The United Kingdom Childhood Cancer Study of exposure to domestic sources of ionising radiation: 1: radon gas

Abstract

This paper reports the results of the United Kingdom Childhood Cancer Study relating to risks associated with radon concentrations in participants homes at the time of diagnosis of cancer and for at least 6 months before. Results are given for 2226 case and 3773 control homes. No evidence to support an association between higher radon concentrations and risk of any of the childhood cancers was found. Indeed, evidence of decreasing cancer risks with increasing radon concentrations was observed. Adjustment for deprivation score for area of residence made little difference to this trend and similar patterns were evident in all regions and in all diagnostic groups. The study suggests that control houses had more features, such as double glazing and central heating, leading to higher radon levels than case houses. Further, case houses have features more likely to lead to lower radon levels, e.g. living-rooms above ground level. Consequently the case -control differences could have arisen because of differences between houses associated with deprivation that are not adequately allowed for by the deprivation score.

Domestic Radon Exposure and Risk of Childhood Cancer: A Prospective Census-Based Cohort Study

“…Exposure assessment was based on a comprehensive prediction model that was developed and validated using > 40,000 measurements taken throughout Switzerland between 1994 and 2004. Previous case–control studies have reported participation < 55%, and exposure measurements were often limited to subsets of study participants (Cartwright et al 2002; Kaletsch et al 1999; Lubin et al 1998; Maged et al 2000; Steinbuch et al 1999; Stjernfeldt et al 1987). In contrast with ecological studies, we had information on a number of potential individual-level confounders (Laurier et al 2001; Tong et al 2012), although adjusting for these variables did not materially affect hazard ratios, suggesting little or no confounding by these factors although we cannot completely exclude residual confounding due to misclassification in the confounder variables.…”

“…The relationship between radon exposure and childhood leukemia has been addressed in various case–control studies (Cartwright et al 2002; Kaletsch et al 1999; Kendall et al 2013; Lubin et al 1998; Maged et al 2000; Raaschou-Nielsen et al 2008; Steinbuch et al 1999; Stjernfeldt et al 1987) and ecological studies (Alexander et al 1990; Butland et al 1990; Collman et al 1991; Evrard et al 2005, 2006; Foreman et al 1994; Gilman and Knox 1998; Henshaw et al 1990; Lucie 1990; Muirhead et al 1991; Richardson et al 1995; Thorne et al 1996a, 1996b). Most of the ecological studies reported an association between childhood leukemia and estimated domestic radon exposure.…”

“…However, because these were population-level analyses, control for individual-level confounders was not possible. Results of case–control studies have been inconsistent (Laurier et al 2001; Tong et al 2012), with some studies reporting an association (Maged et al 2000; Raaschou-Nielsen et al 2008) and others not (Cartwright et al 2002; Kaletsch et al 1999; Kendall et al 2013; Lubin et al 1998; Steinbuch et al 1999; Stjernfeldt et al 1987). A recent analysis of a Danish case–control study reported evidence that air pollution from road traffic might enhance the association between radon and childhood leukemia (Bräuner et al 2012).…”

“…For central nervous system (CNS) tumors, which are almost all found in the brain (McKinney 2005), only a few ecological (Collman et al 1991; Henshaw et al 1990; Thorne et al 1996b) and case–control studies (Cartwright et al 2002; Kaletsch et al 1999; Kendall et al 2013; Raaschou-Nielsen et al 2008) have been performed, also showing inconsistent results. Ecological studies have suggested an association between domestic radon concentration and CNS tumors (Collman et al 1991; Henshaw et al 1990; Thorne et al 1996b).…”

The Statistical Power of Epidemiological Studies Analyzing the Relationship between Exposure to Ionizing Radiation and Cancer, with Special Reference to Childhood Leukemia and Natural Background Radiation

“…The United Kingdom Childhood Cancer Study (UKCCS), which included radiation measurements on about 2200 cases of childhood cancer of all types (of which about a third are leukemia) and around twice as many controls (9;10) has, by the results of our paper, little power to detect trends with dose – our calculations suggest that it would require at least 9600 leukemia cases to have 80% power of detecting a positive trend at the 1-sided 5% level.…”