Funding for this research was provided by:
Ministry of Education, Culture, Sports, Science and Technology (#17K19417)
Japan Science and Technology Agency (CREST)
National Center for Global Health and Medicine (29A1020)
Received: 20 November 2019
Accepted: 3 September 2020
First Online: 29 September 2020
Ethics approval and consent to participate
: All participants provided written informed consent. All information regarding participants was rendered anonymous after collection of data and hair samples. The study was reviewed and approved by the Ethics Committee of NCGM (#NCGM-G-00623-02, #NCGM-G-000845-02, #NCGM-G-001766-00), in accordance with the Declaration of Helsinki of the World Medical Association.
: Not applicable.
: The authors declare that they have no competing interests.