Risk of lung cancer associated with residential radon exposure in south-west England: a case-control study

Abstract

Summary Studies of underground miners occupationally exposed to radon have consistently demonstrated an increased risk of lung cancer in both smokers and non-smokers. Radon exposure also occurs elsewhere. especially in houses. and estimates based on the findings for miners suggest that residential radon is responsible for about one in 20 lung cancers in the UK, most being caused in combination with smoking. These calculations depend. however, on several assumptions and more direct evidence on the magnitude of the risk is needed. To obtain such evidence, a case-control study was carried out in south-west England in which 982 subjects with lung cancer and 3185 control subjects were interviewed. In addition, radon concentrations were measured at the addresses at which subjects had lived during the 30-year period ending 5 years before the interview. Lung cancer risk was examined in relation to residential radon concentration after taking into account the length of time that subjects had lived at each address and adjusting for age. sex, smoking status, county of residence and social class. The relative risk of lung cancer increased by 0.08 (95% Cl -0.03, 0.20) per 100 Bq m-3 increase in the observed time-weighted residential radon concentration. When the analysis was restricted to the 484 subjects with lung cancer and the 1637 control subjects with radon measurements available for the entire 30-year period of interest, the corresponding increase was somewhat higher at 0.14 per 100 Bq m-3 (95% Cl 0.01. 0.29), although the difference between this group and the remaining subjects was not statistically significant. When the analysis was repeated taking into account uncertainties in the assessment of radon exposure, the estimated increases in relative risk per 100 Bq m-3 were larger, at 0.12 (95% Cl -0.05. 0.33) when all subjects were included and 0.24 (95% Cl -0.01, 0.56) when limited to subjects with radon measurements available for all 30 years. These results are consistent with those from studies of residential radon carried out in other countries in which data on individual subjects have been collected. The combined evidence suggests that the risk of lung cancer associated with residential radon exposure is about the size that has been postulated on the basis of the studies of miners exposed to radon.

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

“…Radon levels vary markedly by season and measurements obtained will not precisely reflect the true annual average radon concentration. Seasonal correction factors based on previous studies of ambient household radon were, therefore, applied and weighted average concentrations were calculated, assuming 55% of the child's time was spent in the bedroom and 45% in the living area (Wrixon et al, 1988;Darby et al, 1998).…”

“…Radon concentration estimates used were based on measurements of average radon concentration in the home occupied at the time of diagnosis and were seasonally adjusted, using region-specific correction factors. In order to recognise possible dose-response relationships which may not be linear, effects of radon concentrations on childhood cancer risk were investigated for the following pre-defined levels and 200+ Bq m 73 , as used in a UK study of residential radon exposure and lung cancer risk published earlier (Darby et al, 1998). Exposure effects were also estimated by dividing radon concentrations into quintiles and deciles.…”

Residential radon exposure and lung cancer: Variation in risk estimates using alternative exposure scenarios

“…The detailed data collected also allowed for the calculation of risk estimates based on the other general dosimetry models used in many of the previous case -control epidemiologic studies ( Blot et al, 1990;Schoenberg et al, 1990;Pershagen et al, 1992;Pershagen et al, 1994;Alavanja et al, 1994;Alavanja et al, 1999;Letourneau et al, 1994;Auvinen et al, 1996;Ruosteenoja et al, 1996;Darby et al, 1998 ). The risk estimates obtained for the IRLCS were compared with the risk estimates that would have been obtained if the alternative models ( Table 1 ) were used.…”

“…Most of the published case -control studies ( Blot et al, 1990;Schoenberg et al, 1990;Pershagen et al, 1992;Pershagen et al, 1994;Alavanja et al, 1994;Alavanja et al, 1999;Letourneau et al, 1994;Auvinen et al, 1996;Ruosteenoja et al, 1996;Darby et al, 1998;Kreienbrock et al, 2001 ) utilized radon measurements from one or two rooms to characterize the entire domestic exposure and did not attempt to link temporal and spatial home occupancy patterns with multiple radon measurements within a home in order to calculate retrospective cumulative radon exposures for a given time period. Because the study design of the Iowa study ( Field et al, 2000 ) included multiple radon measurements in various areas where the subject spent time and the linkage of these measurements to the subjects' spatial and temporal mobility, the data from the IRLCS provide a unique opportunity to compare various exposure methods while using a common data set.…”

Glass-based radon-exposure assessment and lung cancer risk

“…Further effort is necessary because risk assessment for the general population requires estimating the risk in the actual settings and levels at which radon exposure occurs in dwellings. Accurate exposure assessment is crucial for valid risk estimation but relatively poor assessment of subjects' exposure has likely caused substantial underestimation of risk estimates and loss of statistical power in the residential radon studies ( Lubin et al, 1995;Lagarde et al, 1997;Darby et al, 1998 ). The standard air-based methodology involves measurement of current radon concentrations by alpha -track detectors placed in dwellings previously occupied by a study subject to represent past radon concentrations in these dwellings, and requires identification of the several dwellings where the subject resided.…”