d. Probability of a large acute dose
What is important to understand is that it takes a large acute dose of radiation
before any physical effect is seen. These acute doses have occurred in
Hiroshima/Nagasaki, and in a few radiation accidents, including Chernobyl. The
on the job is extremely low. Typically, radioactive materials are handled in small
quantities that do not produce a large amount of radiation. Where there is a
potential for larger exposures, many safety features are required.
2. Chronic radiation doses
A chronic radiation dose is typically a small amount of radiation received over a long
period of time. An example of a chronic dose is the dose we receive from natural
background every day of our lives. The body's cell repair mechanisms are better able
to repair a chronic dose than an acute dose.
a. The body has time to repair damage because a smaller percentage of the cells need
repair at any given time.
b. The body also has time to replace dead or non-functioning cells with new, healthy
3. Biological effects of radiation exposure
Somatic effects refer to the effects radiation has on the individual receiving the dose.
Genetic effects refer to mutations due to radiation damage to the DNA of a cell. When
this change is in the DNA of parental reproductive cells, it is called a heritable effect.
a. Somatic Effects
Somatic effects can best be described in terms of prompt and delayed effects as
1) Prompt Effects
Although rare in the nuclear industry, large doses are typically acute
radiation doses representing serious overexposures. The biological effects
of large acute doses are as follows: