1. Department of Pediatrics, Obihiro-Kosei Hospital, Obihiro, Japan
2. Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
3. Department of Pediatrics, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
4. Department of Pediatrics, Hiroshima City North Medical Center Asa Citizens Hospital, Hiroshima, Japan
5. Center for Environmental and Health Sciences, Hokkaido University, Sapporo, Japan