1. Department of Environmental and Preventive Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
2. Department of Pharmacology, Jichi Medical University, Shimotsuke, Tochigi, Japan
3. Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
4. Department of Health Science, Asahikawa Medical University, Asahikawa, Hokkaido, Japan