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Understanding Radiation


Differences Between Radiation Contamination and Exposure

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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 the Significance of a Range of Radiation Doses: Charts from DOE

 

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Radioactive Properties, Internal Distribution, and Risk Coefficients

 

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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.
  • 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.
Print as PDF 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

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
Health Protection Agency (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


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:
More Polonium-210 references ¶ For Yttrium-90 radioactive properties and health concerns, see Strontium-90 Human Health Fact Sheet
 

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Radiation Units of Measure

UnitAbbreviationDefinitionComment
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)

See also:

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Radiation Units and Conversions

Radiation Units and Conversions

  • Define units of measure
  • Interactive tools for unit conversions
  • Prefixes and superscripts

 

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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))

See also: Video: Screening People for External Contamination: How to Use Hand-held Radiation Survey Equipment (HHS/CDC) Watch video


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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)

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)

 

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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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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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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.
    • 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
  • Annual US effective dose was calculated for the year 20061-4
  • 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
References:
  1. 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.
  2. 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]
  3. Recommendations of the International Commission on Radiological Protection, ICRP Publication 60, Ann. ICRP 1991; 21(1-3)
  4. Recommendations of the International Commission on Radiological Protection, ICRP Publication 103, Ann. ICRP 2007; 37(2-4)

 

 

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