[1] Kitasato Univ, Dept Occupat Hlth, Grad Sch Med Sci, Kanagawa 2518502, Japan
[2] Kitasato Univ, Dept Occupat Mental Hlth, Grad Sch Med Sci, Kanagawa 2518502, Japan
[3] McGill Univ, Fac Med, Dept Epidemiol Biostat & Occupat Hlth, Montreal, PQ, Canada
[4] Kitasato Univ, Sch Med, Dept Prevent Med & Publ Hlth, Kanagawa, Japan
[5] Showa Univ, Sch Med, Dept Psychiat, Tokyo 142, Japan
[6] Kitasato Univ, Sch Med, Dept Psychiat, Kanagawa, Japan