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Article History

Received: 6 June 2018

Accepted: 4 February 2019

First Online: 20 February 2019

Ethics approval and consent to participate

: JECS was approved by the institutional review board on epidemiological studies of the Ministry of the Environment and the ethics committees of all the participating institutions (i.e., NIES, NCCHD, Hokkaido University, Sapporo Medical University, Asahikawa Medical College, Japanese Red Cross Hokkaido College of Nursing, Tohoku University, Fukushima Medical University, Chiba University, Yokohama City University, University of Yamanashi, Shinshu University, University of Toyama, Nagoya City University, Kyoto University, Doshisha University, Osaka University, Osaka Medical Center and Research Institute for Maternal and Child Health, Hyogo College of Medicine, Tottori University, Kochi University, University of Occupational and Environmental Health, Kyushu University, Kumamoto University, University of Miyazaki, and University of the Ryukyus). JECS is being conducted in accordance with the Declaration of Helsinki and other relevant regulations in the country. 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.

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