Facebook Twitter LinkedIn Syndicate. Minus Related Pages. Mild symptoms may be observed with doses as low as 0. The dose usually must be external i. Radioactive materials deposited inside the body have produced some ARS effects only in extremely rare cases. The radiation must be penetrating i. High energy X-rays, gamma rays, and neutrons are penetrating radiations.
The entire body or a significant portion of it must have received the dose 3. Most radiation injuries are local, frequently involving the hands, and these local injuries seldom cause classical signs of ARS. The dose must have been delivered in a short time usually a matter of minutes. Fractionated doses are often used in radiation therapy. These are large total doses delivered in small daily amounts over a period of time.
Fractionated doses are less effective at inducing ARS than a single dose of the same magnitude. The three classic ARS Syndromes are: Bone marrow syndrome sometimes referred to as hematopoietic syndrome the full syndrome will usually occur with a dose between 0. The survival rate of patients with this syndrome decreases with increasing dose. The primary cause of death is the destruction of the bone marrow, resulting in infection and hemorrhage.
Gastrointestinal GI syndrome: the full syndrome will usually occur with a dose greater than approximately 10 Gy rads although some symptoms may occur as low as 6 Gy or rads. Survival is extremely unlikely with this syndrome.
Destructive and irreparable changes in the GI tract and bone marrow usually cause infection, dehydration, and electrolyte imbalance. The radiation will begin to destroy the cells in the body that divide rapidly. Because reproductive tract cells divide rapidly, these areas of the body can be damaged at rem levels as low as Long-term, some radiation sickness victims will become sterile.
These include: The size of the dose amount of energy deposited in the body The ability of the radiation to harm human tissue Which organs are affected The most important factor is the amount of the dose - the amount of energy actually deposited in your body.
Dose rem Effects Possible late effects; possible chromosomal damage. Hair The losing of hair quickly and in clumps occurs with radiation exposure at rems or higher. Brain Since brain cells do not reproduce, they won't be damaged directly unless the exposure is 5, rems or greater. Thyroid Certain body parts are more affected by exposure to different types of radiation sources than others. Blood System When a person is exposed to around rems, the blood's lymphocyte cell count will be reduced, leaving the victim more susceptible to infection.
Heart Intense exposure to radioactive material at 1, to 5, rems would do immediate damage to small blood vessels and probably cause heart failure and death directly. Like alcohol intoxication levels, levels of exposure to radioactivity due to radioactivity deposited in the body depend on a person's weight. A diagnostic tracer of one microcurie of radioactive calcium 45, given orally, would result in an exposure of 3.
Therapeutic radiation treatment that is delivered by administering radioactive material via the mouth or by injection usually results in high, very localized doses to a small part of the body, which absorbs most of the radioactivity.
The radioactivity concentrates and remains in the target organ for example, the thyroid for a longer period of time than does the radioactivity that is distributed to the rest of the body. The radiation exposure for other parts of the body is a function of the amount of radioactivity per pound and the time the radioactivity is present in the tissue.
For example, a hyperthyroid problem such as that experienced by former President George Bush is typically treated with a radioactive iodine drink designed to deliver about 10,, millirems of radioactive iodine to the thyroid. It would coincidentally deliver a dose to the rest of the body of about 20, millirems. A slightly lower dose of radioactivity is used for cancerous tumors.
Radiation to kill a cancerous tumor often involves a beam delivering 6,, millirems to the cancerous tissue, but the whole-body equivalent dose is much less, as it was in the thyroid example cited above.
What is a lethal dose from a single instance of radiation? According to studies made after the atomic bomb explosions in at Hiroshima and Nagasaki, half of the people died whose entire bodies were exposed to , millirems of radiation from the atomic bomb. All persons died whose bodies were exposed to , millirems of radiation.
This also was the annual occupational limit for adults from World War II through Limit changed in to 5, millirems. It is "as low as reasonably achievable; however, not to exceed 5, millirems.
An embryo or a fetus of a pregnant worker exposed to radiation a new regulation as of Jan. Potassium is an essential dietary element that is present mostly in the muscles. A localized dose delivers 10,, millirems to the thyroid and about 20, millirems to the rest of the body. Clearly, in the case of accidents such as at Chernobyl and Fukushima the situation is much less well controlled. Doses of around 30mSv were received by the , people living in settlements close to Chernobyl before the 30km-radius exclusion zone was evacuated days later.
In the case of Fukushima evacuation up to 20km from the power plants was much faster. Much higher doses up to mSv were received by some clean-up workers after Chernobyl, and little is known yet about doses to clean-up workers at Fukushima. If recent reports of doses up to 2. To cause death within hours of exposure to radiation, the dose needs to be very high, 10Gy or higher, while Gy will kill within 60 days, and less than 1.
However all doses, no matter how small, carry a finite risk of cancer and other diseases. This cancer risk may persist for the remainder of life but is unlikely to appear before at least years after exposure.
On this basis some 30, to 60, cancer deaths worldwide, but mainly in Europe, will have been caused by the Chernobyl accident, and many still remain to occur.
Much discussion is made of the so-called low dose problem. Effects from doses of less than 50mSv are difficult to assess directly due to the high background of spontaneous naturally occurring cancer, so it has been necessary to extrapolate down from measurements of effects at higher doses.
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