- Correspondence to Dr D C Christiani, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA;
- Received April 6, 2009
- Accepted August 14, 2009
- First published September 21, 2009.
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.