Radionuclide Fact Sheet

Symbol: ³³P

States/Forms: Soluble

Physical Characteristics

• Radioactive Half Life (T_½): 25 days
• Decay Type: Beta^- (ß^-)
• Maximum Energy Emission: 0.249 MeV
• Maximum Range in Air: 49 cm
• Maximum Range in Water/Tissue: 0.06 cm
• Maximum Range in Plexiglas or Lucite: 0.05 cm

Hazard Category

• A Level (High Hazard): >1 Ci
• B Level (Moderate Hazard): >20 mCi to 1 Ci
• C Level (Low Hazard): 0.1 mCi to 20 mCi

Radiological Characteristics

• 40% of beta particle energy transmitted through dead layer of skin.
• Critical organs: Bone marrow – 30%; Body tissues – 70%
• Routes of intake: Ingestion, inhalation, puncture, wound, skin contamination (absorption).
• Internal exposure and contamination: Primary radiological concerns with ³³P.
• External exposure: Minimal concern for ³³P.

Dosimetry

• Film badges and dosimeter rings are not appropriate for monitoring ³³P exposure.

Bioassay Requirements

• Urinalysis may be required after spills or incidents of contamination.

External Radiation Hazards and Shielding

• There is minimal external hazard with ³³P, i.e. the glass vial containing the ³³P provides sufficient shielding from the beta particles, however lucite or plexiglas may be used as shielding.  If the skin is uniformly contaminated with ³³P, 1 microcurie/cm² (Ci/cm²) will deliver a dose of 3200 miilirems per hour (mrems/hr) to the basal skin cells.

Hazards if Internally Deposited

ALI (Annual Limit of Intake):

• 4000 μCi – by ingestion
• 6000 μCi – by inhalation

DAC (Derived Air Concentration):

• 3 x 10^-6 μCi/mL

Survey Instrumentation

• A Geiger-Muller survey detector with a pancake/frisker probe can be used to detect ³³P.  The counting efficiency for ³³P is approximately 6%.
• Liquid scintillation counters should be used to detect removable surface ³³P contamination using smears or swabs.

Problems and Precautions