- Correspondence to Dr Philip Wynn, Occupational Health Service, Durham County Council, County Hall, Durham DH1 4LS, UK;
- Received December 15, 2014
- Revised May 10, 2015
- Accepted June 22, 2015
- First published July 6, 2015.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.