1. GSF–National Research Center for Environment and Health, Neuherberg, Germany
2. Limburg University Center, Diepenbeek, Belgium
3. Friedrich-Alexander-University of Erlangen-Nuremberg, Germany
4. National Research Center for Environment and Health, Neuherberg, Germany
5. University of Berne, Switzerland
6. University of Jyv‰skyl‰, Finland
7. University of Illinois at Urbana-Champaign (em.), United States of America
8. University of Barcelona, Spain
9. Netherlands Institute of Health Services Research, Utrecht, The Netherlands