5730 Years



Beta Energy

156 keV

Travel distance

  • Air: 24 cm or 10 inches
  • Water/Tissue: 0.28mm or 0.012 inches ( ~1% of 14C betas transmitted through dead skin layer, i.e. 0.007 cm depth)
  • Plastic: 0.25mm or 0.25 inches

Annual Intake Limit

  • Inhalation: 2000 µCi
  • Ingestion: 2000 µCi


  • Portable Survey Meters:
    • Geiger-Mueller [~10% efficiency];
    • Beta Scintillator [~5% efficiency]
  • Wipe Test: Liquid Scintillation Counting is the best readily available method for counting 14C wipe tests


None required – mCi quantities not an external radiation hazard

Dosimeter Monitoring

  • Urine bioassay is the only readily available method to assess intake [for tritium, no intake = no dose].
  • After any accident/incident in which an intake is suspected please provide urine sample for analysis.


  • Avoid skin contamination [absorption], ingestion, inhalation, & injection [all routes of intake].
  • Many 14C compounds readily penetrate gloves and skin; handle such compounds remotely and wear double gloves, changing the outer pair at least every 20 minutes.


  • Wipe test of work areas and equipment surfaces and count them in a Liquid Scintillation Counter.
  • Monitor surfaces routinely and keep records of the results. A GM probe may detect 14C if the probe is used within a ½ inch of the surface and the proper probe is used.
  • Dispose the waste as per USC radiation waste policies. Do not mix the waste with any other isotope.

Radiological Data

  • Radiotoxicity:
    • 0.023 mrem/uCi of 14CO2 inhaled;
    • 2.09 mrem/uCi organic compounds inhaled/ingested
  • Critical Organ:
    • Fat tissue [most labeled compounds]; bone [some labeled carbonates]
  • Exposure Routes:
    • Ingestion, inhalation, puncture, wound, skin contamination absorption
  • Radiological Hazard:
    • External Exposure – None from weak 14C beta
    • Internal Exposure & Contamination – Primary concern