Sequelae of sarin toxicity at one and three years after exposure in Matsumoto, Japan.

In order to clarify the later sequelae of sarin poisoning that occurred in Matsumoto City, Japan, on June 27, 1994, a cohort study was conducted on all persons (2052 Japanese people) inhabiting an area 1050 meters from north to south and 850 meters from east to west with the sarin release site in the center. Respondents numbered 1237 and 836 people when surveys were conducted at one and three years after the sarin incident, respectively. Numbers of persons with symptoms of sarin toxicity were compared between sarin victims and non-victims. Of the respondents, 58 and 46 people had symptoms associated with sarin such as fatigue, asthenia, shoulder stiffness, asthenopia and blurred vision at both points of the survey, respectively. The prevalences were low; some complained of insomnia, had bad dreams, difficulty in smoking, husky voice, slight fever and palpitation. The victims who had symptoms one year after the incident had a lower erythrocyte cholinesterase activity than did those who did not have symptoms at the early stage; such persons lived in an area with a 500 meter long axis north east from the sarin release site. The three-year cohort study clearly showed that the odds ratios of almost all of the symptoms were high in the sarin-exposed group, suggesting a positive relationship between symptoms and grades of exposure to sarin. These results suggest that symptoms reported by many victims of the sarin incident are thought to be sequelae related to sarin exposure.