Lung cancer risk and effective dose coefficients for radon: UNSCEAR review and ICRP conclusions.

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has provided a detailed and authoritative update of its reviews of the epidemiology and dosimetry of radon and progeny. Lifetime risk of lung cancer calculated using data for several miner cohorts were 2.4 - 7.5 x 10-4 per Working Level Month (WLM) of radon-222 progeny exposure for a mixed male / female population and 3.0 - 9.6 x 10-4 per WLM for a male population. Dosimetric models gave mean values of effective dose coefficients from radon-222 progeny of 12 mSv per WLM for mines, 16 mSv per WLM for indoor workplaces and 11 mSv per WLM for homes. The lifetime risk coefficient used by the International Commission on Radiological Protection (ICRP) is 5 x 10-4 per WLM and it has recently recommended an effective dose coefficient for radon-222 and progeny of 3 mSv per mJ h m-3 (about 10 mSv per WLM) for most circumstances of exposure. The ICRP risk and dose coefficients are supported by the UNSCEAR review and provide a clear and firm basis for current international advice and standards for protection from radon. UNSCEAR will continue to use a lower value of effective dose coefficient of 5.7 mSv per WLM for assessments of population exposures.