1. Division of Childhood Cancer Epidemiology, Institute for Medical Biostatistics, Epidemiology and Informatics (IMBEI) University Medical Center of the Johannes Gutenberg University Mainz Mainz Germany
2. Danish Cancer Society Research Center Danish Cancer Society Copenhagen Denmark
3. Unit of Epidemiology Institute of Environmental Medicine, Karolinska Institutet Stockholm Sweden
4. Department of Natural Science and Environment Roskilde University Roskilde Denmark
5. Department of Environmental Science Aarhus University Roskilde Denmark