Physical Characteristics

  • Half-life: 14.3 days
  • Emissions: Beta particles with a maximum energy of 1.71 MeV and an average energy of 0.7 MeV.
  • Maximum Range: 620 cm in air; 0.8 cm in tissue; 0.6 cm in plexiglas
  • Fraction transmitted through the dead layer of the skin: 0.95

Dose Rate and Shielding

  • Dose rate to the skin at 10 cm: 4070 mrad/hour/mCi (for an unshielded point source)
  • Dose rate to epidermal basal cells from skin contamination of 1 mCi/cm2: 9200 mrad/hour
  • Shielding: 3/8” plexiglas/lucite will shield all P-32 betas. For high activity sources exceeding a few millicuries, it may be desirable to add lead shielding outside the plexiglas shielding to shield against bremsstrahlung x-rays. Plexiglas should be placed closest to the P-32 source as primary shielding, and lead should be used outside the plexiglas as secondary shielding.
  • Annual Limit on Intake (ALI): 600 microcuries via ingestion. The intake of one ALI will produce a dose of 5 rem.


A G-M detector will readily detect low-level P-32 contamination, although liquid scintillation counting is also an acceptable method for detecting removable P-32 contamination.


High localized doses are possible while handling millicurie amounts of P-32 and as a result of skin contamination. Reduce doses by wearing safety glasses (for shielding the eyes), using remote handling tools such as tongs, using shielding extensively to shield storage and experimental containers and work areas, and performing thorough and frequent surveys of the work area, clothing and the body.

Radiation Monitoring Requirements: Radiation monitoring badges must be worn by any person who uses open sources of P-32 in amounts of 5 mCi or more for extended operations (applies to most operations other than simple aliquoting from a stock vial).

Waste Disposal

  • Solid Wastes: through the Onsite Decay-in-Storage Program
  • Liquid Scintillation Wastes:  through the Off-Site Radioactive Waste Disposal Program
  • Liquid Wastes: through the Sewer Disposal Program. The laboratory disposal limit for P-32 is 0.3 mCi per month.