Environmental Health & Safety

Working with Specific Radioisotopes

 Common Radioisotopes and Safety Precautions (Select the radioisotope you are using in the lab)

H-3      C-14     P-32     S-35     I-125     Cr-51      

H-3

 
Tritium Hazard: The beta radiation from mCi quantities is not an external radiation hazard. However, ingestion, inhalation or absorption through the skin may result in an external exposure. Tritiated water may enter the body through either of these paths.
Physical Properties:

Half Life 12.28 yrs.

Radiation Beta

Max. Energy: 0.019 Mev (100%)

Range in Air 4.7mm

Limits

10 half lives: N/A

Sink disposal:

  • 360 uCi/month
  • 12 uCi/day*

* Average amount

Safety Precautions:

Follow General Precautions for working with radioactive material.
Most research involving tritium may be performed on a laboratory bench.
Shielding is not required.
Use liquid scintillation detector to monitor for contamination.
Urinalysis is required within 24 hours after working with 100 mCi or greater of tritiated water or tritium compounds.
Dispose of radioactive waste in accordance with requirements in the Radiation Safety Manual

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C-14

 
Carbon-14 Hazard The beta radiation from mCi quantities is not an external radiation hazard. However, ingestion and inhalation may result in an internal exposure.
Physical Properties:

Half Life 5730 yrs.

Radiation Beta

Max. Energy: 0.156 Mev (100%)


Range in Air 22 cm
 

Limits

10 half lives: N/A

Sink disposal:

  • 900 uCi/month
  • 30 uCi/day*

* Average amount

Safety Precautions

Follow General Precautions for working with radioactive material.
Most research involving C-14 may be performed on a laboratory bench.
Shielding is not required for C-14.
Use GM detector with pancake probe or liquid scintillation detector to monitor for contamination.
Urinalysis is required within 24 hours after working with 100 mCi or greater of C-14.
Dispose of radioactive waste in accordance with requirements in the Radiation Safety Manual.

 

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P-32

 
Phosphorus-32 Hazard The beta radiation from mCi quantities represents an external radiation hazard. Large quantities of material (100 mCi) can produce significant amounts of secondary radiation, Bremstrallung Radiation. Ingestion and inhalation are possible routes for an internal exposure.
Physical Properties:

 

Half Life 14.29 days

Radiation Beta

Max. Energy: 1.71 Mev
(100%)


Range in Air 6 meters

Range in Water: 8 mm

Limits

Ring dosimeter required for work with >500 uCi

10 half lives: 6 months

Sink disposal:

  • 360 uCi/month
  • 12 uCi/day*

* Average amount

Safety Precautions

Follow General Precautions for working with radioactive material.
Wear whole body (See limits for ring dosimeter)
Use 1 cm thick lucite shielding when handling mCi quantities of material.
For larger quantities of material add 3 to 6 mm of lead to the outside surface of the lucite shield.
Do not look into or work over an open container of P-32 without shielding.
Conduct dry-run experiments to ensure dexterity and speed of handling P-32.
Use remote handling tools to minimize skin exposure.
Routinely monitor gloves for contamination and replace if highly contaminated.
Routinely monitor work area for contamination during the experiment.
Urinalysis is required within 24 hours after working with 100 mCi or greater of P-32.
Conduct a thorough survey of work area with GM detector after experiment.
Isolate waste in a labeled, shielded container.
Dispose of radioactive waste in accordance with requirements in the Radiation Safety Manual.
 

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Equipment Suppliers   Dose Information for P-32

Dose rate for 1 mCi of P-32 over 1 cm-sq of skin

  • At 10 cm: 22 rads/hr
  • At 1 cm: 200 rads/hr
  • At surface of skin: 2,000 rads/hr

For 1 mCi P-32 in 1 ml of water

  • At surface: 780 rads/hr
     
 
 

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S-35

 
Sulfur-35 Hazard The beta radiation from mCi quantities is not an external radiation hazard. However, ingestion and inhalation may result in an internal exposure.
Physical Properties:

Half Life 87.4 days

Radiation beta

Max. Energy: .167 Mev (100%)


Range in Air 24 cm

Limits

10 half lives: 3 years

Sink disposal:

  • 300 uCi/month
  • 10 uCi/day*

* Average amount

Safety Precautions

Follow General Precautions for working with radioactive material.
Most research involving S-35 may be performed on a laboratory bench.
Shielding is not required.
Use GM detector with pancake probe or liquid scintillation detector to monitor for contamination.
Urinalysis is required within 24 hours after working with 100 mCi or greater of S-35.
Dispose of radioactive waste in accordance with requirements in Radiation
Safety Manual.
 

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I-125

 
Iodine-125 Hazard The hazard from I-125 is due to uptake to the thyroid. It is of particular concern when in the form of volatile sodium iodine.
Physical Properties:

 

Half Life 60.14 days

Radiation EC, Gamma

Energy:
Gamma: 0.035 Mev (6.5%)
Ka X-rays: 0.027 Mev (112.5%)
KB X-rays: 0.031 Mev (25.4%)


Half-value layer = 0.02 mm of lead

Limits

 

Ring dosimeter required for work with >1 mCi

10 half lives: 2 years

Sink disposal:

  • 360 uCi/month
  • 12 uCi/day*

* Average amount

Safety Precautions

Follow General Precautions for working with radioactive material.
Use lead foil (~3 mm thick) to shield mCi quantities of I-125.
Handle multi-mCi quantities with remote handling tools.
Use double gloves when working with volatile NaI.
Handle volatile NaI in fume hood.
A radioiodine fume hood is available through the Radiation Safety Office.
Film badges are required for work with I-125.
Use GM detector or liquid scintillation counter to monitor for I-125.
Keep containers of NaI closed when not in use to minimize release of volatile material.
A thyroid scan is required within 24 hours, if possible, but not later than 72 hours after working with volatile I-125.
Seal all waste containers with NaI to prevent release of volatile material.
Dispose of radioactive waste in accordance with requirements in the Radiation
Safety Manual.
Go to "Performing Iodinations" for additional information.
 

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Equipment Suppliers   Dose Information for I-125

Dose Rate for a 1 millicurie point source is:

  • At 1 meter is < 1 mrem/hour
  • At 100 cm is 15.2 mrem/hour
  • At 10 cm is 1520 mrem/hour or 1.5 Rem/hour
 
 

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Cr-51

 
Chromium-51 Hazard The hazard from Cr-51 is from both external and internal exposure. External exposure from a 1 mCi point source of Cr-51 at 1 meter is 180 mR/hr. Internally insoluble compounds can deposit in the lung, the critical organ. The lower large intestine is the critical organ for an intake of soluble compounds.
Physical Properties

Half Life 27.7 days

Radiation EC, Gamma

Energy:
Gamma: 0.32 Mev (9.8%)
X-rays: 0.005 Mev (22.3%)
Auger Electron: 0.004 Mev (66.9%)


Half-value layer = 1.7 mm of lead

Limits

Ring dosimeter required for work with >1 mCi

10 half lives: 1 years

Sink disposal:

  • 1500 uCi/month
  • 50 uCi/day*

* Average amount

Safety Precautions

Follow General Precautions for working with radioactive material.
Store in shielded containers.
Whole body and ring badges are required for work with Cr-51.
Minimize exposure with lead shielding.
Use GM detector or liquid scintillation counter to detect Cr-51.
Urinanalysis is required within 24 hours after working with 100 mCi or greater of Cr-51.
Dispose of radioactive waste in accordance with requirements in the Radiation Safety Manual.
 

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Equipment Suppliers   Dose Information for Cr-51

For a 1 mCi point source the exposure rate at 1 cm is 200 mR/hour

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