1. Department of Environmental Health Science and Public Health, Akita University Graduate School of Medicine , Akita, Japan
2. Department of Environmental Health, University of Occupational and Environmental Health , Kitakyushu, Japan
3. Division of Ultrastructural Cell Biology, Department of Anatomy, University of Miyazaki , Miyazaki, Japan
4. Department of Preventive Medicine and Public Health, Keio University School of Medicine , Tokyo, Japan
5. Biostatistics Unit, Clinical and Translational Research Center, Keio University Hospital , Tokyo, Japan
6. Department of Public Health, Kitasato University School of Medicine , Sagamihara, Japan