1. Bangor University School of Medical Sciences Bangor LL57 2DG UK
2. National Research Centre for the Working Environment Copenhagen DK2100 Denmark
3. Heriot Watt University School of Engineering and Physical Sciences Edinburgh EH14 4AS UK
4. Cardiff University European Cancer Stem Cell Research Institute, School of Biosciences Cardiff CF24 4HQ UK
5. Changchun Institute of Applied Chemistry Laboratory of Chemical Biology Changchun 130022 China
6. University of Copenhagen Department of Public Health Copenhagen DK1014 Denmark