Evaluating the Reliability of Biokinetic and Dosimetric Models and Parameters Used to Assess Individual Doses for Risk Assessment Purposes

Issued June 22, 1998. Includes Bibliographical References And Index. Preface......Page 3 Contents......Page 4 1. Introduction......Page 8 2.1 ICRP Publication 30 Gastrointestinal Tract Model......Page 10 2.3 Kinetics of Gastrointestinal Tract Motility: Stomach......Page 12 2.3.2 Review of Adult Gastric Kinetics......Page 13 2.4 Kinetics of Gastrointestinal Tract Motility: Small Intestine......Page 15 2.4.2 Review of Small Intestinal Tract Kinetics......Page 16 2.5 Kinetics of Gastrointestinal Tract Motility: Large Intestine......Page 19 2.5.2 Review of Large Intestinal Tract Kinetics......Page 20 2.6.2 Current Status of Gut Absorption Determination......Page 22 2.6.3 Remaining Areas of Concern......Page 25 2.7.3 Large Intestine......Page 26 2.7.4 Comparison of RIDIC Model and ICRP Publication 30 Model......Page 27 3.2 Respiratory Tract Models......Page 30 3.3 Characteristics of the Respiratory Tract Important for Purposes of Radiation Protection......Page 31 3.4 Uncertainties in Respiratory Tract Models......Page 32 3.5 Comparison of ICRP Respiratory Tract Models......Page 33 3.6.2 Particle Retention......Page 37 3.7 ICRP Publication 66 Respiratory Tract Model......Page 38 3.8 NCRP Respiratory Tract Model......Page 39 3.9 Alterations in the Structure of Lung Model......Page 40 3.10 Comparison of the New Respiratory Tract Models......Page 41 3.10.1 Deposition......Page 43 3.10.2 Retention......Page 45 3.10.4 Dosimetry of the Respiratory Tract......Page 46 3.11 Impact of the New Respiratory Tract Models......Page 48 4. Sources of Uncertainty in the Models Used in Radiation Protection to Describe Other Routes of Radionuclide Uptake (Wounds and Absorption Through Skin)......Page 49 5.2.1 Models Used in ICRP Publication 30......Page 50 5.2.2 Recent Trends in Model Formulation......Page 52 5.3 Types of Information Used to Construct Biokinetic Models for Radioelements......Page 53 5.4 Examples of the Use of “Direct Information” on Humans in the Construction of Biokinetic Models......Page 54 5.5 Biological Variability in Humans......Page 55 5.5.1 Example 1: Inter-individual Variation in the Biokinetics of Strontium......Page 56 5.5.2 Example 2: Inter-individual Variation in the Biokinetics of Barium......Page 58 5.5.3 Example 3: Inter-individual Variation in the Biokinetics of Uranium......Page 59 5.5.4 Example 4. Inter-individual Variation in Plasma Clearance of Drugs......Page 60 5.6 Use of Reference Distributions of Elements in the Development of Models......Page 62 5.7.1 Examples of Interspecies Extrapolation in ICRP Models......Page 65 5.7.2 The Basis for Interspecies Extrapolation of Biokinetic Data......Page 68 5.7.3 Attempts to Establish Universal Laws of Interspecies Scaling......Page 69 5.7.4 Counterexamples to the Assumption of a “General Biological Regularity”......Page 71 5.7.5 Selection of the Most Nearly Appropriate Animal Model(s) for Man......Page 72 5.8 Use of “Chemical Analogy” in Biokinetic Modeling: Some Examples and Counterexamples......Page 76 6.1 Dosimetric Concepts and Quantities......Page 80 6.2 Description of the Dosimetric Models and Identification of the Main Sources of Uncertainty......Page 83 6.2.1 Main Sources of Uncertainties in the Specific Effective Energies for Penetrating Radiations......Page 85 6.2.2 Main Sources of Uncertainty in the Specific Effective Energy Values for Nonpenetrating Radiations......Page 90 6.3 Summary of Dosimetric Uncertainties......Page 93 7. Sources of Uncertainty in the Models Used in Radiation Protection to Estimate Radiation Doses from External Irradiation Attributable to Radionuclides in the Environment......Page 95 7.1 Immersion Dose......Page 96 7.2 Ground Deposition Dose......Page 98 8.1 Model Validation......Page 100 8.2 Parameter Uncertainty Analysis......Page 102 8.3 Direct Assignment of Subjective Uncertainty to the Model Result......Page 103 8.3.1 Estimating the Reliability of a Model or Model Components, Based on the Quality of the Underlying Information......Page 104 8.3.2 Examples of Subjective Quantification of the Reliability of Selected Results of ICRP Publication 30 Biokinetic and Dosimetric Models......Page 107 9. Summary......Page 112 References......Page 115 The NCRP......Page 125 NCRP Commentaries......Page 126 Annotation A commentary prepared by Scientific Committee 57-16 on Uncertainty in the Application of Metabolic Models. Coverage includes: sources of uncertainty in the gastrointestinal tract models used in radiation protection; sources of uncertainty in the biokinetic models used in radiation protection; reliability of dose coefficients for estimation of risk to individuals; and sources of uncertainty in the respiratory tract models used in radiation protection. The intent of the work is to present the strengths and weaknesses of the currently-used biokinetic and dosimetric models and some examples of how estimates of uncertainties can be formulated. Annotation copyrighted by Book News, Inc., Portland, OR