Text and Data Mining valid from 2018-08-10
Received: 4 October 2017
Accepted: 6 August 2018
First Online: 10 August 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This study has been approved by the Osaka Rosai Hospital Ethics committee of Japan Organization of Occupational Health and Safety (ID 20130729-5).