The rapid worldwide increase in mobile phone use in adolescents and, more recently, children has generated considerable interest in the possible health effects of exposure to radio frequency (RF) fields. The current project aims to assess the potential carcinogenic effects of childhood and adolescent exposure to RF and ELF from mobile telephones on tumours of the central nervous system. The study will include approximately 1,000 cases of malignant and benign brain tumours aged 10 to 24 years and their respective controls from 15 countries (7 of which have funding under this contract). The project will build upon the methodological experience (both in terms of exposure assessment and epidemiological design) collected within the INTERPHONE study. Particular attention will be paid to issues of: potential selection bias related to the very low response rates of population-based controls – by selecting hospitalized controls with specific diagnoses, representative of the general population and unrelated to mobile phone use –; and potential recall errors – by validating questionnaire responses with the help of network operators and repeat questionnaires. Improved exposure indices for RF will be derived taking into account spatial distribution of energy in the brain at different ages; ELF from the phones will also be considered, as well as other important sources of EMF in the general environment of young people. The proposed age range is the most cost efficient to answer the question (because of latency) of brain cancer risk from exposure in childhood and adolescence. The timing of the project is optimal (2010-2014) because of the increasing prevalence of heavy use among adolescents and, in the last 5-10 years, children, without hands-free kits, particularly in Southern European countries and Israel.