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Understanding Radiation



Types of Radiation


Resources:

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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
 

Prototype of chemical symbol illustrating atomic number and atomic mass

 

  • 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

 

Chemical symbol of 2 isotopes of the element carbon: carbon 12 and carbon 14
 

Adapted from Atomic Shorthand (EPA)

 

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Periodic Tables: Look up Data

 

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What Is the Decay Rate/Half-life of an Isotope?

 

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Understanding Effects of Relative Doses of Radiation

 

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Radioactive Properties, Internal Distribution, and Risk Coefficients

 

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Isotopes of Interest: Properties, Treatment, and Fact Sheets*

* Adapted from "Radiation Bioterrorism," Tochner ZA, Lehavi O, Glatstein E, Chapter 207 in Harrison's Principles of Internal Medicine. DL Kasper, E Braunwald, AS Fauci , SL Hauser, DL Longo, JL Jameson, eds. 16th Edition, pp 1294-1300, McGraw Hill, 2005

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)


Print as PDF View/Print as PDF (PDF - 74 KB)

Isotope Name & Symbol

Ionizing Radiation Type

Radiological Half-life

Biologic Half-life (days)

Exposure Type

Mode of Contamination

Focal Accumulation in Body

Treatment

Related Isotopes:
Fact Sheets
(CDC, ATSDR, EPA,
Argonne Natl. Lab)

Americium
(Am-241)

α

458 years

73,000

Internal

Inhalation,
skin wounds

Lungs, liver,
bones, bone marrow

Chelation with DTPA

CDC (PDF - 73 KB);
ATSDR (PDF - 24 KB);
EPA;
Argonne (PDF - 39 KB)

Californium
(Cf-252)

α, γ

2.6 years

N/A

Internal

Lungs,
GI tract

Bone, liver

Chelation with DTPA

Argonne (PDF - 39 KB)

Cesium
(Cs-137)

β, γ

30 years

70

External,
Internal

Lungs,
GI tract,
wounds, follows potassium

Renal excretion

Ion exchange with
Prussian blue

CDC;
ATSDR (PDF - 25 KB);
EPA;
Argonne (PDF - 39 KB)

Cobalt
(Co-60)

β, γ

5.26 years

9.5

External,
Internal

Lungs

Liver

Gastric lavage;
Limited animal data suggest that DTPA, EDTA, L-cysteine, NAC (N-Acetyl-Cysteine), and glutathione may be effective in increasing urinary excretion. §

CDC (PDF - 74 KB);
ATSDR (PDF - 25 KB);
EPA;
Argonne (PDF - 38 KB)

Curium
(Cm-244)

α, γ, neutron

18 years

7300 (liver)
18,250 (bones)

Internal

Inhalation,
GI tract

Liver, bones (soluble Cm compounds)

Chelation with DTPA

Argonne (PDF - 42 KB)

Iodine
(I-131)

β, γ

8.1 days

138

Internal

Inhalation,
GI tract,
wounds

Thyroid

Potassium iodide, propylthiouracil, methimazole, sodium iodide

CDC (PDF - 75 KB);
ATSDR (PDF - 702 KB);
EPA;
Argonne (PDF - 38 KB)

Iridium
(Ir-192)

β, γ

74 days

50

External,
Internal

Not available

Spleen

Not available

CDC;
Argonne (PDF - 95 KB)

Isotope Name & Symbol

Ionizing Radiation Type

Radiological Half-life

Biologic Half-life (days)

Exposure Type

Mode of Contamination

Focal Accumulation in Body

Treatment

Related Isotopes:
Fact Sheets
(CDC, ATSDR, EPA,
Argonne Natl. Lab)

Phosphorus
(P-32)

β

14.3 days

1155

Internal

Inhalation,
GI tract,
wounds

Bones, bone marrow, rapidly replicating cells

Lavage,
Aluminum hydroxide,
Dibasic phosphates

 

Plutonium
(Pu-239)

α

2.2 x 104 years

73,000

Internal

Limited lung absorption, high retention

Lung, bones,
bone marrow,
liver, gonads

Chelation with DTPA

CDC (PDF - 80 KB);
ATSDR (PDF - 109 KB);
EPA;
Argonne (PDF - 58 KB)

Polonium
(Po-210)

α

138.4 days

60

Internal

Inhalation,
GI tract,
wounds

Spleen, kidneys, lymph nodes, bone marrow, liver, mucus lining cells of the lung

Lavage,
Dimercaprol

CDC;
Review article 1;
Review article 2 (PDF - 174 KB);
Argonne (PDF - 41 KB);
HPS (PDF - 79 KB);
NRC;
HPA

Radium
(Ra-226)

α, β, γ

1602 years

16,400

External,
Internal

GI tract

Bones

MgSO4 lavage,
Ammonium chloride,
Calcium,
Alginates,
Calcium gluconate

ATSDR (PDF - 112 KB);
EPA;
Argonne (PDF - 52 KB)

Strontium
(Sr-90)

β

28 years

18,000

Internal

Moderate GI tract

Bones - similar to calcium

Stable strontium,
Calcium,
Ammonium chloride,
Calcium gluconate,
Sodium alginate,
Aluminum-containing antacids

CDC (PDF - 73 KB);
ATSDR (PDF - 25 KB);
EPA;
Argonne (PDF - 39 KB)

Isotope Name & Symbol

Ionizing Radiation Type

Radiological Half-life

Biologic Half-life (days)

Exposure Type

Mode of Contamination

Focal Accumulation in Body

Treatment

Related Isotopes:
Fact Sheets
(CDC, ATSDR, EPA,
Argonne Natl. Lab)

Thorium
(Th-232)

α

1.41 x 1010 years

8,030
(bones)
700
(liver, total body)

Internal

Inhalation,
GI tract

Bones

Chelation with DTPA

ATSDR;
EPA;
Argonne (PDF - 49 KB)

Tritium
(H-3)

β

12.5 years

12

Internal

Inhalation,
GI tract,
wounds

Total body

Dilution with controlled water intake,
Diuretics

EPA;
HPA

Uranium
(U-235)

α

7.1 x 108 years

15

Internal

GI tract

Kidneys, bones

Sodium bicarbonate

CDC (PDF - 69 KB);
ATSDR (PDF - 91 KB);
EPA;
Argonne (PDF - 46 KB)

Yttrium
(Y-90)

β

64 hours

N/A

Internal

Inhalation,
GI tract

Bones

Chelation with DTPA

Argonne (PDF - 39 KB)

† Not FDA approved for this indication / Off-label use
‡ FDA approved for this indication
§ References:
  1. Llobet JM, Domingo JL, Corbella J. Comparison of antidotal efficacy of chelating agents upon acute toxicity of Co(II) in mice. Res Commun Chem Pathol Pharmacol. 1985 Nov;50(2):305-8. [PubMed Citation]
  2. Llobet JM, Domingo JL, Corbella J. Comparison of the effectiveness of several chelators after single administration on the toxicity, excretion and distribution of cobalt. Arch Toxicol. 1986 Apr;58(4):278-81. [PubMed Citation]
  3. Generic procedures for medical response during a nuclear or radiological emergency (PDF - 2225 KB) (IAEA April 2005)
¶ For Yttrium-90 radioactive properties and health concerns information, see Strontium-90 Human Health Fact Sheet

* Adapted from "Radiation Bioterrorism", Tochner ZA, Lehavi O, Glatstein E, Chapter 207 in Harrison's Principles of Internal Medicine. Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, eds. 16th Edition, pp 1294-1300, McGraw-Hill, 2005


 

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Radiation Units of Measure

 
Radioactivity
Absorbed Dose
Dose Equivalent
Exposure
Common Units
curie
(Ci)
Standard International Units
becquerel (Bq)
gray
(Gy)
sievert
(Sv)
coulomb/kilogram (C/kg)

Animation: Becquerel (IAEA)
 

 

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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))

 

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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

 

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Principles of Radiation Safety

 

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Radiation Detection Devices

 

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How to do a Survey for Radiation Contamination

Print this section

 

How to survey - Front of person How to survey - Back of person

  • 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))


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Personal Protective Equipment

 

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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)

 

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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:  

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Radiation Response Worker Exposure Guidelines 1, 2, 3

Total Effective Dose Equivalent (TEDE)
Guideline

Activity

Condition

5 rem

All occupational exposures

  • Dose limit to emergency workers: 5 rem
  • Use all reasonable measures to minimize dose
  • For most Radiological Dispersal Devices, radiation control measures will maintain exposures below 5 rem
  • Some rescues may involve exposures > 5 rem
  • When 5 rem limit is exceeded, worker monitoring must be made available and volunteers for such activities should be made fully aware of the risks

10 rem

Protecting valuable property necessary for public welfare (e.g., a power plant)

  • Exposures to emergency workers protecting valuable property necessary for public welfare may exceed 5 rem
  • Use all reasonable measures to minimize dose
  • When 5 rem limit is exceeded, worker monitoring must be made available and volunteers for such activities should be made fully aware of the risks
  • For potential doses > 10 rem, special medical monitoring programs should be employed, and exposure should be tracked in terms of the unit of absorbed dose (rad) rather than TEDE (rem).

25 rem

Lifesaving or protection of large populations

  • During large incidents (e.g., Improvised Nuclear Devices) exposures to emergency workers may exceed 5 rem
  • Emergency response activities may include: lifesaving, protection of large populations, prevention of mass spread of destruction
  • Use all reasonable measures to minimize dose
  • When 5 rem limit is exceeded, worker monitoring must be made available and volunteers for such activities should be made fully aware of the risks
  • For potential doses > 10 rem, special medical monitoring programs should be employed, and exposure should be tracked in terms of the unit of absorbed dose (rad) rather than TEDE (rem).
1 Adapted from Protective Action Guides for Radiological Dispersal Device (RDD) and Improvised Nuclear Device (IND) Incidents (PDF - 481 KB) (DHS/FEMA draft document, published in Federal Register January 3, 2006, Z-RIN 1660-ZA02)

2 Emergency response decisions resulting in worker exposure doses greater than 5 rem

  • Made by on-scene Incident Commander during incident when exceeding 5 rem is unavoidable
  • Reflect actual incident circumstances/worker activity (e.g., need to save lives or critical infrastructure)
  • Require informed consent from responding worker

3 Decision points for restricting response workers' activities have been recommended by various other agencies.

Agency

Summary Information

Original Document

National Council on Radiation Protection and Measurement (NCRP)

NCRP Radiation Protection Guidelines: Control of Radiation Dose in the Control Zones

Key Elements of Preparing Emergency Responders for Nuclear and Radiological Terrorism (NCRP Commentary No. 19, December 2005, page 19, purchase required; see Free Overview (PDF - 219 KB))

International Atomic Energy Agency (IAEA)

IAEA Emergency Worker Turn-back Dose Guidance

Manual for First Responders to a Radiological Emergency (PDF - 2.2 MB) (CTIF, IAEA, PAHO, WHO, October 2006, page 41)

Conference of Radiation Control Program Directors, Inc. (CRCPD)

CRCPD Turn-back Exposure Rates and Dose Guidelines

Handbook for Responding to a Radiological Dispersal Device (Dirty Bomb): First Responder's Guide: The First 12 Hours (CRCPD Publication 06-6) (PDF - 4.26 MB), page 28. Conference of Radiation Control Program Directors, Inc. Frankfort, Kentucky, 2006.

International Commission on Radiological Protection (ICRP)

ICRP Guidance for Occupational Exposure

Protecting People Against Radiation Exposure in the Event of a Radiological Attack (International Commission on Radiological Protection, ICRP Publication 96, 2005, page 51)

See also: Personal Protective Equipment (PPE)

 

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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

 

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New Estimates of Annual U.S. per Capita Exposure to Ionizing Medical Radiation

 
  • Preliminary reports from the National Council on Radiation Protection and Measurement (NCRP Scientific Committes 6-2) suggest that the annual U.S. per capital exposure to ionizing medical radiation in the United States rose from 0.54 millisieverts (0.054 rem) in 1980 to 3.2 millisieverts (0.32 rem) in 2006.
Adapted from report by the American Institute of Physics

 

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Sources of Ionizing Radiation Exposure to the General Public

 
Pie chart showing the distribution of ionizing radiation sources to the general public: radon 55%, medical x-rays 11%, nuclear medicine 4%, consumer products 3%, cosmic radiation 8%, terrestrial radiation 8%, internal radiation 11%
Natural Radiation Sources: 82%
Manmade Radiation Sources: 18%
Other: < 1%
Radon Medical x-rays
Occupational - 0.3%
Internal Nuclear medicine Fallout - <0.3%
Terrestrial Consumer products Nuclear fuel cycle - 0.1%
Cosmic Others Miscellaneous - 0.1%

Adapted from: Ionizing Radiation Exposure of the Population of United States
(National Council on Radiation Protection and Measurements (NCRP), Report No. 93, 1987)

 

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