Funding for this research was provided by:
UOEH Research Grant for Promotion of Occupational Health (915)
Received: 24 March 2019
Accepted: 16 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: This study on humans was conducted according to guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the Medical Research, University of Occupational and Environmental Health, Japan (approval number H29–182, October 10, 2017). Informed consent was waived because of the retrospective nature of the study. This study on animals was approved by the Ethics Committee of Animal Care and Experimentation, University of Occupational and Environmental Health, Japan (approval number AE-14-019, December 15, 2014) and was performed in accordance with the National Institutes of Health guidelines.
: Not applicable.
: The authors declare that they have no competing interests.