There is a substantial world-wide industry involving the mining and milling of materials which contain uranium or thorium with their radioactive decay products. During these processes an inhalation hazard can arise if dusts are formed. For many years the appropriate ICRP advice for assessing the doses from these dusts was based on the model of the respiratory system and the element-specific biokinetic models recommended in ICRP Publication 30. Recently, ICRP has published a new model of the respiratory tract and also new physiologically based biokinetic models for some elements which have naturally occurring radioactive isotopes. This paper gives a brief account of the ores and sands involved and explores the implications for dose coefficients of the new ICRP models. It is concluded that, for insoluble ores, the new models generally lead to lower doses than those predicted under the ICRP 30 scheme. A substantial factor in reducing doses is the ICRP recommendation that, in the absence of specific information, the default aerosol size distribution for occupational exposures should be taken to be 5 mu m AMAD rather than 1 mu m AMAD as previously.
Copyright 2007 Elsevier B.V., All rights reserved.