1. a Department of Occupational Safety and Health, Chang Jung Christian University, Tainan 711, Taiwan
2. e Western Center for Agricultural Health and Safety, University of California, Davis, Calif
3. b Department of Environmental Science and Technology, Royal School of Mines, Imperial College of Science, Technology and Medicine, London SW7 2BP, UK
4. c Department of Epidemiology, School of Public Health, University at Albany, Rensselaer, N.Y.
5. d Department of Epidemiology and Preventive Medicine, University of California, Davis, One Shields Ave., Davis, CA 95616; e-mail: lee@ucdavis.edu
6. f Department of Epidemiology and Preventive Medicine, University of California, Davis, One Shields Ave., Davis, CA 95616