1. Department of Occupational Safety and Health, Chung Shan Medical University, Taichung 402, Taiwan
2. Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan
3. Laboratory of Genetic Ecotoxicology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague, Czech Republic
4. Centre for Radiation Protection Research, Department of Molecular Bioscience, Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
5. School of Community and Environmental Health, College of Health Sciences, Old Dominion University, Norfolk, VA 23529, USA
6. Department of Public Health, Chung Shan Medical University, Taichung 402, Taiwan