[1] Univ Calif San Francisco, Berkeley Ergon Program, Richmond, CA 94804 USA
[2] Univ Calif San Francisco, Sch Nursing, Dept Community Hlth Syst, San Francisco, CA 94143 USA
[3] Univ Calif San Francisco, Dept Med, Div Occupat & Environm Med, San Francisco, CA 94143 USA
[4] Natl Inst Occupat Hlth, Copenhagen, Denmark