1. Department of Environmental Health, School of Public Health; China Medical University; Shenyang 110122 China
2. Department of Health Sciences; Oita University of Nursing and Health Sciences; Oita 870-1201 Japan
3. Center for Health and Environmental Risk Research; National Institute for Environmental Studies; 16-2 Onogawa, Tsukuba Ibaraki 305-8506 Japan
4. Department of Immunology and Parasitology, School of Medicine; University of Occupational and Environmental Health; Fukuoka 807-8555 Japan
5. Environmental Health Division, Department of Environmental Engineering, Graduate School of Engineering; Kyoto University; Kyoto 615-8530 Japan
6. Department of Environmental Toxicology; University of California; Davis CA 95616 USA