Health Physics

Tritium Exposure: Guidance for Medical Professionals

Last Updated: January 26, 2026
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Tritium is a naturally occurring, radioactive form of hydrogen found in small amounts in the environment. In the event of an exposure, medical providers may need to treat patients exposed to tritium and administer time-sensitive tests. Tritium cannot be detected by any handheld radiation detectors.

Sources of Manmade Tritium

  • Glow-in-the-dark items like some exit signs, watches, key chains and jewelry.
  • Certain military equipment, such as weapon sights and compasses.​

If you are a user of tritium devices, review the Tritium: Facts and Safety​ page.

Critical Test Timing

Tritium distributes throughout the body's water quickly, follows the same pathways as body water with a small amount (~3%) bound to organic molecules, and reaches equilibrium in the body in about 2 hours. For times less than about 30 days after an intake, tritium is removed exponentially from the body with a half-life of about 10 days.  So, tritium urine bioassay must be performed relatively soon after a suspected intake.​

Importance of Accurate Specimen Collection

To ensure accurate test results, follow these guidelines:

  • Wait 4 Hours Post-Exposure: Tritium needs time to distribute uniformly in the body. Specimens collected earlier may not reflect accurate Tritium levels.
  • Discard Early Voids: Urine present in the bladder immediately after exposure may dilute Tritium levels.
  • Timing for Equilibrium: It takes about 2 hours for Tritium to equilibrate, but waiting 4 hours ensures reliable testing.

Steps for Collecting a Tritium Urine Specimen

Follow these steps for proper specimen collection after exposure:

  1. Discard the first void: Ensure this happens within 2 hours of exposure.
    • If voiding is not possible, proceed with appropriate measures to ensure voiding occurs.
    • Document any issues in the laboratory request and memorandum for priority analysis.
  2. Discard additional voids: Avoid collecting specimens during the 4-hour waiting period.

Specimen Collection Guidelines

A medical treatment facility should be able to assist.

  1. Wash hands before handling collection materials.
  2. About 50 to 100 milliliters of urine is needed.
  3. Use leak-proof polyethylene bottles. A 125 mL bottle is recommended.
  4. Follow the shipping procedures recommended by the analytical laboratory. For procedures, see the following documents.
    1. ​Defense Centers for Public Health – Aberdeen. 2023. Technical Guide 211, Radiobioassay Collection, Labeling, and Shipping Requirements​.
    2. Air Force Research Laboratory. 2016. U.S. Air Force School of Aerospace Medicine Laboratory Sampling and Analysis GuideExternal Link​.

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