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Appendix C: P-32 Information and Safe Handling Guide


Radioactive half-life 14.3 days
Decay mechanism Beta emission
Energy Emax = 1.709 MeV
Contamination monitoring Thin window Geiger Mueller detector
Dosimetry Film badge, TLD ring, urinalysis bioassay
Shielding 1 cm Lucite

  • The dose rate on contact on the side of 1 mCi delivery vial will be on the order of 1000 mrem/hr. If possible, avoid direct hand contact with vials and sources.
  • When working with 100 uCi or more of P-32, work should be done behind a 1 cm thick Lucite shield. If more than 1 millicurie of P-32 is used, lead foil should be added to the exterior of the shield because of the formation of x-rays by the high activity (bremstrahlung).
  • Beta particles from P-32 travel a maximum of 20 feet in the air.
  • One uCi of P-32 in direct contact with l cm2 of bare skin gives a dose rate to the skin of about 2000 millirem/hr. This means that the quarterly NRC limit of 7500 millirem to the skin would be reached in 3 hours and 15 minutes.
  • Radiation exposure in the air over an open vial containing 1 millicurie of P-32 can be as high as 26,000 millirem per hour. The quarterly NRC limit of 18,250 millirem for the hands would be reached in 42 minutes.
  • Always protect your skin when handling unsealed materials. Wear gloves, lab coats, and shoes.
  • A thin window G-M survey meter should always be available. A survey should be made immediately after use and any "hot spots" should be decontaminated.
  • Film badges may be required for P-32 work. Dosimetry rings may be worn for P-32 work, and are required when handling 1 millicurie or more.
  • Handle and store your radioactive waste carefully.

Safety Rules

  • Place the Plexiglas shield near a wall or in a hood away from the main flow of traffic.
  • Designate a specific area of the laboratory for all P-32 experiments.
  • All personnel who handle P-32 must wear full-length laboratory coats and safety glasses.
  • Personnel handling P-32 may wear a ring badge on the hand which is most likely to handle vials, samples, pipettes, etc., containing P-32.
  • A Geiger counter capable of detecting beta particles and secondary x-rays must be in operation during the experiment and preferably at all times. Place Saran Wrap around the counter to avoid contaminating the detector.
  • Check the radiation level in front of the shield to determine if lead foil should be added to block out bremstrahlung x-rays formed by the interaction of the beta particles with the Plexiglas or gamma radiation.
  • Check your gloves frequently with the counter to detect contamination. If contaminated, immediately dispose of the gloves in a Plexiglas receptacle labeled as radiation waste.
  • Do not work directly over an open container of P-32.
  • Many P-32 compounds readily penetrate gloves and skin. Wearing two pairs of gloves and changing the outer pair every 15 or 20 minutes will reduce the chance of contamination and absorption through the skin.
  • Pipettes dedicated for the use of P-32 should be used. These pipettes should not be used for other purposes as they are easily contaminated by P-32.

Laboratory Cleanup after Use

  • Use the Geiger counter to check your hands, shoes, clothing, all work areas, and equipment used. Check the floor at the area where the isotope was used. If your clothing is contaminated, it will have to be removed and stored until the radiation level decays to background.
  • If any contamination is found on your hands, wash thoroughly with soap and water. This will usually be sufficient to remove surface contamination. If it does not, contact the University Radiation Safety Officer for assistance.
  • If any contamination is found on the work area or equipment, use a commercial radiation contamination remover such as Count Off, with paper towels, to clean the contaminated area.
  • Place the contaminated paper towels in a Plexiglas receptacle labeled as radiation waste.
  • If the contamination cannot be removed, label the area or equipment as radioactive, noting the isotope, the date of contamination, and the maximum dpm found.
  • If any un-removable radiation is found, contact the University Radiation Safety Officer.
  • Check the normal trash container to ensure that no radioactive waste was placed there.
  • Store all radioactive waste in specially marked containers.
  • Send a Radiation Survey report to the University Radiation Safety Officer.

I-125 Decay Rate
Elapsed Time (days) % Remaining Activity Decay Factor
0 100.0 1.0
1 95.3 0.953
2 90.8 0.908
3 86.5 0.865
4 82.4 0.824
5 78.5 0.785
6 74.8 0.748
7 71.2 0.712
8 67.8 0.678
9 64.6 0.646
10 61.6 0.616
11 58.7 0.587
12 55.9 0.559
13 53.2 0.532
14 50.7 0.507
15 48.3 0.483
16 46.0 0.460
17 43.8 0.438
18 41.8 0.418
19 39.8 0.398
20 37.9 0.379
21 36.1 0.361
22 34.4 0.344
23 32.2 0.322
24 31.2 0.312
25 29.7 0.297
26 28.3 0.283
27 27.0 0.270
28 25.7 0.257
29 24.5 0.245
30 23.2 0.233
143 (10 half-lives) 0.1 0.001