injuries and poisoning
Radiation Injury
Contamination vs. irradiation
An individual's radiation dose can be increased in two ways, contamination and irradiation. Many of the most significant radiation accidents have exposed people to both. Contaminationis contact with and retention of radioactive material, usually as a dust or liquid. External contamination is that on skin or clothing, from which some can fall or be rubbed off, contaminating other people and objects. Internal contamination is radioactive material deposited within the body, which it may enter by ingestion, inhalation, or through breaks in the skin. Once in the body, radioactive material may be transported to various sites, such as the bone marrow, where it continues to emit radiation, increasing the person's radiation exposure, until it is removed or emits all its energy (decays). Internal contamination is more difficult to remove than external contamination. Irradiationis exposure to radiation but not to radioactive material, that is, no contamination is involved. A common example is diagnostic x-rays, used, for example, to evaluate a broken bone. Radiation exposure can occur without direct contact between people and the source of radiation (such as radioactive material or an x-ray machine). When the source of the radiation is removed or turned off, irradiation ends. People who are irradiated but not contaminated are not radioactive, that is, they do not emit radiation, and their dose from that source of radiation does not continue to increase. The average person in the United States receives about the same dose of naturally occurring radiation as that from manufactured sources of radiation (almost all of which is medical radiation used to diagnose or treat disease). 