1. Department of Public Health Administration, Faculty of Public Health, Khon Kaen University, Khon Kaen, Thailand
2. Department of Environmental Health Science, Faculty of Public Health, Khon Kaen University, Khon Kaen, Thailand
3. Thatphanom Crownprince Hospital, Nakornphanom, Thailand
4. Sirindhorn College of Public Health, Khon Kaen, Thailand
5. Department of Environmental Science, Faculty of Sciences, Khon Kaen University, Khon Kaen, Thailand