title: Assessing the reliability of dose coefficients for ingestion and inhalation of 226Ra and 90Sr by members of the public.
abstract: Assessments of risk to a population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficient, E(50), used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the risk is important for informing judgements on reliability. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioisotopes of the alkaline earth metals, (90)Sr and (226)Ra, by members of the UK public. The study derives uncertainties in biokinetic model parameter values to calculate the distributions of the effective dose per unit intake using the ICRP Publication 60 formalism. The distributions are used to infer the uncertainty on the mean effective dose per unit intake to inform the derivation of uncertainty factors (UF) for the appropriate ICRP Publication 72 dose coefficients. Here, a UF indicates a 95 % probability that the best estimate of risk per unit intake is within a factor, UF, of the nominal risk associated with the appropriate ICRP dose coefficient, E(50), with respect to uncertainties in the biokinetic model parameter values. Ingestion: it is assumed that exposure occurs through the ingestion of radionuclides present in food and water. The results for both radionuclides suggest a UF of within 3 for all age groups, with median values close to the ICRP values. Inhalation: it is assumed that environmental exposure to radium occurs primarily due to insoluble forms present in fly ash discharged from coal-fired power stations; for strontium, exposure is assumed to occur due to residual aerosols produced as a result of atmospheric nuclear testing and nuclear reactor accidents. The results suggest a UF of around 3 and 6 for inhalation of (90)Sr and (226)Ra, respectively, by members of the public.
authors.affiliation: Department of Toxicology, Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot OX11 0RQ, UK.
authors.forename: M
authors.initials: M
authors.lastname: Puncher
mesh_terms: D000328:Adult; D002648:Child; D004064:Digestive System / Q000528:radiation effects*; D004435:Eating; D005260:Female; D006801:Humans; D007223:Infant; D019570:Inhalation Exposure; D008297:Male; D009010:Monte Carlo Method; D011634:Public Health; D011829:Radiation Dosage; D011835:Radiation Protection; D011883:Radium / Q000008:administration & dosage* / Q000493:pharmacokinetics; D013326:Strontium Radioisotopes / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D013326:Strontium Radioisotopes; D011883:Radium