Phosphorus-32 is a commonly used radionuclide with a half-life of 14.3 days, emitting beta particles with a maximum energy of 1.71MeV. The beta particles travel a maximum of 20 feet in air.
- Surface radiation exposure to the skin of the hands
- A drop of contamination containing 1 microcurie of P-32 on 1 cm2 area of the skin produces an exposure of 2,000 mrem/hour
- Radiation exposure in air over an open vial
- The dose rate at the opening of a vial containing 1 mCi of P-32 can be as high as 26000 mrem/hour
Plexiglass (lucite) is the best shield for beta particles from P-32. When more than 1 mCi of P-32 is handled, a sufficient number of x-rays (bremstrahlung) may be formed to require lead foil to be added to the exterior of the shield. The beta particles travel a maximum of 3.1 mm in glass, 6.7 mm in lucite, and 8 mm in tissue.
A tiny drop of contamination of P-32 can be easily detected with a Geiger Counter.
The following equipment and supplies must be available:
- A Geiger Counter sensitive to beta particles
- A plexiglass benchtop shield.
- Disposable latex or plastic gloves.
- Film badge and ring badge.
- Full-length lab coat.
- Plexiglass containers for radioactive waste.
- Pipettes dedicated to the use of P-32.
- Plastic safety glasses.
- Commercial decontaminate
If the following safety rules are followed, personnel radiation exposure will be as low as reasonably achievable.
- Designate a specific area of the lab for P-32 handling
- Place the plexiglass shield near a wall (not toward another work area on the other side of the bench) away from the main flow of traffic in the lab
- All persons in the laboratory must wear a whole body film badge when in the lab, even those who are not handling P-32
- All persons handling P-32 must wear a ring badge on the hand which is most frequently used to handle vials, samples, pipettes, etc. containing P-32
- Full-length lab coats must be worn by all persons who handle P-32
- Protect the skin of your hands from becoming contaminated by wearing two pairs of disposable gloves
- A Geiger counter must be in operation during the experiment, and preferably at all other times
- To avoid contaminating the detector, place a thin sheet of plastic (i.e., Saran Wrap) around the detector
- Place all vials and test tubes containing P-32 behind a plexiglass shield
- Check the radiation level in front of the shield to determine if Lead foil should be added to block out the x-rays (called bremstrahlung) formed by the beta particles interacting with the plexiglass
- Do not work directly over an open container of P-32
- Never pipette 32P by mouth
- Only use pipettes which have been dedicated to your specific use of P-32
- Pipettes will easily become contaminated and therefore, should not be shared with others
- Use the Geiger Counter to check your gloves frequently for contamination
- If contamination is found, immediately dispose of the gloves in the radioactive waste container
- Use the Geiger Counter to check your hands, shoes, clothing, work bench, floor, centrifuges, and water baths for contamination
- If any contamination is found on your shoes and/or clothing, contact the RSO at firstname.lastname@example.org
- If any contamination is found on your hands, wash thoroughly with soap and water
- Contact the RSO at email@example.com for assistance
- If any contamination is found on the work bench, floor, or lab equipment, use a commercial radiation contamination remover with paper towels to clean up the equipment
- Place the towels in the radioactive waste receptacle
- If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is P-32, maximum cpm found, and the date you measured the level
- If contamination cannot be removed from the floor, contact the RSO at firstname.lastname@example.org to obtain shielding materials
- Inform your fellow lab workers if any unremovable contamination is found
- Check the normal trash container to make sure no radioactive waste has been accidentally placed there
- Store the waste temporarily in plexiglass containers or other containers which are sufficient to absorb P-32 beta particles
- Wash your hands thoroughly after using P-32
|DAYS ELAPSED||DECAY FACTOR|
|143||(10 half-lives) 0.001|
For example, if your vial contained 250 uCi of P-32 on 07 Aug 98, the amount of activity remaining on 19 Aug 98 (12 elapsed days) would be:
Activity x Decay Factor = 250 uCi x 0.559 = 139.75 uCi
- Beta energy: 1.709 MeV (maximum)
- 0.690 MeV (average, 100% abundance)
- Physical half-life: 14.3 days
- Biological half-life: 1155 days
- Effective half-life: 14.1 days (bone) /13.5 days (whole body)
- Specific activity: 285,000 Ci/g
- Maximum range in air: 610 cm
- Maximum range in water/tissue: 0.76 cm
- Maximum range in plexiglas/lucite/plastic: 0.61 cm
- Half-Value Layer (HVL): 2.00 mm (water/tissue)
- Critical organ (biological destination) (soluble forms): Bone
- Critical organs (insoluble forms or non-transportable P-32 compounds): Lung (inhalation) and G.I. tract/lower large intestine (ingestion)
- Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption)
- External and internal exposure from P-32
- Committed Dose Equivalent (CDE): 32 mrem/mCi (ingested), (Organ Doses) 37 mrem/mCi (puncture), 96 mrem/mCi (inhaled/Class W/lungs), 22 mrem/mCi (inhaled/Class D/bone marrow)
- Committed Effective Dose Equivalent (CEDE): 7.50 mrem/mCi (ingested/WB), 5.55 mrem/mCi (inhale/Class D), 13.22 mrem/mCi (inhale/Class W)
- Skin contamination dose rate: 8700-9170 mrem/mCi/cm2 (7 mg/cm2 or 0.007 cm depth in tissue)
- Dose rate to basal cells from skin contamination of 1.0 mCi/cm2 (localized dose) 9200 mrad/hr
- Bone receives approximately 20% of the dose ingested or inhaled for soluble P-32 compounds
- Tissues with rapid cellular turnover rates show higher retention due to concentration of phosphorous in the nucleoproteins
- P-32 is eliminated from the body primarily via urine.
- Phosphorus metabolism
- 780,000 mrad/hr at surface of 1.0 mCi P-32 in 1 mL liquid
- 26,000 mrad/hr at mouth of open vial containing 1.0 mL P-32 in 1.0 mL liquid
- 3/4" to 3/8" thick plexiglas/acrylic/lucite/plastic/wood
- Do NOT use lead foil or sheets! Penetrating Bremsstrahlung x-ray will be produced!
- Use lead sheets or foil to shield Bremsstrahlung x-rays only after low density plexiglas/acrylic/lucite/wood shielding
- GM survey meter and a pancake probe
- Low-energy NaI probe is used only to detect Bremsstrahlung x-rays
- Liquid scintillation counter (indirect counting) may be used to detect removable surface contamination of P-32 on smears or wipes
- Because it is a bone seeker, special precautions must be taken to minimize any chance of introducing into the body
- Airborne contamination can be generated through drying (dust), rapid boiling, or expelling solutions through syringe needles and pipette tips, due to aerosols
- Personnel radiation monitors (whole body and finger rings) are required when handling greater than 1.0 mCi of P-32 at any time
- Never work directly over an open container; avoid direct eye exposure from penetrating P-32 beta particles
- Always wear a lab coat and disposable gloves when handling P-32
- Monitor personnel work areas and floors using a GM survey meter equipped with a pancake (beta) probe, for surface contamination
- Monitor for removable surface contamination by smearing, or wiping where P-32 is used
- Use low-density (low atomic number) shielding material to shield P-32 and reduce the generation of Bremsstrahlung x-rays
- The following materials are low atomic number materials: Plexiglas, acrylic, lucite, plastic, wood, or water
- Do NOT use lead foil, lead sheets, or other high density materials (metals) to shield P-32 directly.
- Materials with atomic number higher than that of aluminum (Z =13) should NOT be used
- Penetrating Bremsstrahlung x-rays will be generated in lead and other high density shielding material
- Safety glasses or goggles are recommended when working with P-32
- Typical GM survey meter with pancake probe efficiency is greater than or equal to 45%
- Typical liquid scintillation counter counting efficiency for P-32 (full window/maximum) greater than or equal to 85%
- Typical detection limit of P-32 in urine specimens using a liquid scintillation counter = 1.1 x 10E-7 uCi/mL