When a person is near a source of radiation, some type of radioactive material, he or she
can be exposed to the radiation emitted by this source. However, he or she does not become
contaminated.
One way to think about exposure is to think about X-rays. When a person has a chest X-ray,
he or she is exposed to radiation, but does not become contaminated with radioactive material.
A person can reduce his or her exposure to radiation, if he or she is shielded in some
ways from the radiation, for example, if the person is behind a concrete wall, or if the
radioactive source is inside of a lead container.
In order to become contaminated, radioactive material must get on the skin, or clothing,
or inside of the body. For example, if radioactive material is incorporated into a dirty bomb,
a conventional explosive, such as dynamite, that has been laced with radioactive material,
then people could become contaminated when the device is detonated. Radioactive material
on the outside of the body is called external contamination. When a person becomes externally
contaminated, simply removing the clothing can remove up to 90% of the contamination.
Gently washing the skin and the hair can remove most of the remaining contamination.
If a person ingests or inhales radioactive material, it can become incorporated in the
organs of the body. This is called internal contamination. When a person is internally
contaminated, depending on the type of radioactive material with which they were contaminated,
certain medications can be administered to speed up the rate at which the radioactive
material is eliminated from the body. Such medications include Prussian blue and DTPA.