EH&S administers the personnel monitoring program for radiation workers at Iowa State University. The program includes dosimetry devices and bioassay analyses based on regulatory guidance from the Iowa Department of Health and Human Services.

Occupational dose limits

Current limits for occupational radiation exposure have been established at levels that, in light of present knowledge, will: (1) prevent acute radiation effects (erythema, epilation) and (2) limit the risks of late effects, such as cancer or genetic damage, to very low, “acceptable” levels. These limits can be found in Title 10, Part 20 of the Code of Federal Regulations, and Chapter 136C of the Iowa Administrative Code. These limits are based on external, internal, and external-plus-internal exposures. 

The table below summarizes external and internal exposure annual occupational dose limits.

Annual occupational dose limits
Limit rem* Sievert (sv)
Shallow Dose Equivalent, Whole Body 50 0.5
Shallow Dose Equivalent, Max. Extremity 50 0.5
Eye Dose Equivalent to the Lens of the Eye 15 0.15
Total Organ Dose Equivalent 50 0.5
Total Effective Dose Equivalent 5 0.05

*rem = the common unit of dose equivalent. Sievert is the S.I. dose equivalent unit. (100 rem = 1 sievert)

Dose limits to declared pregnant workers

Because of the increased susceptibility of the human embryo and fetus to damage from ionizing radiation, the National Council on Radiation Protection and Measurement (NCRP) recommends that the whole-body radiation dose received by a female worker during the nine months of her pregnancy not exceed 500 millirem (mrem) (5 mSv), or 10% of the annual occupational dose limit. 

  • Proper dosimeter use

    Dosimeters are issued to monitor your occupational dose. Review the factsheet below for information on the use, storage, and return of dosimeters.