Radiation Exposure
Any release of radioactive material is a potential source of radiation exposure to the population. In addition to exposure from external sources, radiation exposure can occur internally from ingesting, inhaling, injecting, or absorbing radioactive materials. Both external and internal sources may irradiate the whole body or a portion of the body.
Radiation affects people by depositing energy in body tissue, which can cause cell damage or cell death. In some cases there may be no noticeable effect. In other cases, the cell may survive but become abnormal, either temporarily or permanently, and may become malignant. Both large and small doses of radiation can cause cellular damage.
The extent of the damage depends on:
- type of radiation involved,
- the total amount of energy absorbed,
- the duration of exposure,
- dose rate of the exposure, and
- the particular organs exposed.
By damaging the genetic material (DNA) contained in the body's cells, radiation can cause cancer. Damage to genetic material in reproductive cells can cause genetic mutations that can be passed on to future generations. In rare occurrences where there is a large amount of radiation exposure, sickness or even death can occur in a limited amount of hours or days.
When it comes to ionizing radiation, remember time, distance, and shielding:
- Minimize time spent in areas with elevated radiation levels. Minimizing the exposure time reduces a worker's dose from the radiation source.
- Maximize distance from source(s) of radiation. A worker's radiation dose decreases as the worker's distance from the source increases. For gamma rays and X-rays, the radiation intensity is inversely proportional to the square of the distance from the source (i.e., the inverse square law). This means increasing the distance by a factor of 2 decreases the dose rate by a factor of 4.
- Use shielding for radiation sources (i.e., placing an appropriate shield between source(s) of radiation and workers). Inserting the proper shielding (e.g., lead, concrete, or special plastic shields depending on the type of radiation) between a worker and a radiation source will greatly reduce or eliminate the dose received by the worker.
An ionizing radiation protection program should include, at a minimum:
- Qualified staff (e.g., RSO, health physicist) to provide oversight and responsibility for radiation protection policies and procedures.
- ALARA stands for As Low As Reasonably Achievable (ALARA). It is a guiding principle in radiation protection used to eliminate radiation doses that have no direct benefit.
- A dosimetry program in which personal exposure monitoring is conducted, as required by federal or state regulations, for external dose and, as needed, for internal dose.
- Surveys and area monitoring to document radiation levels, contamination with radioactive materials, and potential worker exposures.
- Radiological controls, including entry and exit controls, receiving, inventory control, storage, and disposal.
- Worker training on radiation protection, including health effects associated with ionizing radiation dose, and radiation protection procedures and controls to minimize dose and prevent contamination.
- Emergency procedures to identify and respond to radiological emergency situations. (OSHA's Radiation Emergency Preparedness and Response page also provides information about this topic.)
- Recordkeeping and reporting programs to maintain all records and provide dosimetry reports and notifications, as required by federal or state regulations.
- Internal audit procedures to annually audit all aspects of the radiation protection program.
OSHA's Ionizing Radiation standards protect workers in general industry (29 CFR 1910.1096), construction (29 CFR 1926.53), shipyard employment (29 CFR 1915.57 and, to the extent it applies, 29 CFR 1910.1096), marine terminals (29 CFR 1910.1096, to the extent it applies), and longshoring (29 CFR 1910.1096, to the extent it applies).
Knowledge Check Choose the best answer for the question.
2-6. Radiation can cause cancer by _____.
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