Funding for this research was provided by:
National Institute for Occupational Safety and Health (2460OH008483-13)
Received: 13 December 2017
Accepted: 2 May 2018
First Online: 2 July 2018
Ethics approval and consent to participate
: This study was approved by the University of Kentucky Institutional Review Board protocol number 05–0231-P2J. Since secondary data with no names or addresses were analyzed, consent to participate was waived.
: The authors declare that they have no competing interests.