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Security of Radioactive Materials

See trigger levels for isotopes requiring special security measures.


Federal regulations mandate that all radioactive material must be “secured against unauthorized removal.” This means no unauthorized personnel can remove radioisotope source vial(s) without being questioned/challenged by staff or encountering a physical barrier.

Trigger levels

Using a risk-based approach, UC San Diego has set trigger levels for isotopes requiring particular attention to security. Trigger levels for reporting losses of material to the State are set at low levels (see table below).

These trigger level values are based on radiotoxicity of the isotope; the greater the radiotoxicity, the lower the reportable quantity.

Radioactive shipments received in the EH&S Services Lab will be labeled if they exceed the trigger level.

Trigger levels for 6 commonly used isotopes

Trigger levels for 6 commonly used isotopes

Isotope Activity (mCi)
H-3 10
C-14 1
P-33 1
S-35 1
P-32 0.1
I-125 0.01

Reporting Criteria

Report immediately if lost or improperly disposed radioactive material exceeds the trigger levels listed above:

  • Normal business hours (8:00 a.m. – 4:30 p.m.) contact EH&S at (858) 534-3660
  • After business hours (after 4:30 p.m.) contact UC San Diego Police Department at (858) 534-4357
If you have questions or comments, contact EH&S Radiation Safety, (858) 822-2494.

Notice: Refer to the Radiation Safety Manual (PDF) for a detailed description of the UC San Diego radiation safety program.