1. Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia , 43400 UPM Serdang , Selangor , Malaysia
2. Department of Occupational Health and Safety, Faculty of Public Health, Universitas Airlangga , 60115 Surabaya , East Java , Indonesia
3. Department of Biomedical Science , Faculty of Medicine and Health Sciences , Universiti Putra Malaysia , 43400 UPM Serdang , Selangor , Malaysia