1. Department of Public Health Chung Shan Medical University Taichung 402 Taiwan
2. Oxidative Stress Group, Department of Cell Biology, Microbiology and Molecular Biology University of South Florida Tampa Florida 33620 USA
3. Department of Occupational Safety and Health Chung Shan Medical University Taichung 402 Taiwan
4. Department of Occupational Medicine Chung Shan Medical University Hospital Taichung 402 Taiwan