Physical Characteristics

  • Half-life: 47 days
  • Emissions:
    • Beta particles: 0.210 MeV maximum energy (100 %) and 0.070 MeV average energy.  Beta Maximum Range: 34 cm in air; 0.04 cm in tissue; 0.04 cm in plexiglas
    • Gamma rays: 0.279 MeV (100%).

Dose Rate and Shielding

  • Dose rate to the skin at 30 cm: 15.2 mrem/hour/mCi (for an unshielded point source)
  • Gamma Dose rate (deep tissue dose) at 30 cm: 1.63 mrem/hour/mCi (for an unshielded point source)
  • Dose rate to epidermal basal cells from skin contamination of 1 µCi/cm2: 3296 mrem/hour
  • Shielding: Shield stock vials with lead.
  • Half-Value Layer: 0.2 cm lead (The half-value layer is the amount of material required to reduce the radiation intensity by 50%.)
  • Annual Limit on Intake (ALI): 500 microcuries via ingestion and 800 microcuries via inhalation. The intake of one ALI will produce a dose of 5 rem. 


A G-M detector will readily detect low-level Hg-203 contamination, although a wipe survey using liquid scintillation counting is also an acceptable method for detecting removable contamination.


High localized doses are possible while handling millicurie amounts of Hg-203 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 Hg-203 in amounts of 0.5 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 Hg-203 is 3 mCi per month.