HP-27: P-32

Shielding

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.

Detection

A tiny drop of contamination of P-32 can be easily detected with a Geiger Counter.

Equipment/Supplies

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

Safety Rules

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

Post-Use Procedures

• 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 rso@wpi.edu
• If any contamination is found on your hands, wash thoroughly with soap and water
• Contact the RSO at rso@wpi.edu 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 rso@wpi.edu 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

Decay Rates

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

Other Information

Physical Data

• 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)

Radiological Data

• 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

Shielding

• 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

Survey Instrumentation

• 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

General Precautions

• 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