Risk associated with exposure to ionizing radiation

Question 1

Define Health Risk

Answer 1

Something that may endanger health

Question 2

two types of models

Answer 2

Absolute risk model- assumes radiation induces a crop of cancers over and above the natural incidence and is unrelated to it

relative risk model- assumes the effect of radiation is to increase the natural incidence at all ages after exposure by a given factor.

Monitoring personnel allows Navy to determine relative risk.

Question 3

organizations that developed the cancer risk estimates

Answer 3

1. United Nations Scientific Commitee on effects of Atomic Radiation (UNCEAR)

Committee of the U.S National Academy of sciences known as biological effects of ionizing radiation. (BIER)

Produce data that is used by other organizations in the world to create radiation protection standards

Question 4

Radiation doses received by workers in the Naval Nuclear Propulsion Program and commercial power plants.

Answer 4

Navy operated 71 nuclear powered submarines, 11 nuclear powered aircraft carriers, and three moored training ships.

occupational radiation exposure- Personnel assigned to tenders, bases, and nuclear-powered reactors

Most recent data ( yellow book )

Question 5

List three types of cancer vs dose response models

Answer 5

Linear no-threshold, linear-quadratic, hormesis

Linear no-threshold- suggest that any increase in dose results in an incremental increase in risk.

Linear-quadratic model- best model of cellular survival. Best fit to leukemia data.

hormesis- conjecture that low level of ionizing radiation, helps immunize cells against DNA damage. Very difficult to prove

Question 6

Which cancer vs dose response model is the basis for radiation protection limits

Answer 6

Linear- no threshold dose response models forms the basis for radiation protection limits.

Question 7

Why is there no dose limits for medical procedures

Answer 7

Federal regulation exempts medical exposure. Judgement that the benefit of patient justifies the radiation

Question 8

Organization Involved with radiation protection

Answer 8

1. International Commission on Radiological Protection ( ICRP)
   Makes recommendation international level, radiation protection
2. International Commission on Radiological units and measurement. (ICRU)
3. National Council on Radiation Protection and Measurement (NCRP)
4. Nuclear Regulatory Commission (NRC)
   Licensing of reactors, nuclear materials. reactor operators, low level waste sites.
5. Agreement States- State that enter into legal contract with NCR in which they assert their willingness and competence to regulate the safe use of radiation. Do not have authority to regulate federal facilities or nuclear reactors. Agreement states must provide at least as much protection as NRC regulation.

EPA- enforcement of regulation related to environment

US food and drug- Regulates design and manufacturing of radiation emitting products

Question 9

References available to student for individual counseling

Answer 9

Regulatory Guide 8.29- Instruction concerning risks from occupational radiation exposure

Regulatory guide 8.13 Instruction concerning prenatal radiation exposure

US Navy Radiological Controls Manuals appendix M
NNPP

Occupational Radiation Exposure from U.S Naval Nuclear Plants and their support. (Yellow Book)
summarizes radiation exposure to navy and civilian personnel monitored for radiation exposure

Question 10

Cancer risk estimate from exposure to ionizing radiation

Answer 10

Risk of fatal cancer from exposure to 1 rem of ionizing radiation is 4 x 0.04

risk of cancer incidence is increased from 20% to 20.04 from 1 rem of exposure