Understanding the Basics About Radiation

• Radiation Basics
• Differences Between Radiation Contamination and Exposure
• Types of Radiation
• Atomic number and atomic mass
• Periodic tables: look up data
• What is radioactive decay?
• Understanding effects of relative doses of radiation
• Radioactive properties, internal distribution and risk coefficients
• Isotopes of interest: properties, treatment, and fact sheets
• Categorization of radioisotopes by regulating agencies
• Radiation units of measure
• Radiation units and conversions
• 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
• Biological effects
• Allowable limits of radiation for the general public and radiation workers
• Common radiation exposures vs. exposures in radiation events
• Online textbook about radiation biology and acute and late radiation effects
• Exposure of the US population to ionizing radiation
• See also:
  • Emergency Worker Exposure Guidelines in the Early Phase of a Radiation Incident

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

• Radiation (OSHA)
• Introduction to ionizing radiation (OSHA)
• Ionizing radiation (PDF - 2.34 MB) (Argonne National Laboratory)
• Radiation: Non-ionizing and Ionizing (EPA)

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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)

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• Periodic Table (Wikipedia)

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• Decay Rate/Half-life of Radioisotopes (Illustrations)
• Radioactive decay (EPA)

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• 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)

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• Radioactive Properties, Internal Distribution, and Risk Coefficients (PDF - 2.34 MB) (Argonne National Laboratory)

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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.

View/Print as PDF (PDF - 74 KB)

Isotope	Ionizing radiation decay mode	Radioactive half-life	Major exposure pathways	Focal accumulation	Treatment: References for use	Fact sheets (CDC, ATSDR, EPA, Argonne Natl. Lab, Wikipedia)
Americium (Am-241)	α	458 years	Inhalation Skin	Lungs Liver Bone Bone marrow	DTPA† *	CDC ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Californium (Cf-252)	α, γ	2.6 years	Inhalation Ingestion	Bone Liver	DTPA*	Argonne (PDF - 2.34 MB) Wikipedia
Cesium (Cs-137)	β, γ	30 years	Inhalation Ingestion	Follows potassium; renal excretion	Prussian blue, insoluble† *	CDC ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Cobalt (Co-60)	β, γ	5.26 years	Inhalation	Liver	Succimer (DMSA)§ (DailyMed) DTPA* EDTA§ N-Acetyl-L-cysteine§	CDC ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Curium (Cm-244)	α, γ, neutron	18 years	Inhalation Ingestion	Liver Bone	DTPA† *	Argonne (PDF - 2.34 MB) Wikipedia
Iodine (I-131)	β, γ	8.1 days	Inhalation Ingestion Skin	Thyroid	Potassium iodide† * Saturated solution of potassium iodide§ Propylthiouracil§ Methimazole§ Potassium iodate§	CDC ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Iridium (Ir-192)	β, γ	74 days	N/A	Spleen	Consider DTPA* Consider EDTA§	CDC Argonne (PDF - 2.34 MB) Wikipedia
Isotope	Ionizing radiation decay mode	Radioactive half-life	Major exposure pathways	Focal accumulation	Treatment: References for use	Fact sheets (CDC, ATSDR, EPA, Argonne Natl. Lab, Wikipedia)
Phosphorus (P-32)	β	14.3 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)	Wikipedia
Plutonium (Pu-239)	α	24,100 years	Inhalation (limited absorption)	Lung Bone Bone marrow Liver Gonads	DTPA§ DFOA§ EDTA§ DTPA + DFOA§	CDC ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia IEER
Polonium (Po-210)	α	138.4 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 - 2.34 MB) HPS (PDF - 492 KB) NRC Wikipedia More references
Radium (Ra-226)	α, β, γ	1,602 years	Ingestion	Bone	Aluminum hydroxide* Barium sulfate* Sodium alginate§ Calcium phosphate§	ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Strontium (Sr-90)	β	28 years	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 - 2.34 MB) Wikipedia
Isotope	Ionizing radiation decay mode	Radioactive half-life	Major exposure pathways	Focal accumulation	Treatment: References for use	Fact sheets (CDC, ATSDR, EPA, Argonne Natl. Lab, Wikipedia)
Thorium (Th-232)	α	1.41 x 1010 years	Inhalation Ingestion	Bone	Consider DTPA*	ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Tritium (H-3)	β	12.5 years	Inhalation Ingestion Skin	Whole body	Water diuresis*	EPA Public Health England (PHE), formerly Health Protection Agency (HPA), (UK) Wikipedia
Uranium (U-235)	α	7.1 x 108 years	Inhalation Ingestion	Kidneys Bone	Sodium bicarbonate* For high level intake consider off-label diuretics and/or dialysis§	CDC ATSDR EPA Argonne (PDF - 2.34 MB) Wikipedia
Yttrium (Y-90)¶	β	64 hours	Inhalation Ingestion	Bone	DTPA* EDTA§	Argonne ¶ (PDF - 2.34 MB) Wikipedia

• Summary of Radioactive Properties for Selected Radionuclides (PDF - 2.34 MB) (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)

• Understanding Radiation - Topics: Polonium 210 (Public Health England [PHE], formerly Health Protection Agency [HPA])
• Individual Monitoring Conducted by the Health Protection Agency in the London Polonium-210 Incident (Public Health England [PHE], formerly Health Protection Agency [HPA])
• 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 Apr 20;5(2):94-122. [PubMed Citation]

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Principles of Radiation Safety

• Types of Ionizing Radiation and Shielding Required (Illustration)
• Types of Ionizing Radiation and Shielding Required: Video (HHS/CDC) (YouTube - 1:44 min)
• Time, Distance, and Shielding: Video (DOE/TEPP/MERRTT) (YouTube - 2:15 min)
• Factors that Decrease Radiation from Exposure - Time, Distance, Shielding (Illustration)
• Protecting Yourself from Radiation (EPA)
• ALARA principle ("As Low As Reasonably Achievable"): making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical.
• Personal Protective Equipment
• 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

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Radiation Detection Devices

• Radiation Detection Devices

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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)

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• 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)

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Biological Effects

• Tapio S, Little MP, Kaiser JC, Impens N, Hamada N, Georgakilas AG, Simar D, Salomaa S. Ionizing radiation-induced circulatory and metabolic diseases. Environ Int. 2021 Jan;146:106235. [PubMed Citation]
• Kim JH, Jenrow KA, Brown SL. Mechanisms of radiation-induced normal tissue toxicity and implications for future clinical trials. Radiat Oncol J. 2014 Sep;32(3):103-15. [PubMed Citation]
• Videos
  • Biological Effects of Radiation (YouTube - 2:48 minutes) (DOE/TEPP/MERRTT)
  • Biological Effects of Radiation (YouTube - 2:26 minutes) (HHS/CDC)
• Radiation Epidemiology for Public Health Decision Making (course available until December 23, 2021, with continuing education credits)
  • Course's 8 Video Modules
• Linear No-threshold (LNT) Model for Radiation Effects
  • Implications of Recent Epidemiologic Studies for the Linear-Nonthreshold Model and Radiation Protection (NCRP Commentary No. 27), Bethesda, MD, 2018.
    • Smith G. Review of NCRP Commentary No. 27: Implications of recent epidemiologic studies for the linear-nonthreshold model and radiation protection. J Radiol Prot. 2019 Mar;39(1):314-320. [PubMed Citation]
  • Linear No-threshold Model of Carcinogenic Radiation Effects at Very Low Doses (PDF - 141 KB) (Brief overview by Dr. John Boice) (NCRP)
  • Brooks AL, Morgan WF, Feinendegen LE. 2015 Health Physics Society Symposium, 13-14 July 2015, Health Risks From Low Doses and Low Dose-Rates of Ionizing Radiation. Health Phys. 2016 Mar;110(3):241-8. [PubMed Citation]
    • This articles summarizes the various topics covered in the symposium May 5 2016
• Blue Book: EPA Radiogenic Cancer Risk Models and Projections for the U.S. Population (EPA)
• Radiation Health Effects (Chronic exposure, Acute effects, Exposure Pathways, Sensitive populations (EPA)
• Effects in Children
  • Scientific Finding on Effects of Radiation Exposure of Children, (PDF - 4.4 MB) (UNSCEAR 2013 Report, Volume II, Scientific Annex B. See Part VI: Health Effects)
  • Grant EJ, Furukawa K, Sakata R, Sugiyama H, Sadakane A, Takahashi I, Utada M, Shimizu Y, Ozasa K. Risk of death among children of atomic bomb survivors after 62 years of follow-up: a cohort study. Lancet Oncol. 2015 Oct;16(13):1316-23. [PubMed Citation]
  • Signorello LB, Mulvihill JJ, Green DM, Munro HM, Stovall M, Weathers RE, Mertens AC, Whitton JA, Robison LL, Boice JD Jr. Congenital anomalies in the children of cancer survivors: a report from the childhood cancer survivor study. J Clin Oncol. 2012 Jan 20;30(3):239-45. [PubMed Citation]
• See also: Estimates of Cancer Following Radiation Exposure

Low Dose Effects

• Health Physics Society. Position Statement of the Health Physics Society PS010-4: Radiation Risk in Perspective. Health Phys. 2020 Jan;118(1):79-80. [PubMed Citation]
• The Future of Low Dose Radiation Research in the United States: Proceedings of a Symposium (NASEM, 2019)
  • Summarizes a 2-day symposium on the need for a long-term strategy to guide a low dose radiation research program in the United States.
  • Conference definition: "Low dose radiation exposures, generally taken to mean a dose less than 100 millisieverts (mSv), arise from natural background and a number of man-made circumstances including routine operations of nuclear energy production, nuclear waste management, research activities, accidents, and medical diagnostic procedures."
• Mothersill C, Rusin A, Seymour C. Towards a New Concept of Low Dose. Health Phys. 2019 Sep;117(3):330-336. [PubMed Citation]
• Low-Dose Radiation: Interagency Collaboration on Planning Research Could Improve Information on Health Effects (US Government Accountability Office, November 2017)
• Health Effects of Low Doses of Radiation: Perspectives on Integrating Radiation Biology and Epidemiology. (NCRP Commentary No. 24), National Council on Radiation Protection and Measurements, Bethesda, MD, 2015. Purchase required.

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Whole body

100 mrem in a year⁴
2 mrem in an hour

N/A

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

• Standards for Protection Against Radiation (10 CFR Part 20. Nuclear Regulatory Commission)
  
• Occupational Safety and Health Standards for Ionizing Radiation (29 CFR 1910.1096.
  Department of Labor, Occupational Safety and Health Administration)
• PAG Manual: Protective Action Guides and Planning Guidance for Radiological Incidents, EPA-400/R-17/001 (PDF - 1.48 MB) (EPA, January 2017)