Residential exposure to solar ultraviolet radiation and incidence of childhood hematological malignancies in France

Purpose: Few studies have investigated the relationship between solar ultraviolet radiation (UV) and childhood hematological malignancies (CHM). This study addresses the associations between residential UV exposure at diagnosis and the incidence of types and subtypes of CHM, by age and gender, in France, over a long period, on the fine scale of the 36,326 Communes that constitute mainland France. Methods: The 9,082 cases of acute leukemia and 3,563 cases of lymphoma diagnosed before the age of 15 years from 1990 to 2009 were provided by the French National Registry of Childhood Hematological Malignancies. The incidence of CHM was calculated by Commune, year, age and gender and expressed as the standardized incidence ratio (SIR). UV data from 1988 to 2007 were extracted from the EUROSUN database. Results: The annual daily average UV exposure of the children ranged from 85.5 to 137.8 J/cm². For each additional 25 J/cm², there was a significant increase in precursor B-cell acute lymphoblastic leukemia (PBC-ALL) in children aged less than 5 years (SIR 1.18; 95 % CI 1.10–1.27). Further analysis of PBC-ALL in the young children suggested a better fit of models with a threshold, with the risk increasing above 100 J/cm², for which the SIR was 1.24 (95 % CI 1.14–1.36) for a 25 J/cm² increase. The results remained stable in analyses stratifying by deprivation index or degree of urbanization of the Communes. Conclusion: The study suggests that higher residential UV exposure may be positively associated with a higher incidence of PBC-ALL in early childhood.