title: Is there any interaction between domestic radon exposure and air pollution from traffic in relation to childhood leukemia risk?
abstract: BACKGROUND
  In a recent population-based case-control study using 2,400 cases of childhood cancer, we found a statistically significant association between residential radon and acute lymphoblastic leukemia risk.
  
  
  OBJECTIVE
  Traffic exhaust in the air enhances the risk association between radon and childhood leukemia.
  
  
  METHODS
  We included 985 cases of childhood leukemia and 1,969 control children. We used validated models to calculate residential radon and street NO(x) concentrations for each home. Conditional logistic regression analyses were used to analyze the effect of radon on childhood leukemia risk within different strata of air pollution and traffic density.
  
  
  RESULTS
  The relative risk for childhood leukemia in association with a 10(3) Bq/m(3)-years increase in radon was 1.77 (1.11, 2.82) among those exposed to high levels of NO(x) and 1.23 (0.79, 1.91) for those exposed to low levels of NO(x) (p(interaction,) 0.17). Analyses for different morphological subtypes of leukemia and within different strata of traffic density showed a non-significant pattern of stronger associations between radon and childhood leukemia within strata of higher traffic density at the street address.
  
  
  CONCLUSIONS
  Air pollution from traffic may enhance the effect of radon on the risk of childhood leukemia. The observed tendency may also be attributed to chance.
authors.affiliation: Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, 2100 Copenhagen, Denmark. elvira@cancer.dk
authors.forename: Elvira Vaclavik
authors.initials: EV
authors.lastname: Bräuner
authors.forename: Claus E
authors.initials: CE
authors.lastname: Andersen
authors.forename: Helle P
authors.initials: HP
authors.lastname: Andersen
authors.forename: Peter
authors.initials: P
authors.lastname: Gravesen
authors.forename: Morten
authors.initials: M
authors.lastname: Lind
authors.forename: Kaare
authors.initials: K
authors.lastname: Ulbak
authors.forename: Ole
authors.initials: O
authors.lastname: Hertel
authors.forename: Joachim
authors.initials: J
authors.lastname: Schüz
authors.forename: Ole
authors.initials: O
authors.lastname: Raaschou-Nielsen
mesh_terms: D000397:Air Pollution; D016022:Case-Control Studies; D002648:Child; D003718:Denmark / Q000453:epidemiology; D006798:Housing; D006801:Humans; D007938:Leukemia / Q000453:epidemiology* / Q000209:etiology; D016015:Logistic Models; D009369:Neoplasms / Q000453:epidemiology / Q000209:etiology; D011886:Radon / Q000032:analysis* / Q000633:toxicity*; D012306:Risk; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D001335:Vehicle Emissions; D011886:Radon