A record-based case–control study of natural background radiation and the incidence of childhood leukaemia and other cancers in Great Britain during 1980–2006

Abstract

We conducted a large record-based case-control study testing associations between childhood cancer and natural background radiation. Cases (27 447) born and diagnosed in Great Britain during 1980–2006 and matched cancer-free controls (36 793) were from the National Registry of Childhood Tumours. Radiation exposures were estimated for mother’s residence at the child’s birth from national databases, using the County District mean for gamma-rays, and a predictive map based on domestic measurements grouped by geological boundaries for radon. There was 12% excess relative risk (95% CI 3, 22; 2-sided p=0.01) of childhood leukaemia per millisievert of cumulative red-bone-marrow dose from gamma-radiation; the analogous association for radon was not significant, excess relative risk 3% (95% CI −4, 11; p=0.35). Associations for other childhood cancers were not significant for either exposure. Excess risk was insensitive to adjustment for measures of socio-economic status. The statistically significant leukaemia risk reported in this reasonably-powered study (power ~50%) is consistent with high dose-rate predictions. Substantial bias is unlikely, and we cannot identify mechanisms by which confounding might plausibly account for the association, which we regard as likely to be causal. The study supports the extrapolation of high dose-rate risk models to protracted exposures at natural background exposure levels.

Variation with socioeconomic status of indoor radon levels in Great Britain: The less affluent have less radon

“…Our main data source (Kendall et al, 2015) is an expanded dataset for a large record-based case-control study of naturally occurring radiation and childhood cancer in GB (Kendall et al, 2013b). This expanded dataset includes about 125,000 study subjects.…”

“…For the data of the case-control study the investigators reported that the correlation coefficient between Carstairs Quintile and occupational social class (6 categories) was 0.28 (p<0.001) based on 57 594 study subjects (Kendall et al, 2013a).…”

“…The case-control investigators (Kendall et al, 2013a) remark on the vagueness of some descriptions of occupations on birth records and the difficulty of assigning social class for paternal occupations such as "Engineer" without further information such as employment status and professional qualifications. Both the case-control study (Kendall et al, 2013b) and the UKCCS investigators (UK Childhood Cancer Study Investigators, 2002) preferred the areal index of SES for their main epidemiological analyses.…”

“…The case-control investigators (Kendall et al, 2013a) remark on the vagueness of some descriptions of occupations on birth records and the difficulty of assigning social class for paternal occupations such as "Engineer" without further information such as employment status and professional qualifications. Both the case-control study (Kendall et al, 2013b) and the UKCCS investigators (UK Childhood Cancer Study Investigators, 2002) preferred the areal index of SES for their main epidemiological analyses. The case-control study investigators remarked that, compared to national statistics, their study participants had a relative deficit of social class 2 with rather higher proportions in lower social classes -presumably more affluent individuals being wrongly assigned to lower social classes.…”

“…Raaschou-Nielsen reviewed studies of indoor radon (Raaschou-Nielsen, 2008) and childhood leukemia and since that time other reports have been published, e.g. by Hauri et al (Hauri et al, 2013) and by Kendall et al (Kendall et al, 2013b). However many such studies appear underpowered and no clear picture has yet emerged.…”