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Dose Limits

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 Public Health.

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 also in Chapter 136C of the Iowa Administrative Code. These limits are based on external, internal, and external plus internal exposures. 

The table below provides a summary of the current annual occupational dose limits for external and internal exposures.

 Annual Occupational Dose Limits for Adult Workers

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.