1. Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02138, USA
2. Division of Occupational Medicine, Cambridge Health Alliance/Harvard Medical School, Cambridge, MA 02139, USA
3. Institute of Health and Welfare Policy, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
4. Occupational Medicine, Department of Family Medicine, National Yang Ming Chiao Tung University Hospital, Yilan 260, Taiwan
5. Faculty of Social Sciences Health Sciences (Epidemiology), Tampere University, 33100 Tampere, Finland