The University of Iowa

Radionuclide Safety Guideline for P-33

Physical Data

  • Radiation: Beta (100% abundance)
  • Energy: Max 248.5 keV; Average 76.4 keV


  • Physical: 25.3 days
  • Biological: Bone ~ 1155 days; Whole Body ~ 257 days
  • Effective: 25.3 days


  •  50 cm in air unshielded

External Hazard

  • Not an external hazard

Internal Hazard

  • Critical Organ: Bone (soluble); Lung (Inhalation); GI Tract (Ingestion - insoluble compounds)

Skin & Eye Hazard

  • Avoid skin contamination.

Safety Guidelines 

  • Plexiglas 1 cm thick is recommended as shielding material. Thinner Plexiglas, although adequate to reduce exposure, does not have good mechanical properties.
  • Dosimeters cannot detect P-33 beta radiation due to its low energy.
  • Wear a lab coat and disposable gloves when working with P-33. Change gloves frequently.
  • Avoid direct eye contact - work behind a Plexiglas shield or wear safety glasses.
  • P-33 can often be substituted in an assay already using P-32. However, due to the difference in beta energy, you should increase exposure time approximately four-fold for P-33 according to the vendor's technical data specifications. 

Update 1/2013