1. School of Community and Environmental Health, College of Health Sciences, Old Dominion University, 4608 Hampton Boulevard, Norfolk, VA 23509, USA
2. Department of Mathematics and Statistics, College of Sciences, Old Dominion University, 4608 Hampton Boulevard, Norfolk, VA 23509, USA
3. Institute of Labor, Occupational Safety and Health, Ministry of Labor, No. 99, Lane 407, Hengke Rd., Sijhih District, New Taipei City 22143, Taiwan
4. School of Public Health, National Defense Medical Center, No.161, Sec. 6, Minquan E. Rd., Neihu Dist., Taipei 11490, Taiwan
5. Center for Environmental Toxin and Emerging Contaminant Research, Cheng Shiu University, No. 840, Chengqing Rd., Niaosong District, Kaohsiung City 833, Taiwan