Guidance Info
Bioassay Guidelines
Recommended Bioassay Levels
Bioassay's are performed to monitor internal exposures to radioactive materials. The table below lists recommended levels for the more popular isotopes. If you use this amount (activity) of a radionuclide in one month, contact the RPO for more information about bioassays.
| Isotope | Physical Form | Recommended Bioassay Level (mCi/month/person) |
Type of Bioassay |
| 14C | Liquid | 1,700 | Urine sample |
| 3H | Liquid | 670 | Urine sample |
| 125I | Volatile | 0.33 | Thyroid count |
| 131I | Volatile | 0.25 | Thyroid count |
| 32P | Liquid | 500 | Urine sample |
| 33P | Liquid | 2,500 | Urine sample |
| 35S | Liquid | 1,700 | Urine sample |
| 35S | *Volatile | 170 | Urine sample |
* Methionine, cysteine or trans-labeled 35S have the potential to be slightly volatile.
Email radiation_protection at harvard dot edu to send comments and suggestions to the Radiation Protection Office
