Dose to the adult lung from inhalation of radon-222 and its progeny

The authors derived realistic dose conversion factors (DCF's) for estimating the dose to the lung from inhalation of radon-222 and its short-lived decay products. Derivations of DCF's that are normalized to a working level (WL) base have been found in the literature. Implicit in such derivations is the erroneous assumption of the equivalence of the decay products of radon-222 in their potential for delivering a given dose to the critical basal cells of the segmental bronchi. As a result, any dose calculated by using a DCF normalized to WL can be in significant error, depending on the correlation between the degree of decay product equilibrium assumed in the DCF derivation and that in the atmosphere for which the dose is evaluated. Likewise, significant error can result from the use of a DCF normalized to an atmospheric radon-222 concentration because an assumption concerning decay product equilibrium is made in deriving the DCF. Therefore, the authors derived DCF's on a daughter-by-daughter basis for estimating doses from inhalation of the short-lived products (RaA, RaB, and RaC) of radon-222. Because of the design of the methodology, these DCF's will translate near or slightly above the median dose for a large group of adults exposed to a given atmosphere. Uncertainties are discussed. (author)