CASE-CONTROL STUDY OF CHILDHOOD ACUTE LYMPHOBLASTIC-LEUKEMIA AND RESIDENTIAL RADON EXPOSURE

Background: Several ecologic analyses have shown significant positive associations between mean indoor radon concentrations and risk of leuk emia at all ages (acute myeloid leukemia and chronic lymphocytic leuke mia) and for children (all leukemia, acute myeloid leukemia, and acute lymphoblastic leukemia [ALL]), As part of an age-matched, case-contro l study of childhood ALL in the United States, we investigated the ass ociation between the incidence of ALL in children under age 15 years a nd indoor radon exposure, Methods: Radon detectors were placed in curr ent and previous homes of subjects where they resided for 6 months or longer, Children were included in analyses if radon measurements cover ed 70% or more of the 5-year period prior to diagnosis for case subjec ts (or from birth for case subjects under age 5 years) and the corresp onding reference dates for control subjects, Radon levels could be est imated for 97% of the exposure period for the eligible 505 case subjec ts and 443 control subjects, Results: Mean radon concentration was low er for case subjects (65.4 becquerels per cubic meter [Bqm(-3)]) than for control subjects (79.1 Bqm(-3)), For categories less than 37, 37-7 3, 74-147, and 148 or more Bqm(-3) of radon exposure, relative risks b ased on matched case-control pairs were 1.00, 1.22, 0.82, and 1.02, re spectively, and were similar to results from an unmatched analysis, Th ere was no association between ALL and radon exposure within subgroups defined by categories of age, income, birth order birth weight, sex, type of residence, magnetic field exposure, parental age at the subjec t's birth, parental occupation, or parental smoking habits. Conclusion s: In contrast to prior ecologic studies, the results from this analyt ic study provide no evidence for an association between indoor radon e xposure and childhood ALL.