The chief scientist reports ... The Scottish case control study of childhood leukaemia and cancer: methodology and environmental measures of exposure.

This major case control study of childhood leukaemia and other cancers aims to identify risk factors and test prior aetiological hypotheses related to exposure to ionising radiation, chemicals, electromagnetic fields and patterns of infections in early life. This paper describes the comprehensive study methodology and demonstrates the efficacy of collecting traditional epidemiological data in conjunction with direct measures of exposure. The data collection phase is incomplete but the preliminary descriptive results indicate that an optimal sample of children will be included in the analyses. This complete and representative data set will provide a unique opportunity for investigating the causes of malignant disease in Scottish children, with the additional weight of exposure measures to complement the body of interview and medically abstracted information.