1. Section of Environment and Radiation; International Agency for Research on Cancer (IARC); 150 Cours Albert Thomas 69372 Lyon France
2. National Cancer Registry; National Health Laboratory Service; 44 De Korte Street, Braamfontein Johannesburg South Africa
3. Department of Pediatric Hematology and Oncology; Hannover Medical School; Carl-Neuberg-Str. 1 30625 Hannover Germany
4. Department of Medicine; Faculty of Health Sciences; University of the Witwatersrand; 7 York Road Parktown 2193 Johannesburg South Africa
5. German Childhood Cancer Registry; Institute for Medical Biostatistics; Epidemiology and Informatics; University Medical Center of the Johannes Gutenberg University Mainz; Obere Zahlbacher Strasse 69 55101 Mainz Germany