Proposed revision of the ICRP model for inhaled mercury vapor

A critical review of the literature on the biokinetics of inhaled mercury v apor was performed as part of an accident analysis for the Spallation Neutr on Source to be built at Oak Ridge National Laboratory. It was concluded th at current models for inhaled mercury vapor do not accurately describe the distribution or residence time of mercury deposited in the respiratory trac t. This paper proposes a model that is more consistent with collective info rmation on the fate of inhaled mercury vapor in laboratory animals and huma n subjects. Compared with the model currently recommended by the Internatio nal Commission on Radiological Protection (ICRP), the proposed model predic ts lower deposition in the bronchi and bronchioles, greater deposition in t he alveolar-interstitial region, and a different pattern of absorption to b lood. The proposed model yields substantially reduced estimates of lung dos e and effective dose for most radioisotopes of mercury inhaled as mercury v apor.