Carbon 14 (¹⁴C)


Chromium 51 (⁵¹C)


Iodine 125 (¹²⁵I)


Phosphorus 32 (³²P)


Phosphorus 33 (³³P)


Sulfur 35 (³⁵S)


Tritium (³H)

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Carbon 14 (¹⁴C)


• Symbol: ¹⁴C
• States/Forms: Soluble, except gaseous

Physical Characteristics

• Radioactive Half Life (T_½): 5730 years
• Decay Type: Beta- (ß-)
• Maximum Energy Emission: 0.156 MeV
• Maximum Range in Air: 21-25 cm
• Maximum Range in Water/Tissue: 0.028 cm
• Maximum Range in Plexiglas or Lucite: 0.025 cm

Hazard Category

• A Level (High Hazard): >1.0 Ci
• B Level (Moderate Hazard): >10 mCi to 1.0 Ci
• C Level (Low Hazard): 0.1 mCi to 10 mCi

Radiological Characteristics

• 17% of beta particle energy transmitted through dead layer of skin.
• Critical organ: Fat tissue.
• Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).
• Internal exposure and contamination: Primary radiological concerns with ¹⁴C.
• External exposure: External exposure from weak ¹⁴C beta particles is not a major radiological concern.

Dosimetry

Film badges and dosimeter rings are not appropriate for monitoring ¹⁴C exposure.

Bioassay Requirements

Urinalysis and breath measurements of CO₂ may be required after spills or incidents of contamination.

External Radiation Hazards and Shielding

There is minimal external hazard with ¹⁴C, i.e. the glass vial containing the ¹⁴C provides sufficient shielding from the beta particles. If the skin is uniformly contaminated with ¹⁴C, 1 microcurie/cm² (µCi/cm²) will deliver a dose of 1100 miilirems per hour (mrems/hr) to the basal skin cells.

Hazards if Internally Deposited

• ALI (Annual Limit of Intake)
• 2400 µCi - by ingestion
• 2000 µCi - by inhalation
• DAC (Derived Air Concentration)
• 1 x 10^-6 µCi/mL

Survey Instrumentation

• A Geiger-Muller pancake/frisker can be used to detect ¹⁴C, however the survey meter probe must be within a very close range (< 1 inch).
• Geiger-Muller detectors have a very low efficiency (~3%) for counting low energy ¹⁴C beta particles.
• Smear surveys, using liquid scintillation counters, are required to detect removable ¹⁴C contamination.

Problems and Precautions

• Lab coats and protective gloves should always be worn when working with ¹⁴C to keep skin free from contamination, and gloves should be changed often.
• All waste in a ¹⁴C work area is considered to be contaminated. Work areas should be kept free of unnecessary items.
• Wastes should be segregated to those with ³H and ¹⁴C only.
• It is assumed that ingested or inhaled ¹⁴C labeled compounds are instantaneously distributed uniformly throughout the organs and tissues of the body, where they are retained with a biological half-life of 40 days.

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Chromium 51 (⁵¹C)


• Symbol: ⁵¹Cr
• States/Forms: Soluble

Physical Characteristics

• Radioactive Half Life (T_½): 27.7 days
• Decay Type: Electron (e^-) capture, Gamma, X-ray
• Maximum Energy Emissions:
• 0.752 MeV (e^- capture)
• 0.320 MeV (Gamma)
• 0.005 MeV (X-ray)

Hazard Category

• A Level (High Hazard): >1.0 Ci
• B Level (Moderate Hazard): >200 mCi to 1.0 Ci
• C Level (Low Hazard): 0.1 mCi to 200 mCi

Radiological Characteristics

• Critical organs: Liver (25%), bone (5%), lower large intestine, and kidneys
• Routes of intake: Ingestion, inhalation, skin contamination (absorption).
• Internal exposure and contamination: Primary radiological concerns with ⁵¹Cr.
• External exposure: Primary radiological concern with ⁵¹Cr.

Dosimetry

Film badges and dosimeter rings are required if 10 millicuries (mCi) or more is to be handled at a given time, or if 5 mCi levels are handled frequently.

Bioassay Requirements

Whole body monitoring. Urinalysis may be done.

External Radiation Hazards and Shielding

The exposure rate at 1 cm from 1 mCi is 180 millirads per hour (mR/hr).  The exposure rate varies directly with activity and inversely with the square of the distance.  ¼ inch of lead shielding should be used when working with concentrations > 1 microcurie (μCi).  ½ inch of lead shielding should be used when working with concentrations > 10 μCi.   

Hazards if Internally Deposited

• ALI (Annual Limit of Intake):
• 4 x 10⁴μCi – by ingestion
• 5 x 10⁴μCi – by inhalation   
• DAC (Derived Air Concentration):
• 2 x 10^-5 µCi/mL

Survey Instrumentation

• Liquid scintillation counter (efficiency 37%)
• NaI scintillation counter (efficiency 1-2%)

Problems and Precautions

• Lead shielding should be used when working with or storing 10 mCi of ⁵¹Cr or greater.  Stock solution vials should be handled in shields or with tongs or forceps.
• Lab coats and protective gloves should always be worn when working with ⁵¹Cr to keep skin free from contamination, and gloves should be changed often.
• Survey frequently.
• Waste should be segregated to those with half-lives from 15 days to less than 60 days.

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Iodine 125 (¹²⁵I)


• Symbol: ¹²⁵I
• States/Forms: Inorganic, Free Iodine

Physical Characteristics           

• Radioactive Half Life (T_½): 60 days
• Decay Type: Electron (e^-) capture, Gamma
• Maximum Energy Emission: 0.035 MeV (Gamma)

Hazard Category

• A Level (High Hazard): >10 mCi
• B Level (Moderate Hazard): >200 μCi  to 10 mCi
• C Level (Low Hazard): 0.1 μCi to 200 μCi

Radiological Characteristics

• Critical organ: Thyroid
• Routes of intake: Ingestion, inhalation, skin contamination (absorption).
• Internal exposure and contamination: Primary radiological concerns with ¹²⁵I
• External exposure: Concern for ¹²⁵I.                                                        

Dosimetry

Film badges and dosimeter rings are required if 5 millicuries (mCi) or more is to be handled at a given time, or if mCi levels are handled frequently.

Bioassay Requirements

Thyroid scans.

External Radiation Hazards and Shielding

The exposure rate at 1 cm from 1 mCi is 1.5 rads per hour (R/hr).  The exposure rate varies directly with activity and inversely with the square of the distance.  1/32 of an inch of lead shielding should be used when working with concentrations > 1 microcurie (μCi).  ½ inch of lead shielding should be used when working with concentrations > 1 mCi.

Hazards if Internally Deposited

• ALI (Annual Limit of Intake):
• 400 μCi – by ingestion
• 600 μCi – by inhalation
• DAC (Derived Air Concentration):
• 3 x 10^-8 µCi/mL

Survey Instrumentation

• GM survey meters have a poor efficiency of detection for ¹²⁵I. 

• Survey by smear test or use NaI (TI) Scintillation probes.



Problems and Precautions

• Store NaI-125 solutions at room temperature because freezing results in subsequent volatilization of radioiodine. 

• Avoid acidic solutions to minimize volatilization. 

• Wear two pair of gloves when handling radioiodine compounds.

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Phosphorus 32 (³²P)


• Symbol: ³²P
• States/Forms: Soluble

Physical Characteristics

• Radioactive Half Life (T_½): 14.3 days
• Decay Type: Beta^- (ß^-)
• Maximum Energy Emission: 1.71 MeV
• Maximum Range in Air: 611 cm
• Maximum Range in Water/Tissue: 0.76 cm
• Maximum Range in Plexiglas or Lucite: 0.61 cm

Hazard Category

• A Level (High Hazard): >100 mCi
• B Level (Moderate Hazard): >2 mCi to 100 mCi
• C Level (Low Hazard): 0.01 mCi to 2 mCi

Radiological Characteristics

• 95% of beta particle energy transmitted through dead layer of skin.
• Critical organs: Body tissues – 70%; Bone – 30%
• Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).
• Internal exposure and contamination: Primary radiological concerns with ³²P
• External exposure: Primary radiological concern with ³²P. 

Dosimetry

Film badges and dosimeter rings are required if 1 millicurie (mCi) or more is to be handled at a given time, or if millicurie levels are handled frequently.

Bioassay Requirements

Urinalysis may be required after spills or incidents of contamination.

External Radiation Hazards and Shielding

Assuming there is no backscatter or self-absorption, the dose rate at 10 cm is 2.7 rads/hour from an unshielded 1 mCi dried sample of ³²P.  If the skin is contaminated with ³²P, 1 microcurie/cm² (μCi/cm²) will deliver a dose of 9200 miilirads per hour (mrad/hr) to the basal cells of the epidermis.  Lead foil or sheets, or other high density materials should NEVER be used to shield ³²P directly due to the production of penetrating Bremsstrahlung x-rays.  Lead materials can be used as shielding from Bremsstrahlung x-rays ONLY if behind low-density plexiglass, acrylic, lucite, or wood shielding.

Hazards if Internally Deposited

• ALI (Annual Limit of Intake):
• 600 μCi – by ingestion (all compounds)
• 900 μCi – by inhalation (except phosphates)
• 400 μCi – by inhalation (phosphates)
• DAC (Derived Air Concentration):
• 2 x 10^-5 μCi/mL

Survey Instrumentation

• A Geiger-Muller survey detector with a pancake/frisker probe can be used to detect ³²P.  The counting efficiency for ³²P is approximately 25%.
• A low-energy NaI probe can only be used to detect Bremsstrahlung x-rays.
• Liquid scintillation counters should be used to detect removable surface ³²P contamination using smears or swabs.

Problems and Precautions

• Phosphorus-32 is commonly the highest energy radionuclide encountered in a research setting, and thus requires special caution.  Exposure should be avoided and handling should be limited as much as possible.
• Always wear a lab coat, disposable gloves, and safety goggles when working with ³²P.
• Bremsstrahlung x-ray production must be avoided by working behind low Z shielding, preferably transparent materials.
• Surveys should be conducted frequently and gloves should be changed often.
• Waste should be segregated to those with half-lives of less than 19 days.

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Phosphorus 33 (³³P)


• Symbol: ³³P
• States/Forms: Soluble

Physical Characteristics

• Radioactive Half Life (T_½): 25 days
• Decay Type: Beta^- (ß^-)
• Maximum Energy Emission: 0.249 MeV
• Maximum Range in Air: 49 cm
• Maximum Range in Water/Tissue: 0.06 cm
• Maximum Range in Plexiglas or Lucite: 0.05 cm

Hazard Category

• A Level (High Hazard): >1 Ci
• B Level (Moderate Hazard): >20 mCi to 1 Ci
• C Level (Low Hazard): 0.1 mCi to 20 mCi

Radiological Characteristics

• 40% of beta particle energy transmitted through dead layer of skin.
• Critical organs: Bone marrow – 30%; Body tissues – 70%
• Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).
• Internal exposure and contamination: Primary radiological concerns with ³³P.
• External exposure: Minimal concern for ³³P.

Dosimetry

Film badges and dosimeter rings are not appropriate for monitoring ³³P exposure.

Bioassay Requirements

Urinalysis may be required after spills or incidents of contamination.

External Radiation Hazards and Shielding

There is minimal external hazard with ³³P, i.e. the glass vial containing the ³³P provides sufficient shielding from the beta particles, however lucite or plexiglas may be used as shielding.  If the skin is uniformly contaminated with ³³P, 1 microcurie/cm² (Ci/cm²) will deliver a dose of 3200 miilirems per hour (mrems/hr) to the basal skin cells.

Hazards if Internally Deposited

• ALI (Annual Limit of Intake):
• 4000 μCi – by ingestion
• 6000 μCi – by inhalation
• DAC (Derived Air Concentration):
• 3 x 10^-6 μCi/mL

Survey Instrumentation

• A Geiger-Muller survey detector with a pancake/frisker probe can be used to detect ³³P.  The counting efficiency for ³³P is approximately 6%.
• Liquid scintillation counters should be used to detect removable surface ³³P contamination using smears or swabs.

Problems and Precautions

• Lab coats and protective gloves should always be worn when working with ³³P to keep skin free from contamination, and gloves should be changed often.

• All waste in a ³³P work area is considered to be contaminated.  Work areas should be kept free of unnecessary items.

• Drying can form airborne ³³P contamination.

• Waste should be segregated to those with half-lives from 19 days to less than 65 days.

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Sulfur 35 (³⁵S)


• Symbol: ³⁵S
• States/Forms: Soluble, except gaseous

Physical Characteristics

• Radioactive Half Life (T_½): 87 days
• Decay Type: Beta^- (ß^-)
• Maximum Energy Emission: 0.167 MeV
• Maximum Range in Air: 26 cm
• Maximum Range in Water/Tissue: 0.04 cm
• Maximum Range in Plexiglas or Lucite: 0.025 cm

Hazard Category

• A Level (High Hazard): >1 Ci
• B Level (Moderate Hazard): >20 mCi to 1 Ci
• C Level (Low Hazard): 0.1 mCi to 20 mCi

Radiological Characteristics

• ~15% of beta particle energy transmitted through dead layer of skin.

• Critical organs: Testes

• Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).

• Internal exposure and contamination: Primary radiological concerns with ³⁵S.

• External exposure: Minimal concern for ³⁵S. 


Dosimetry

Film badges and dosimeter rings are not appropriate for monitoring ³⁵S exposure.

Bioassay Requirements

Urinalysis may be required after spills or incidents of contamination.

External Radiation Hazards and Shielding

There is minimal external hazard with ³⁵S, i.e. the glass vial containing the ³⁵S provides sufficient shielding from the beta particles, however lucite or plexiglas may be used as shielding.  If the skin is uniformly contaminated with ³⁵S, 1 microcurie/cm² (μCi/cm²) will deliver a dose of 1200 miilirads per hour (mrad/hr) to the basal skin cells.

Hazards if Internally Deposited

• ALI (Annual Limit of Intake):
• 1 x 10⁴μCi – by ingestion
• 6 x 10^-6μCi – by inhalation
• DAC (Derived Air Concentration):
• 2 x 10 ^-8 µCi/mL

Survey Instrumentation

• A thin window Geiger-Muller detector can be used to detect ³⁵S, however the survey meter probe must be within a very close range (< 1 inch).
• A Geiger-Muller survey detector with a pancake/frisker probe has a very low counting efficiency for ³⁵S (~4%).
• Liquid scintillation counters should be used to detect removable surface ³⁵S contamination using smears or swabs.

Problems and Precautions

• Lab coats and protective gloves should always be worn when working with ³⁵S to keep skin free from contamination, and gloves should be changed often.

• All waste in a ³⁵S work area is considered to be contaminated.  Work areas should be kept free of unnecessary items. 

• ³⁵S compounds are often volatile or produce volatile products.  ³⁵S should be opened and handled in a fume hood. 

• Activated charcoal should be used when incubating samples. 

• Waste should be segregated to those with half-lives from 65 days to less than 90 days.

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Tritium (³H)

• Symbol: ³H
• States/Forms: Soluble, except gaseous

Physical Characteristics

• Radioactive Half Life (T_½): 12.3 years
• Decay Type: Beta^-  (ß^-)
• Maximum Energy Emission: 0.0186 MeV
• Maximum Range in Air: 0.6 cm
• Maximum Range in Water/Tissue: 0.0006 cm

Hazard Category

• A Level (High Hazard): >10.0 Ci
• B Level (Moderate Hazard): >25 mCi per item to 10.0 Ci possession
• C Level (Low Hazard): 1-25 mCi per item to 100mCi possession

Radiological Characteristics

• 0% of beta particle energy transmitted through dead layer of skin.

• Critical organ: Body water or tissue.

• Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).

• Internal exposure and contamination: Primary radiological concerns with ³H.

• External exposure: External exposure from weak ³H beta particles is not a major radiological concern


Dosimetry

Film badges and dosimeter rings are not appropriate for monitoring ³H exposure.

Bioassay Requirements

Routine urinalysis is required after handling 100 microcuries (μCi) or greater of ³H.  Spot checks may be necessary following spills or incidents of contamination.

External Radiation Hazards and Shielding

There is minimal external hazard with ³H, i.e. the vial containing the ³H provides sufficient shielding from the beta particles.  If the skin is contaminated with ³H, the betas will not be able to penetrate through the dead layer of skin.  However, if ³H is absorbed into the body via ingestion or cuts in the skin, it will cause a radiation dose.

Hazards if Internally Deposited

• ALI (Annual Limit of Intake)
• 80 mCi – by ingestion or inhalation
• DAC (Derived Air Concentration)
• 2.0 x 10^-5 μCi/mL

Survey Instrumentation

• Tritium cannot be detected using a Geiger-Muller or NaI survey meter.

• Smear surveys, using liquid scintillation counters, are required to detect ³H contamination.



Problems and Precautions

• Lab coats and protective gloves should always be worn when working with ³H to keep skin free from contamination, and gloves should be changed often.

• All waste in a ³H work area is considered to be contaminated.  Work areas should be kept free of unnecessary items.

• Wastes should be segregated to those with ³H and ¹⁴C only.