Risks from Radon: Reconciling Miner andResidential Epidemiology

摘要

Everyone is exposed to radon, an inert radioactive gas that occurs naturally and ispresent everywhere in the atmosphere. The annual dose from radon and its (short-lived) decayproducts is typically about one-half of the dose received by members of the public from allnatural sources of ionizing radiation. Data on exposures and consequent effects have recentlybeen reviewed by the National Council on Radiation Protection and Measurements (NCRP) andthe United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).Studies of underground miners provides a well-established basis for estimating risks fromoccupational exposures to radon and for studying factors that may affect the dose responserelationship such as the reduction of risk (coefficients) with increasing time since exposure.Miners' studies previously formed the basis for estimating risks to people exposed to radon athome, with downward extrapolation from exposures in mines to residential levels of radon.Presently, the risk estimates from residential studies are adequate to estimate radon risks inhomes. Although there are major uncertainties in extrapolating the risks of exposure to radonfrom the miner studies to assessing risks in the home, there is remarkably good agreementbetween the average of risk factors derived from miner studies and those from pooled residentialcase-control studies. There are now over 20 analytical studies of residential radon and lungcancer. These studies typically assess the relative risk from exposure to radon based on estimatesof residential exposure over a period of 25 to 30 years prior to diagnosis of lung cancer. Recentpooled analyses of residential case-control studies support a small but detectable lung cancer riskfrom residential exposure, and this risk increases with increasing concentrations. The excessrelative risk of lung cancer from long-term residential exposure is about the same for bothsmokers and non-smokers; however, because the baseline lung cancer rate for smokers is muchhigher than for non or never smokers, smokers account for nearly 90% of the population riskfrom residential exposure to radon. As described in the paper, an excess relative risk (ERR) of0.12 (95% CI: 0.08-0.2) per 100 Bq M~(-3)(radon gas) can be estimated from combined minerstudies. This compares well with the ERR from pooled residential case-control studies (forrestricted analysis) for Europe of 0.16 (95% CI: 0.05-0.31) [1] and for North America of 0.11(95% CI: 0.0-0.28) [2].