Nutrino 50 April, 2002

Allowable Doses to

Radiation Workers, Minors, Embryo/Fetus, and Unrestricted Areas

• The following table provides the regulatory occupational limits for radiation workers. Doses to radiation workers who are minors under 18 years of age cannot exceed 10 percent of the limits.

*Effective dose equivalent. A measure of the amount of energy deposited by charged particles
in the tissue of interest.
**Seivert. 1 Seivert = 100 rem

• The dose to an embryo or fetus during the entire pregnancy, from occupational exposure of a woman who informs her employer of the estimated date of conception, is limited to 0.5 rem. If occupational circumstances make a dose to the embryo or fetus unavoidable, the dose should not exceed 0.05 rem per month. When a woman declares her pregnancy but does not provide an estimated date of conception, the dose to the embryo or fetus is limited to 0.05 rem per month.
• The dose in any unrestricted area such as public areas, offices, and corridors adjacent to radiation laboratories or X-ray facilities must not exceed 0.002 rem in any one hour.

Dosimetry in the Real World of NU

• Many years of observation show us that the vast majority of radiation workers at NU do not receive doses of significance; reports for those workers who wear dosimeters average much less than 1% of the limits.
• We are required to submit dosimetry reports for minors to IDNS; be sure to notify ORS of such workers.
• ORS encourages pregnant workers to declare their pregnancy so we can develop a dosimetry plan. The information is confidential.
• ORS can provide area monitors to measure the dose in public areas.
• Know the type of radiation emitted by the materials or sources you work with and use appropriate strategies of time, distance, and shielding to keep doses As Low as Reasonably Achievable (ALARA).
• Limit occupational dose by surveying often for contamination and cleaning it up as soon as you find it. It is not easy to equate a level of contamination to dose; suffice it to say that keeping the lab clean is the best approach.