Radiation doses via inhalation and ingestion under the current and proposed ICRP models
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Date
1989-09-22
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Publisher
AINSE
Abstract
The ICRP are considering lowering the limits for radiation exposure by at least a factor of two. In the Australian sand-mining industry the implications of this decision are that exposure limits will probably be exceeded if the current models for dose estimation are retained. In fact, the current limits are proving difficult to achieve due to the nature of the separation processes involving monazite. If default AMAD values are used and respiration protection factors are not applied using the current model some workers could be considered to be over-exposed.
However, as part of the process of redefinition, the ICRP task group on lung dynamics will also be presenting a revised inhalation exposure model which will appear fairly soon after the new recommendations are released. The biological bases for the new model are discussed as is the likely influence the new lung model will have on dose assessment via inhalation and ingestion, which are the critical pathways in the sand-mining industry.
The current and proposed models are described and the performance of the models is compared for class Y materials in which thorium (the main radiotoxic constituent of monazite) is included. Doses to lymph and bone from translocated inhaled material are considered with reference to clinical data, as are the dose implications of material translocated to the gastrointestinal tract from the lungs or from direct ingestion.
The general effect of the new model is such that by using more realistic deposition and clearance factors the committed effective dose equivalents are reduced by a factor of 5-10 thereby more than compensating for the expected reduction in ICRP exposure limits when applied with the current lung model.
Description
Physical copy held by ANSTO Library at DDC: 571.45/14.
Keywords
Biological models, Dose equivalents, ICRP, Ingestion, Inhalation, Lung Clearance, Mining, Monazites, Occupational exposure, Radiation doses, Radiation protection, Radionuclide kinetics, Recommendations, Thorium
Citation
Twining, J. R. (1989). Radiation doses via inhalation and ingestion under the current and proposed ICRP models. Presentation to the 12th AINSE Radiation Biology Conference, 22-24th September 1989, Lucas Heights, (pp. 13). Lucas Heights, New South Wales : AINSE.