associated with the severity of acute signs of toxicity. With time and treatment, the value rose quickly. To evaluate possible residual signs of symptoms 1 year after the attack, we sent questionnaires to the victims; of 303 respondents, 45% still had some symptoms including eye problems, easy fatigability, headache, and fear. Therefore, we conducted a study in collaboration with investigators at the Tokyo University Department of Public Health to evaluate possible long-term neuropsychological sequelae. The findings suggest the need to closely follow such patients for possible persistent functional changes.