Published: 1994
Total Pages: 25
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This chapter reviews recent developments in modeling doses received by lung tissues, with particular emphasis on application of ICRPs̀ new dosimetric model of the respiratory tract for extrapolating to other environments the established risks from exposure to radon progeny in underground mines. Factors discussed include: (1) the influence of physical characteristics of radon progeny aerosols on dose per unit exposure, e.g., the unattached fraction, and the activity-size distributions of clustered and attached progeny; (2) the dependence of dose on breathing rate, and on the exposed subject (man, woman or child); (3) the variability of dose per unit exposure in a home when exposure is expressed in terms of potential? energy or radon gas concentration; (4) the comparative dosimetry of thoron progeny; and (5) the effects of air-cleaning on lung dose. Also discussed is the apparent discrepancy between lung cancer risk estimates derived purely from dosimetry and the lung cancer incidence observed in the epidemiological studies of radon-exposed underground miners. Application of ICRPs̀ recommended risk factors appears to overestimate radon lung-cancer risk for miners by a factor of three. Ǹ̀ormalization ̀̀of the calculated effective dose is therefore needed, at least for? dose from radon and thoron progeny, in order to obtain a realistic estimate of lung cancer risk.