The occurrence of particular health effects from exposure to
ionizing radiation is a complicated function of numerous factors
- Type of radiation involved. All kinds of ionizing radiation can produce health effects. The
main difference in the ability of alpha and beta particles and Gamma and X-rays
to cause health effects is the amount of energy they have. Their energy
determines how far they can penetrate into tissue and how much
energy they are able to transmit directly or indirectly to tissues.
- Size of dose received. The higher the dose of radiation received, the higher the likelihood of health effects.
- Rate the dose is received. Tissue can receive larger
dosages over a period of time. If the dosage occurs over a number
of days or weeks, the results are often not as serious if a similar
dose was received in a matter of minutes.
- Part of the body exposed. Extremities such as the hands or
feet are able to receive a greater amount of radiation with less
resulting damage than blood forming organs housed in the torso. See radiosensitivity page for more information.
- The age of the individual. As a person ages, cell division
slows and the body is less sensitive to the effects of ionizing
radiation. Once cell division has slowed, the effects of radiation
are somewhat less damaging than when cells were rapidly dividing.
- Biological differences. Some individuals are more sensitive
to the effects of radiation than others. Studies have not been
able to conclusively determine the differences.
The effects of ionizing radiation upon humans are often broadly
classified as being either stochastic or nonstochastic. These two terms are discussed more in the next few pages.