Effects of sarin on the nervous system of subway workers seven years after the Tokyo subway sarin attack

This study was designed to assess the aftereffects of sarin exposure on the nervous system in victims of the Tokyo Subway Sarin Attack, which occurred on 20 March, 1995. We performed a similar study 3 yr after the disaster. This time, we newly enrolled 36 staff of the Teito Rapid Transit Authority (Tokyo Eidan subway) to assess the 7 yr after effects on the nervous system, and merged previous data including unpublished data to enhance statistical power. New subjects consisted of 23 male exposed subjects and 13 referent subjects matched for age and working types. Neurobehavioral tests for psychomotor function and memory, stabilometry, and Benton visual retention test were performed. As reported previously, the exposed group performed significantly less well in the psychomotor function test (tapping) than the referent group (117.8 +/- 1.2 vs. 105.6 +/- 1.2 msec). Using merged data, this phenomenon was also observed in a dose-dependent manner and the exposed group performed significantly less well in the backward digit span test (4.47 +/- 1.17 vs. 5.11 +/- 1.65 digits). These results indicate that chronic decline of psychomotor function and memory function still exist 7 yr after the sarin exposure.