[1] NIH, Occupat & Environm Epidemiol Branch, Div Canc Epidemiol & Genet, Dept Hlth & Human Serv, Bethesda, MD 20892 USA
[2] Univ Calif Berkeley, Sch Publ Hlth, Div Environm Hlth Sci, Berkeley, CA 94720 USA
[3] Univ Utrecht, Inst Risk Assessment Sci, Div Environm Epidemiol, NL-3508 Utrecht, Netherlands