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Introduction

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.

Concerns

  • 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

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

DAYS ELAPSED DECAY FACTOR
0 1.00
1 0.953
2 0.908
3 0.865
4 0.824
5 0.785
6 0.748
7 0.712
8 0.678
9 0.646
10 0.616
11 0.587
12 0.559
13 0.532
14 0.507
15 0.483
16 0.460
17 0.438
18 0.418
19 0.398
20 0.379
21 0.361
22 0.344
23 0.328
24 0.312
25 0.297
26 0.283
27 0.270
28 0.257
29 0.245
30 0.233
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

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