1. Division of Occupational Medicine, Chi-Mei Medical Center, Tainan, Taiwan
2. Department of Occupational Medicine, Chi-Mei Medical Center, Tainan, Taiwan
3. Department of Occupational Medicine, Tainan Municipal Hospital (managed by Show Chwan Medical Care Corporation), Tainan, Taiwan
4. Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan