Received: 2 December 2019
Accepted: 5 December 2019
First Online: 20 December 2019
Ethics approval and consent to participate
: This study was conducted in accordance with the World Medical Association Declaration of Helsinki. The JECS protocol was approved by the Ministry of the Environment’s Institutional Review Board on Epidemiological Studies (no. 100406001), and approved by the ethics committees of all participating institutions (i.e., Asahikawa Medical College, Chiba University, Doshisha University, Fukushima Medical University, Hokkaido University, Hyogo College of Medicine, Japanese Red Cross Hokkaido College of Nursing, Kochi University, Kumamoto University, Kyoto University, Kyushu University, Nagoya City University, NCCHD, NIES, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka University, Sapporo Medical University, Shinshu University, Tohoku University, Tottori University, University of Occupational and Environmental Health, University of Miyazaki, University of the Ryukyu, University of Toyama, University of Yamanashi, and Yokohama City University). Written informed consent was obtained from all participants. The present study was conducted as a part of JECS and used anonymized data; hence, additional approval from the ethics committee was not required.
: Not applicable.
: The authors declare that they have no competing interests.