1. Department of Preventive Medicine, Seoul National University, College of Medicine, Seoul, Korea.
2. Department of Occupational and Environmental Medicine, Inha University Hospital, Inha University, Incheon, Korea.
3. Department of Public Health and Community Medicine, Seoul Metropolitan Government–Seoul National University Boramae Medical Center, Seoul, Korea.
4. Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul, Korea.