Radionuclide Safety Data Sheets

Phosphorus - 32(32P)


Beta Energy: 1710 keV (maximum)
694 keV (average)(100%)

Physical Half-Life: 14.3 days
Biological Half-Life: 1155 days (Bone) / 257 days (Whole Body)
Effective Half-Life: 14.1 days (Bone) / 13.5 days (Whole Body)
Specific Activity: 285,518 curies / gram
Maximum Beta Range in Air: 610.00 cm = 240 inches = 20 feet
Maximum Beta Range in Water / Tissue: 0.76 cm = 1/3 inch = 0.35 inch
Maximum Range in Plexiglas / Lucite / Plastic: 0.61 cm ~ 3/8 inch ~ 0.38 inch
Half-Value Layer (HVL): 0.076 cm (water / tissue)

NOTE: (1) A beta particle with an energy of 795 keV can penetrate to a depth of the lens of the eye (0.3 cm or 30 mg/cm2).
(2) A beta particle with an energy of ≥ 70 keV is required to penetrate the dead layer of skin.
(3) Although the maximum range of a P-32 beta particle is 0.8 cm in tissue/water, approximately 50% are absorbed in the first 0.1 cm of tissue/water.
(4) Approximately 7% of the P-32 beta particles that expose the surface of the eye can actually penetrate to the depth of the lens of the eye (0.3 cm or 30 mg/cm2).
(5) Rule of Thumb:
• 1 MeV betas can penetrate approximately 10 ft in air
• 1 MeV betas can penetrate approximately 0.4 cm of tissue/H2O

* [Fraction of P-32 beta particles transmitted through the dead layer of skin (7 mg/cm2 or 0.007 cm thick) = 95%]



  • Critical Organ (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)
  • Internal & external exposure and contamination are concerns with P-32.

Committed Dose Equivalent (CDE):
(Organ Doses)
32 mrem/uCi (ingested)
37 mrem/uCi (puncture)
96 mrem/uCi (inhaled / Class W / lungs)
22 mrem/uCi (inhaled/Class D/bone marrow)
Committed Effective Dose Equivalent (CEDE):
(Whole Body)
8.33 mrem/uCi (ingested / WB)
5.55 mrem/uCi (inhale/Class D)
12.50 mrem/uCi (inhale/Class W)
Annual limit on Intake (ALI): 600 uCi (ingested / all compounds)
900 uCi (inhalation / except phosphates)
400 uCi (inhalation / phosphates)

* [1.0 ALI = 600 uCi ingested (all compounds) = 5,000 millirem CEDE / WB]


Skin Contamination Dose Rate (Basal): 5,867 mrem/hour per 1 uCi/cm2

  • Localized Dose Rate to Basal Cells at 7 mg/cm2 or 0.007 cm tissue depth (without air reflection)
  • Very HIGH localized dose received if P-32 contamination remains of skin!

Skin Contamination Dose Rate (Extremity Skin): 4770 mrem/hour per 1 uCi/cm2

  • Bone receives approximately 20% of dose ingested or inhaled for soluble P-32 compounds.
  • Tissues with rapid cellular turnover rates show higher retention due to concentration of phosphorus in the nucleoproteins.
  • P-32 is eliminated from body primarily via urine.

Phosphorus Metabolism: 30% is rapidly eliminated from body
40% has a 19-day biological half-life
30% is reduced by radioactive decay
60% of P-32 (ingested) is excreted from body in first 24-hours; only about 1% per day is excreted after the 2nd or 3rd day.

SHIELDING: > 3/8" thick plexiglass / acrylic / lucite / plastic / wood

* [DO NOT use lead foil or sheets! Penetrating bremsstrahlung x-rays will be produced!]
* [Use lead sheets or foil to shield bremsstrahlung x-rays and only AFTER low density plexiglass / acrylic / lucite / wood shielding]


  • Use G-M survey meter and, preferably, a pancake/frisker probe (15.5 cm2 surface area). Counting efficiency is approximately 25% for P-32.
  • Low-energy NaI probe only used to detect bremsstrahlung x-rays
  • Liquid scintillation counter (indirect counting) should be used to detect removable surface contamination of P-32 on smears or swabs.

PERSONAL RADIATION MONITORING DOSIMETERS (Whole Body and Finger Tabs): REQUIRED when handling > 5.0 millicuries of P-32 at any time.

Dose Rate from an unshielded 1.0 millicurie isotropic point source of P-32:

Distance mrad/hour
1.00 cm 200,000.0
15.24 cm 860.0
10.00 ft 2.2

Surface dose rate from 1.0 uCi/ml P-32 (in water) is approximately 1480 mrem/h.


Derived Air Concentration (DAC):
4.0E-7 uCi/mL (all except phosphate)
2.0E-7 uCi/mL (phosphates)
Airborne Effluent Release Limit:*
(Annual Average)
1.0E-9 uCi/mL (all except phosphate)
5.0E-10 uCi/mL (phosphates)

* Applicable to the assessment & control of dose to the public (10 CFR 20.1302). If this concentration was inhaled or ingested continuously over one year it would produce a TEDE of 50 millirem.

  • Urinalysis: Not required; however, may be requested by RSS personnel after a radioactive spill of P-32 or a suspected intake.
  • Unrestricted Area Removable Contamination Limit: 1,000 dpm / 100 cm2
  • Container Labeling Requirement [10 CFR 20.1905]: ≥ 10 uCi


  • Inherent Volatility (STP): Insignificant / Negligible
  • P-32 is used as a tracer to study phosphorus-containing processes (nucleotide biochemistry).
  • Skin (0.007 cm) & lens of the eye (0.3 cm) are primary dose concerns.
  • Skin contamination (skin dose), lens of the eye dose, ingestion, inhalation, puncture, absorption through skin, and area contamination are primary radiological concerns.
  • Drying can cause airborne P-32 dust contamination.
  • Rapid boiling can cause airborne P-32 contamination.
  • Expelling P-32 solutions through syringe needles and pipette tips can generate airborne aerosols.
  • Never work directly over an open container of P-32. Avoid direct eye exposure from penetrating P-32 beta particles.
  • Always wear a lab coat and disposable gloves when handling P-32.
  • Monitor your hands, shoes, lab coat, work areas, and floors using a survey meter equipped with a thin-window G-M probe for gross contamination. Preferably, use a sensitive G-M pancake / frisker probe (15.5 cm2 monitoring area).
  • Monitor for removable surface contamination by smearing, swiping, swabbing, or wipe testing where P-32 is used. Count smears or swabs in a liquid scintillation counter (LSC).
  • Use low-atomic (low Z) shielding material to shield P-32 and reduce the generation of bremsstrahlung x-rays. The following materials are low Z materials: plexiglass, acrylic, lucite, plastic, wood, or water.
  • DO NOT use lead foil, lead sheets, or other high-density (high atomic number) materials to shield P-32 directly. Penetrating bremsstrahlung x-rays will be generated in lead and other high density shielding material.
  • Percent of incident P-32 betas converted to bremsstrahlung x-rays: 4.8% (lead), 0.5% (lucite), and 0.3% (wood).
  • Safety glasses or goggles are recommended when working with P-32.
  • Typical liquid scintillation counter counting efficiency for P-32 (full window / maximum) ≥ 85%.
  • Typical detection limit of P-32 in urine specimens using a liquid scintillation counter = 1.08E-7 uCi/ml.