APPENDIX D: Maximum Permissible Doses and Concentrations

Dose Limits (top)

• The maximum permissible doses as established by "10 CFR Part 20" are as follows:

• State of New Jersey dose limits for state-licensed radioactive materials and radiation-producing machines vary slightly from federal limits. For more information contact the Office of Environmental Health and Safety or consult the New Jersey Administrative Code 7:28-6.
• To the extent practicable, procedures and controls which are based on sound radiation protection principles must be used to achieve occupational doses and doses to members of the general public that are not only below the dose limits specified above but are as low as reasonably achievable (ALARA).

Pregnant Workers (top)

1. The Nuclear Regulatory Commission (NRC) has issued regulations which mandate the separate control of fetal dose when a pregnant worker submits a written declaration of pregnancy to her supervisor. In some cases adequate control of fetal dose may require that the pregnant worker be reassigned to a different position or that her job responsibilities be modified. To protect the worker’s employment or for any other reason, a pregnant worker may choose not to declare her pregnancy. If a written declaration of pregnancy is not submitted to the employer, then the worker’s dose continues to be controlled under the normal dose limits for radiation workers. The following points summarize the NRC's fetal dose regulations:

• The fetal dose regulations apply only to a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception.
• The dose to the fetus resulting from occupational exposure of a declared pregnant worker may not exceed 500 mrem for the entire pregnancy,
• If the dose to the fetus has exceeded 450 mrem by the time a woman declares her pregnancy, the total additional dose to the fetus for the rest of the pregnancy must not exceed 50 mrem.
• The dose received by the fetus over the course of the pregnancy should be delivered at a reasonably uniform rate; the rate of exposure should avoid substantial variation.
• Monitoring (personnel monitors and/or bioassays, as appropriate) shall be provided for any declared pregnant woman who is likely to receive a dose in excess of 10 percent of the dose limits specified above.

2. To comply with NRC regulations, Princeton University has established a Declared Pregnant Worker Program which is available to all pregnant radiation workers. It is the responsibility of a pregnant radiation worker to decide whether to formally declare the pregnancy to Princeton University for the purpose of controlling radiation exposure to the unborn baby.

• In order to make a declaration of pregnancy, a pregnant worker fills out EHS-HP Form #406, "Declaration of Pregnancy", and either submits it directly to her supervisor or sends the Declaration directly to the Office of Environmental Health and Safety. Copies of the form are available from the Office of Environmental Health and Safety and are included in the prenatal radiation information packet which is distributed to all female radiation workers.
• When a written declaration of pregnancy is received by the Office of Environmental Health and Safety, a "Health Physicist" meets with the declared worker and the worker’s supervisor to discuss exposure history, job responsibilities, and research protocols in order to assess the dose the baby has received and is likely to receive. The "Health Physicist" will work with the worker and the worker’s supervisor to recommend changes, if necessary, to job duties or research protocols. For the type of radiation work performed at Princeton University, it is rarely necessary to recommend reassignment or changes to job duties.
• The "Health Physicist" completes a fetal dose worksheet which becomes part of the worker’s permanent dose history. The "Health Physicist" reviews dose reports for declared pregnant workers as the reports are received.
• The fetal dose limit will stay in effect until the declared pregnant worker:

1) Is known to be no longer pregnant

2) Informs the Office of Environmental Health and Safety that she is no longer pregnant

3) Informs the Office of Environmental Health and Safety that she is withdrawing her Declaration of Pregnancy.

• No action will be taken to control fetal dose unless a written Declaration of Pregnancy has been submitted to the Office of Environmental Health and Safety.

"Unrestricted Areas" (top)

Radiation levels in excess of the following are not permitted in "Unrestricted Areas":

• Radiation levels which, if an individual were continuously present in the area, could result in a dose to the individual in excess of two millirems in any one hour
• Radiation levels which, if an individual were continuously present in the area, could result in a dose to individual in excess of 100 millirems in any consecutive days
• Radiation levels which could result in an individual receiving a dose in excess of 100 millirems in one calendar year.

Medical Exemptions (top)

None of the limits in this appendix are to be interpreted as applying to the intentional exposure of patients to radiation for the purpose of diagnosis or therapy.