[Show abstract][Hide abstract] ABSTRACT: 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.
Traffic exhaust in the air enhances the risk association between radon and childhood leukemia.
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.
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.
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.
Cancer Causes and Control 11/2010; 21(11):1961-4. DOI:10.1007/s10552-010-9608-4 · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Higher incidence rates of childhood cancer and particularly leukemia have been observed in regions with higher radon levels, but case-control studies have given inconsistent results. We tested the hypothesis that domestic radon exposure increases the risk for childhood cancer.
We identified 2400 incident cases of leukemia, central nervous system tumor, and malignant lymphoma diagnosed in children between 1968 and 1994 in the Danish Cancer Registry. Control children (n = 6697) were selected from the Danish Central Population Registry. Radon levels in residences of children and the cumulated exposure of each child were calculated as the product of exposure level and time, for each address occupied during childhood.
Cumulative radon exposure was associated with risk for acute lymphoblastic leukemia (ALL), with rate ratios of 1.21 (95% confidence interval = 0.98-1.49) for levels of 0.26 to 0.89 x 10(3) Bq/m3-years and 1.63 (1.05-2.53) for exposure to >0.89 x 10(3) Bq/m3-years, when compared with <0.26 x 10(3) Bq/m3-years. A linear dose-response analysis showed a 56% increase in the rate of ALL per 10(3) Bq/m3-years increase in exposure. The association with ALL persisted in sensitivity analyses and after adjustment for potential confounders. No association was found with the other types of childhood cancer.
This study suggests that domestic radon exposure increases the risk for ALL during childhood but not for other childhood cancers.
[Show abstract][Hide abstract] ABSTRACT: A linear regression model has been developed for the prediction of indoor (222)Rn in Danish houses. The model provides proxy radon concentrations for about 21,000 houses in a Danish case-control study on the possible association between residential radon and childhood cancer (primarily leukaemia). The model was calibrated against radon measurements in 3116 houses. An independent dataset with 788 house measurements was used for model performance assessment. The model includes nine explanatory variables, of which the most important ones are house type and geology. All explanatory variables are available from central databases. The model was fitted to log-transformed radon concentrations and it has an R(2) of 40%. The uncertainty associated with individual predictions of (untransformed) radon concentrations is about a factor of 2.0 (one standard deviation). The comparison with the independent test data shows that the model makes sound predictions and that errors of radon predictions are only weakly correlated with the estimates themselves (R(2) = 10%).