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Understanding Radiation Types of Radiation Atomic number and atomic mass Periodic tables: look up data What is the decay rate/half-life of an isotope? Understanding effects of relative doses of radiation Radioactive properties, internal distribution and risk coefficients Isotopes of interest: properties, treatment, and fact sheets Radiation units of measure Radiation unit conversion factors Radiation unit prefixes Principles of radiation safety Radiation detection devices How to do a survey for radiation contamination Personal protective equipment Annual limits of intake (ALIs) for radioactive isotopes in the workplace Allowable limits of radiation for the general public and radiation workers Common radiation exposures vs. exposures in radiation events Exposure of the US population to ionizing radiation See also: Emergency Worker Exposure Guidelines in the Early Phase Multimedia Library: Animations, Illustrations, Photos Types of Radiation Electromagnetic radiation Examples: ultraviolet, visible light, x-rays, gamma rays No mass, no charge Particulate radiation Examples: alpha particles, beta particles, neutrons All have mass Some have charge (alpha, beta), some have no charge (neutron) Ionizing radiation (OSHA) Radiation with sufficient energy to eject electrons from atoms (ionization) Non-ionizing radiation (OSHA) Radiation without sufficient energy to produce ionizations Video: Radiation Principles (HHS/CDC) Video: Types of Ionizing Radiation and Shielding Required (HHS/CDC) Animations: Ionization (IAEA) Animation: Alpha Radiation (IAEA) Animation: Beta and Gamma Radiation (IAEA) Illustration: Neutron (OSHA) Resources: Radiation (OSHA) Introduction to ionizing radiation (OSHA) Ionizing radiation (PDF - 76 KB) (Argonne National Laboratory) Ionizing radiation fact book (PDF - 1.12 MB) (EPA) top of page Atomic Number and Atomic Mass The illustration below shows the chemical symbol for the hypothetical element "X" The number of protons in the nucleus is represented by "Z", the atomic number All the isotopes of an element have the same "Z" The atomic mass of the element (number of protons plus the number neutrons) is represented by "A" "A" is usually placed to the left above the element symbol The number of neutrons in the nucleus is equal to A minus Z     Two different forms, or isotopes, of carbon are shown below: Carbon-12: with 6 protons and 6 neutrons and an atomic mass of 12 Carbon-14: with 6 protons and 8 neutrons and an atomic mass of 14     Adapted from Atomic Shorthand (EPA)   top of page Periodic Tables: Look up Data Radionuclide/Isotopes Database (Lund/Lawrence Berkeley National Laboratory, Nuclear Science Division) Periodic Table (Lund/Lawrence Berkeley National Laboratory, Nuclear Science Division)   top of page What Is the Decay Rate/Half-life of an Isotope? Decay Rate/Half-life of Radioisotopes (Illustrations)   top of page Understanding the Significance of a Range of Radiation Doses: Charts from DOE Ionizing Radiation Dose Ranges (Rem) (PDF - 204 KB) (NF Metting, DOE, Office of Science, Office of Biological and Environmental Research, June 2010) Ionizing Radiation Dose Ranges (Sievert) (PDF - 207 KB) (NF Metting, DOE, Office of Science, Office of Biological and Environmental Research, June 2010) Low Dose Radiation Research Program: Image Gallery (Department of Energy)   top of page Radioactive Properties, Internal Distribution, and Risk Coefficients Radioactive Properties, Internal Distribution, and Risk Coefficients (PDF - 32 KB) (Argonne National Laboratory)   top of page Isotopes of Interest: Properties, Treatment, and Fact Sheets Information in this table adapted from: Management of Persons Contaminated with Radionuclides: Handbook (NCRP Report No. 161, Vol. I), National Council on Radiation Protection and Measurements, Bethesda, MD, 2008. Tochner ZA, Glatstein E, Internal Contaminant Radionuclides: Properties and Treatment (Table 216-1) in "Chapter 216: Radiation Bioterrorism," in Harrison's Principles of Internal Medicine, 17th Edition, Fauci AS, Longo DL, Kasper DL, Braunwald E, Jameson JL, Loscalzo J, Hauser SL, eds., pp. 1358-1364, McGraw Hill, 2008. View/Print as PDF (PDF - 74 KB) Isotope Ionizing radiation decay mode Radioactive half-life Biological half-life Major exposure pathways Focal accumulation Treatment: References for use Fact sheets (CDC, ATSDR, EPA, Argonne Natl. Lab) Americium (Am-241) α 458 years 73,000 days Inhalation Skin Lungs Liver Bone Bone marrow DTPA† * CDC ATSDR EPA Argonne (PDF - 39 KB) Californium (Cf-252) α, γ 2.6 years N/A Inhalation Ingestion Bone Liver DTPA* Argonne (PDF - 39 KB) Cesium (Cs-137) β, γ 30 years 70 days Inhalation Ingestion Follows potassium; renal excretion Prussian blue, insoluble† * CDC ATSDR EPA Argonne (PDF - 39 KB) Cobalt (Co-60) β, γ 5.26 years 9.5 days Inhalation Liver Succimer (DMSA)§ (DailyMed) DTPA* EDTA§ N-Acetyl-L-cysteine§ CDC ATSDR EPA Argonne (PDF - 38 KB) Curium (Cm-244) α, γ, neutron 18 years Liver: 7,300 days Bone: 18,250 days Inhalation Ingestion Liver Bone DTPA† * Argonne (PDF - 42 KB) Iodine (I-131) β, γ 8.1 days 138 days Inhalation Ingestion Skin Thyroid Potassium iodide† * Saturated solution of potassium iodide§ Propylthiouracil§ Methimazole§ Potassium iodate§ CDC ATSDR EPA Argonne (PDF - 38 KB) Iridium (Ir-192) β, γ 74 days 50 days N/A Spleen Consider DTPA* Consider EDTA§ CDC Argonne (PDF - 95 KB) Isotope Ionizing radiation decay mode Radioactive half-life Biological half-life Major exposure pathways Focal accumulation Treatment: References for use Fact sheets (CDC, ATSDR, EPA, Argonne Natl. Lab) Phosphorus (P-32) β 14.3 days 1,155 days Inhalation Ingestion Skin Bone Bone marrow Rapidly replicating cells Hydration + Phosphate drugs Sodium glycerophosphate§ Sodium phosphate§ Potassium phosphate§ Calcium carbonate§ Aluminum hydroxide§ Aluminum carbonate§ Sevelamer§ (DailyMed)   Plutonium (Pu-239) α 2.2 x 104 years 73,000 days Inhalation (limited absorption) Lung Bone Bone marrow Liver Gonads DTPA§ DFOA§ EDTA§ DTPA + DFOA§ CDC ATSDR EPA Argonne (PDF - 58 KB) Polonium (Po-210) α 138.4 days 60 days Inhalation Ingestion Skin Spleen Kidneys Lymph nodes Bone marrow Liver Lung mucosa Gastric Lavage Dimercaprol (BAL)* Succimer (DMSA)§ (DailyMed) D-Penicillamine§ (DailyMed) CDC Argonne (PDF - 41 KB) HPS (PDF - 492 KB) NRC More references Radium (Ra-226) α, β, γ 1,602 years 16,400 days Ingestion Bone Aluminum hydroxide* Barium sulfate* Sodium alginate§ Calcium phosphate§ ATSDR EPA Argonne (PDF - 52 KB) Strontium (Sr-90) β 28 years 18,000 days Inhalation Ingestion Bone Inhalation: Calcium gluconate§ Barium sulfate§ Ingestion: Rx is the same as for radium (see above). Additional Rx may include stable strontium compounds: Strontium lactate§ Strontium gluconate§ CDC ATSDR EPA Argonne (PDF - 39 KB) Isotope Ionizing radiation decay mode Radioactive half-life Biological half-life Major exposure pathways Focal accumulation Treatment: References for use Fact sheets (CDC, ATSDR, EPA, Argonne Natl. Lab) Thorium (Th-232) α 1.41 x 1010 years Bone: 8,030 days Liver/total body: 700 days Inhalation Ingestion Bone Consider DTPA* ATSDR EPA Argonne (PDF - 49 KB) Tritium (H-3) β 12.5 years 12 days Inhalation Ingestion Skin Whole body Water diuresis* EPA Health Protection Agency (UK) Uranium (U-235) α 7.1 x 108 years 15 days Ingestion Kidneys Bone Sodium bicarbonate* For high level intake consider off-label diuretics and/or dialysis§ CDC ATSDR EPA Argonne (PDF - 46 KB) Yttrium (Y-90)¶ β 64 hours N/A Inhalation Ingestion Bone DTPA* EDTA§ Argonne ¶ (PDF - 39 KB) References for use † FDA approved: Countermeasures so marked have been approved as treatment for internal contamination with the listed radioisotope by the US Food and Drug Administration (FDA). * NCRP preferred: Countermeasures so marked have been listed as preferred treatments for internal contamination with the listed radioisotope by the National Council on Radiation Protection and Measurements [Management of Persons Contaminated with Radionuclides: Handbook (NCRP Report No. 161, Vol. I)]. Except where noted, use of these countermeasures has not been approved by the US Food and Drug Administration (FDA). § NCRP suggested: Countermeasures so marked have been listed as suggested treatments for internal contamination with the listed radioisotope by the National Council on Radiation Protection and Measurements [Management of Persons Contaminated with Radionuclides: Handbook (NCRP Report No. 161, Vol. I)]. Use of these countermeasures has not been approved by the US Food and Drug Administration (FDA). See also: Summary of Radioactive Properties for Selected Radionuclides (PDF - 145 KB) (Human Health Fact Sheet, Argonne National Laboratories, 2005) Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas (PDF - 2.34 MB) (Argonne National Laboratories, 2007) More Polonium-210 references Understanding Radiation - Topics: Polonium 210 (Health Protection Agency) Individual Monitoring Conducted by the Health Protection Agency in the London Polonium-210 Incident (Health Protection Agency) Jefferson RD, Goans RE, Blain PG, Thomas SH. Diagnosis and treatment of polonium poisoning. Clin Toxicol (Phila.) 2009 May; 47(5):379-92. [PubMed Citation] Harrison J, Leggett R, Lloyd D, Phipps A, Scott B. Polonium-210 as a Poison. J Radiol Prot. 2007 Mar;27(1):17-40. [PubMed Citation] Scott BR. Health risk evaluations for ingestion exposure of humans to polonium-210. Dose Response. 2007;5:94-122. (PDF - 175 KB) ¶ For Yttrium-90 radioactive properties and health concerns, see Strontium-90 Human Health Fact Sheet   top of page Radiation Units of Measure Unit Abbreviation Definition Comment Roentgen R The amount of energy absorbed in air For x-rays and gamma rays only Radiation absorbed dose rad The energy absorbed per gram of material 1 rad = 100 ergs/gram Important because it represents the amount of energy that is absorbed by the material of interest-e.g., person, organ, tissue, cells Roentgen equivalent man Rem The product of the amount of energy absorbed (rad) times the efficiency of radiation in producing damage rem = rad x (Wr) Accounts for the different degrees of damage produced by equal doses of different radiations, for example: Radiation Radiation Weighting Factor (Wr) x rays gamma rays beta particles 1 neutrons range 2-20 alpha particle 20 Gray* Gy 1 Gy = 100 rad 1 Gy = 1 joule/kilogram Sievert* Sv 1 Sv = 1 Gy x Wr 1 Sv = 100 rem Curie Ci The number of radioactive decays (disintegrations)/ unit of time 1 Ci = 2.2 x 1012 disintegrations/minute 1 Ci = 3.7 x 1010 disintegrations/second Becquerel* Bq The number of radioactive decays (disintegrations)/ unit of time 1 Bq = 60 disintegrations/minute 1 Bq = 1 disintegration/second * International units (SI) of Bequerel, Gray and Sievert are the currently favored expressions. Adapted from: Program on Technology Innovation: Evaluation of Updated Research on the Health Effects and Risks Associated with Low Dose Radiation (PDF - 903 KB) (Electric Power Research Institute [EPRI] document 1019227, Table 2-1, page 42, November 2009) top of page Radiation Unit Conversion Factors Unit of measure Conversion equivalent 1 curie = 3.7 x 1010 disintegrations/second 1 becquerel = 1 disintegration/second 1 millicurie (mCi) = 37 megabecquerels (MBq) 1 rad = 0.01 gray (Gy) 1 rem = 0.01 sievert (Sv) 1 roentgen (R) = 0.000258 coulomb/kilogram (C/kg) 1 megabecquerel (MBq) = 0.027 millicuries (mCi) 1 gray (Gy) = 100 rad 1 sievert (Sv) = 100 rem 1 coulomb/kilogram (C/kg) = 3880 roentgens Adapted from Measurement - Activity: How Much Is Present? (Radiation Emergency Assistance Center/Training Site (REAC/TS))   top of page Radiation Unit Prefixes Multiple Prefix Symbol 1012 tera T 109 giga G 106 mega M 103 kilo k 102 centi c 10-3 milli m 10-6 micro μ 10-9 nano n   top of page Principles of Radiation Safety Types of Ionizing Radiation and Shielding Required (Illustration) Video: Types of Ionizing Radiation and Shielding Required (HHS/CDC) Factors that Decrease Radiation from Exposure - Time, Distance, Shielding (Illustration) ALARA principle: making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical. Assessment of Occupational Exposure Due to Intakes of Radionuclides Safety Guide (PDF - 316 KB) (IAEA Safety Standards Series No. RS-G-1.2, 1999) Assessment of Occupational Exposure Due to External Sources of Radiation Safety Guide (PDF - 307 KB) (IAEA Safety Standards Series No. RS-G-1.3, 1999) Examples of Radiation Signs and Symbols for Work Areas, Buildings, Transportation of Cargo   top of page Radiation Detection Devices Radiation Detection Devices   top of page How to do a Survey for Radiation Contamination   Survey with Geiger-Mueller Detector Probe held about 1/2 inch from surface Move at a rate of 1 to 2 inches per second Follow a systematic pattern (see below) Document readings in counts per minute (CPM) on a body chart (PDF - 49 KB) Compare radiation survey results before and after decontamination procedure Use nuclear medicine and radiation therapy technologists or others familiar with the use of radiation detection instruments Goal is < 2 times background radiation reading In general, areas that register more than twice the previously determined background radiation level are considered contaminated. For accidents involving alpha particle emitters, if the reading is less than twice the background radiation level, the person is not contaminated to a medically significant degree. If the accident circumstances indicate that an alpha particle emitter (such as plutonium) or low-energy beta emitter could be a contaminant, a health physicist should always be consulted. Specifics of the survey Have the person stand on a clean pad. Instruct the person to stand straight, feet spread slightly, arms extended with palms up and fingers straight out. Monitor both hands and arms; then repeat with hands and arms turned over. Starting at the top of the head, cover the entire body, monitoring carefully the forehead, nose, mouth, neckline, torso, knees, and ankles. Have the person turn around; repeat the survey on the back of the body. Monitor the soles of the feet. Adapted from How to Detect Radiation (Radiation Emergency Assistance Center/Training Site (REAC/TS)) See also: Video: Screening People for External Contamination: How to Use Hand-held Radiation Survey Equipment (HHS/CDC) top of page Personal Protective Equipment Personal Protective Equipment OSHA Best Practices for Hospital-Based First Receivers of Victims (OSHA, Section B, January 2005, 1.93 MB) Practical Radiation Technical Manual: Personal Protective Equipment (PDF - 439 KB) (IAEA, 2004) Development of Models for Emergency Preparedness: Personal Protective Equipment, Decontamination, Isolation/Quarantine, and Laboratory Capacity (PDF - 4715 KB) (AHRQ, 2005)   top of page Annual Limits of Intake (ALIs) for Radioactive Isotopes in the Workplace1 Radioisotope Chemical Form Retention Time Ingestion ALI (μCi) Inhalation ALI (μCi)1 Americium-241 All compounds Weeks 8 x 10-1 6 x 10-3 Cesium-137 All compounds Days 1 x 102 2 x 102 Cobalt-60 All compounds, except Weeks 5 x 102 2 x 102   oxides,   hydroxides,   halides,   nitrates Years 2 x 102 3 x 101 Iodine-125 All compounds Days 4 x 101 6 x 101 Iodine-131 All compounds Days 3 x 101 5 x 101 Iridium-192 All compounds, except Days 9 x 102 3 x 102   halides,   nitrates,   metallic iridium Weeks ... 4 x 102   oxides,   hydroxides Years ... 2 x 102 Palladium-103 All compounds, except Days 6 x 103 6 x 103   nitrates Weeks ... 4 x 103   oxides,   hydroxides Years ... 4 x 103 Phosphorus-32 All compounds, except Days 6 x 102 9 x 102   phosphates of Zn2+,   S3+,   Mg2+,   Fe3+,   Bi3+;   lanthanides Weeks ... 4 x 102 Plutonium-239 All compounds, except Weeks 8 x 10-1 6 x 10-3   PuO2 Years ... 2 x 10-2 Radium-226 All compounds Weeks 2 x 100 6 x 10-1 Strontium-90 All soluble compounds except  SrTiO3 Days 3 x 101 2 x 101 All insoluble compounds and SrTiO3 Years ... 4 x 100 Tritium (Hydrogen-3) Water 8 x 104 8 x 104 Uranium-233 UF6, UO2F2, UO2(NO3)2 Days 1 x 101 1 x 100 UO3, UF4, UCI4 Weeks ... 7 x 10-1 UO2, U3O8 Years ... 4 x 10-2 Uranium-2342 UF6, UO2F2, UO2(NO3)2 Days 1 x 101 1 x 100 UO3, UF4, UCI4 Weeks ... 7 x 10-1 UO2, U3O8 Years ... 4 x 10-2 Uranium-2352 UF6, UO2F2, UO2(NO3)2 Days 1 x 101 1 x 100 UO3, UF4, UCI4 Weeks ... 8 x 10-1 UO2, U3O8 Years ... 4 x 10-2 Yttrium-90 All compounds, except Weeks 4 x 102 7 x 102   oxides,   hydroxides Years ... 6 x 102 1 Adapted from Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for Occupational Exposure (Appendix B to 10 CFR Part 20, Nuclear Regulatory Commission) According to the introduction to Appendix B of the reference above, "The ALIs and DACs for inhalation are given for an aerosol with an activity median aerodynamic diameter (AMAD) of 1 μm and for three classes (D,W,Y) of radioactive material, which refer to their retention (approximately days, weeks or years) in the pulmonary region of the lung." 2 For soluble mixtures of U-234, U-235 (and U-238) in air, chemical toxicity may be the limiting factor. 3 NRC Listing of ALIs by Isotope (NRC) 4 NCRP has published new, detailed guidance on Management of Persons Contaminated With Radionuclides: Handbook3 (NCRP Report No. 161, Volume I, Bethesda, MD, 2008). It recommends a new operational quantity, "Clinical Decision Guide" (CDG), as a replacement for ALI. CDG is designed "to provide a measure that physicians can use when considering the need for medical treatment for internally-deposited radionuclides or as a screening tool...". The new guidance updates NCRP Report No. 65: Management of Persons Accidentally Contaminated with Radionuclides (National Council on Radiation Protection and Measurements, Bethesda, MD, 1980)   top of page Allowable Limits of Radiation for the General Public and Radiation Workers1   Exposure Limits Intended to Protect Nuclear Regulatory Commission (NRC)2 Occupational Safety and Health Administration (OSHA)3 Non-occupational Exposure Limits (General Public) Whole body 100 mrem in a year4 2 mrem in an hour N/A    Occupational   Exposure Limits5 Whole body 5 rem/year 1.25 rem/quarter Lens of eye 15 rem/year 1.25 rem/quarter Skin 50 rem/year 7.5 rem/quarter Extremities 50 rem/year  18.75 rem/quarter Embryo/fetus     500 mrem/gestation N/A    Minors (< 18 years) 10% of adult annual dose 10% of adult quarterly dose 1 Exposure limit values in this table exclude exposures to natural sources of ionizing radiation (e.g., radon, cosmic radiation) and therapeutic or diagnostic medical sources of ionizing radiation (e.g., radiation therapy, nuclear medicine scans, arteriograms, x-rays, CT scans, etc.). 2 NRC provides guidance concerning allowable limits of exposure to personnel/employees at facilities using licensed sources (i.e., radiation workers) at workplaces like nuclear power plants, industrial food irradiation facilities, and nuclear medicine and radiation oncology departments. NRC also provides guidance on allowable limits of exposure to the general public concerning any exposure to manmade sources of radiation. 3 OSHA regulations only concern workplace or occupational exposures to ionizing radiation. 4 These limits apply to exposures to the general public from manmade sources of ionizing radiation (e.g., to people living in the vicinity of a nuclear power facility). 5 A maximum lifetime occupational dose (for adults) is defined as ≤ 5 x (N - 18) rem, where N = age in years at last birthday. References: Standards for Protection Against Radiation (10 CFR Part 20. Nuclear Regulatory Commission) Occupational Safety and Health Standards for Ionizng Radiation (29 CFR 1910.1096. Department of Labor, Occupational Safety and Health Administration)   top of page Common Radiation Exposures vs. Exposures in Radiation Events Common medical and natural background sources of radiation Approximate dose in rem Chest x-ray up to 0.03 Average annual dose from cosmic radiation to people living in Rocky Mountain States 0.06 - 0.08 Average annual dose from cosmic radiation to flight crew members 0.16 Average annual dose from exposure to natural sources of ionizing radiation to the US population (e.g., radon, cosmic rays) 0.2 - 0.3 CAT scan (whole body) 1 Recommended annual occupational exposure limit, excluding personal medical exposures and exposures from natural sources up to 5 rem per year Adverse health effects from higher dose exposures, including those possibly found after radiation events Approximate dose in rem No symptoms 15 No symptoms of illness; minor and temporary drop in counts of white blood cells and platelets 50 Possible Acute Radiation Syndrome; 10% of exposed individuals may have nausea/vomiting within 48 hours and a mild drop in blood counts 100 50% of exposed individuals will die within 30 days in the absence of appropriate medical care (LD 50/30) 300 - 400 Adapted from: Hall EJ. Radiobiology for the Radiologist. Lippincott Williams & Wilkins, 2000   top of page Exposure of the US Population to Ionizing Radiation The US population is exposed to various sources of ionizing radiation1-4, both naturally occurring and man-made. Ubiquitous, naturally occurring radiation: e.g., radon in homes, radiation from space, radionuclides in the body, naturally occurring terrestrial (ground) radiation, other. See Illustration of Background Radiation Medical tests and procedures: e.g., patients exposed to radiation during diagnostic tests and treatments Consumer products and activities involving radiation: e.g., building materials, commercial air travel by passengers, cigarette smoking, other Occupational exposure to workers: e.g., medical, aviation, commercial nuclear power, industry, commerce, other Miscellaneous sources: e.g., nuclear power generation, Department of Energy installations, decommissioning and radioactive waste, other Experts have devised a formula to calculate the annual dose of ionizing radiation from all these sources for the average individual in the US and for the US population as a whole1-4 This formula calculates a value called effective dose. What is effective dose? Annual US effective dose was calculated for the year 20061-4 Effective dose per individual: 6.2 mSv Ubiquitous background: 3.11 mSv Medical tests and procedures: 3.00 Sv Consumer products and activities: 0.13 mSv Occupational exposure: 0.005 mSv Miscellaneous sources: 0.003 mSv Collective effective dose for the entire US population (300 million people): 1,870,000 person-Sv See NCRP Report No. 160: Ionizing Radiation Exposure of the Population of the United States, Chapter 1 REMM discusses effective dose to provide some context for interpretation of possible risks from radiation in a radiation mass casualty emergency. Key EPA information about radiation doses in the US EPA: "Radiation Doses in Perspective": from naturally occurring and man-made sources EPA's RadNet data: national network of monitoring stations that regularly collect air, precipitation, drinking water, and milk samples for analysis of radioactivity More details Interactive tool: updated radiation data for your area Interactive tool: Calculate your own radiation dose/year References: Ionizing Radiation Exposure of the Population of the United States (NCRP Report 160), National Council on Radiation Protection and Measurements, Bethesda, MD, March 2009, Chapter 1. Mettler FA, Bhargavan M, Faulkner K et al. Radiologic and nuclear medicine studies in the United States and worldwide: frequency, radiation dose, and comparison with other radiation sources--1950-2007. Radiology. 2009 Nov; 253(2):520-31. Epub 2009 Sep 29. [PubMed Citation] Recommendations of the International Commission on Radiological Protection, ICRP Publication 60, Ann. ICRP 1991; 21(1-3) Recommendations of the International Commission on Radiological Protection, ICRP Publication 103, Ann. ICRP 2007; 37(2-4)     top of page

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