Also found in: Dictionary, Thesaurus, Medical, Legal, Wikipedia.
radiation sickness,harmful effect produced on body tissues by exposure to radioactive substances. The biological action of radiation is not fully understood, but it is believed that a disturbance in cellular activity results from the chemical changes caused by ionization (see ionion,
atom or group of atoms having a net electric charge. Positive and Negative Electric Charges
A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
..... Click the link for more information. ). Some body tissues are more sensitive to radiation than others and are more easily affected; the cells in the blood-forming tissues (bone marrow, spleen, and lymph nodes) are extremely sensitive. Radiation sickness may occur from exposure to a single massive emanation such as a nuclear explosion (such as Hiroshima and Nagasaki), or it may occur after repeated large exposure or to even very small doses in a plant or laboratory, since radiation effects are cumulative. Moreover, exposure to the ultraviolet radiationultraviolet radiation,
invisible electromagnetic radiation between visible violet light and X rays; it ranges in wavelength from about 400 to 4 nanometers and in frequency from about 1015 to 1017 hertz.
..... Click the link for more information. of the sun can cause tissue destruction and trigger mutations that can lead to skin cancerskin cancer,
malignant tumor of the skin. The most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Rarer forms include mycosis fungoides (a type of lymphoma) and Kaposi's sarcoma.
..... Click the link for more information. . Radiation sickness may be fairly mild and transitory, consisting of weakness, loss of appetite, vomiting, and diarrhea. Since even in a mild dose of radiation the blood-forming tissue is destroyed to some extent, there is a reduction in the supply of blood cells and platelets. This increases the tendency to bleed and reduces the body's defense against infection. After a massive dose of radiation the reaction may be so severe that death quickly ensues. This is usually due to severe anemia or hemorrhage, to infection, or to dehydration. Extremely high doses damage the tissues of the brain, and death usually follows within 48 hr, as was demonstrated at ChernobylChernobyl
, Ukr. Chornobyl, abandoned city, N Ukraine, near the Belarus border, on the Pripyat River. Ten miles (16 km) to the north, in the town of Pripyat, is the Chernobyl nuclear power station, site of the worst nuclear reactor disaster in history. On Apr.
..... Click the link for more information. . There is no treatment for radiation sickness, although it is sometimes possible for persons to survive otherwise lethal doses of radiation if bone marrow transplants are performed. Potassium iodide is to protect against thyroid cancer from radiation exposure, but the drug should ideally be taken four hours prior to the exposure. Exposure to radiation can cause genetic mutation; the progeny of those subjected to excessive radiation tend to show deleterious genetic changes. The genetic damage from the atomic bombs dropped on Japan is still evident and such damage will continue to surface in people directly affected by the nuclear diasaster at Chernobyl. Persons working with radioactive materials or X rays protect themselves from excessive exposure to radiation by shields and special clothing usually containing lead. Processes involving radioactive substances are observed through thick plates of specially prepared glass that exclude the harmful rays. A dosimeter, a device measuring the amount of radiation to which an individual has been exposed, is always worn by persons working in radioactive areas.
a pathological condition caused by various kinds of ionizing radiation.
Human beings, animals, microorganisms, and plants are constantly subjected to gamma irradiation from the earth’s crust and to cosmic rays. In addition, traces of radioactive substances (40K, 226Ra, 222Rn, 14C) are found within the organisms themselves. Radiation sickness occurs only when the total dose of radiation begins to exceed the natural radiation background. The capacity of radiation to cause radiation sickness varies with the biological effect of the ionizing radiation: the larger the absorbed dose, the more pronounced the injury.
In man. Radiation sickness in man may be caused by external sources (radioactive contamination of the biosphere) or by irradiation from within the body (the radioactive substances entering with inhaled air or through the gastrointestinal tract or skin). It may result from comparatively uniform irradiation of the entire body or from the irradiation of a given organ or part of an organ. Acute radiation sickness, resulting from a single wholebody exposure at comparatively high doses (hundreds of rads), is distinguished from chronic radiation sickness, which can proceed from the acute form or can be a consequence of chronic exposure to low doses (several rads).
The general clinical symptoms of radiation sickness depend chiefly on the total dose of radiation. Observations have shown that a single wholebody exposure of up to 100 rads produces comparatively mild, transitory changes, regarded as premorbid. Doses of more than 100 rads cause various forms of radiation sickness (of the bone marrow or intestines, for example) of varying severity, in which both the main symptoms and the outcome depend chiefly on the extent to which the hematopoietic organs are involved. Single wholebody doses of more than 600 rads are considered absolutely lethal; victims die within a month or two after exposure.
In the most typical form of acute radiation sickness, with doses of more than 200 rads, primary reactions (nausea, vomiting, and general weakness) begin to appear within minutes or hours. Symptoms subside after three or four days, and an apparently healthy stage ensues. However, careful clinical examination reveals that the sickness has progressed. This stage lasts from 14-15 days to four or five weeks, after which the general condition deteriorates, the feeling of weakness increases, hemorrhages occur, and the body temperature rises. As a result of the involvement of the hematopoietic organs, the leukocyte count in the peripheral blood decreases steadily (after a temporary increase) and reaches extremely low levels (a condition called radiation leukopenia), predisposing the patient to sepsis and hemorrhage. This stage lasts two or three weeks.
There are other forms of radiation sickness. For example, whole-body irradiation at doses ranging from 1,000 to 5,000 rads gives rise to the intestinal form of the condition, which is characterized primarily by involvement of the intestine. Eventually, the water-salt balance is disturbed, owing to severe diarrhea, and the blood circulation is impaired. A patient suffering from this form of radiation sickness usually dies within days, bypassing the ordinary stages of the condition. After whole-body doses of more than 5,000 rads, death occurs within one to three days, or even during the exposure itself, from injury to brain tissues (as in cerebral radiation sickness). Other forms of radiation sickness are a function mainly of the site of irradiation.
The course of the disease and the degree of damage in radiation sickness can depend on individual sensitivity and age. Even small doses may cause severe injury in children and the very old, who are less resistant to radiation. Because the tissues are especially sensitive to radiation during embryonic development, irradiation of pregnant women (for example, in radiotherapy) is undesirable even at low doses.
The body recovers quickly after irradiation at moderate doses. Pronounced symptoms may be absent in the mild forms of radiation sickness; in the more severe forms, full recovery sometimes takes a year or more. Long-term effects include infertility in women and absence of spermatozoa (azoospermia) in men, although these changes are often temporary. Opacification of the lens, or radiation cataracts, sometimes develops months or even years afterward. Neurotic symptoms and focal disturbances of circulation sometimes persist after recovery from acute radiation sickness. Sclerotic changes, malignant neoplasms, or leukemia may develop, and congenital abnormalities may appear in the offspring.
A protracted and phasic course of disease is characteristic of chronic radiation sickness. This is a result of the manifestations of the injury, on the one hand, and the regenerative and adaptive reactions of the body, on the other. Even if an organ or tissue is deeply injured, the systemic reaction can be indistinct and delayed. The main symptoms in the early stages of chronic radiation sickness include numerous disturbances in the nervous regulation of the visceral functions and especially of the cardiovascular system. Changes may occur in enzymic activity and gastrointestinal secretion and motility. Impairment of the physiological restoration of hematopoiesis results in leukopenia. All symptoms are exacerbated as the radiation exposure time is increased and as the disease progresses.
The treatment of acute radiation sickness is directed at normalizing the hematopoietic organs by transplanting bone marrow, giving blood transfusions, and administering nucleic acid preparations and hematopoietic stimulants; at controlling infection with antibiotics; at preventing hemorrhage with vitamins; at diminishing intoxication by bloodletting and the use of blood substitutes; and at directly influencing the nervous system. Persons suffering from chronic radiation sickness are prescribed a diet rich in proteins and vitamins, extended exposure to fresh air, and exercise therapy. Symptomatolytic agents are used to normalize the activity of the heart, neurons, and gastrointestinal tract. When hematopoiesis is affected, hematopoietic stimulants are recommended.
The maximum permissible doses and concentrations of radioisotopes have been set by law for various industrial and occupational groups at a total of no more than 5 rads per year—a dose that does not endanger persons handling the radioactive substances. Danger of irradiation may arise from the violation of work safety regulations, from accidents, or from the wartime use of atomic weapons. Atomic blasts sharply increase contamination of the environment by the products of radioactive fission —radioactive iodine (111I), strontium (90Sr), cesium (137Cs), carbon (14C), and plutonium (239Pu). Atomic blasts increase the incidence of congenital defects. In such cases, shielding against the ionizing radiation will prevent radiation sickness.
REFERENCESKireev, P. M. Luchevaia bolezn’. Moscow, 1960.
Kraevskii, N. A. “Ostraia luchevaia bolezn’.” In Mnogotomnoe rukovodstvo po patologicheskoi anatomii, vol. 8 [book 2]. Moscow, 1962.
Kurshakov, N. A. “Luchevaia bolezn’.” In Mnogotomnoe rukovodstvo po vnutrennim bolezniam, vol. 10. Moscow, 1963.
Radiatsionnaia meditsina, 4th ed. Moscow, 1968.
Krotkov, F. G. Chelovek i radiatsiia. Moscow, 1968.
Lindenbraten, L. D. Meditsinskaia radiologiia. Moscow, 1969.
P. D. GORIZONTOV
In animals. Radiation sickness has been most thoroughly studied in domestic mammals and poultry. There are two forms of radiation sickness in animals: acute and chronic. The acute form is the result of a single whole-body exposure to 150-200 rads (mild), 200-400 rads (moderate), 400-600 rads (severe), or more than 600 rads (extremely severe). Depending on the severity of the course of the disease, animals may exhibit listlessness, loss of appetite, vomiting (in swine), thirst, diarrhea (possibly with mucus and blood), temporary elevation of body temperature, shedding of hair (in dogs), mucosal hemorrhage, weakened cardiac activity, lymphopenia, or leukopenia. In addition, if the course of the disease is extremely severe, unsteady gait, muscular spasms, diarrhea, and death occur. Recovery is possible if the course of the disease is mild or moderate.
Chronic radiation sickness develops after prolonged exposure to low whole-body doses of gamma radiation or with the entry of radioactive substances into the body itself. The results of such exposure include a gradual weakening of cardiac activity, endocrine dysfunction, inanition, and decreased resistance to infection.
Before beginning treatment, the animals are removed from the contaminated site and the radioactive substances are washed from the skin and fur with water and detergents. The transfusion of blood or blood substitutes and the intravenous injection of 25-40 percent glucose with ascorbic acid are recommended at the onset of the disease. If the animals were contaminated through the alimentary tract an adsorbent is used, such as an aqueous mixture of bone meal or barium sulfate with potassium iodide. If contamination occurred through the lungs, expectorants are prescribed.
In the event of internal exposure, the radioactive substances are excreted and contaminate the environment. They may also enter the human body in such foods as milk, meat, and eggs. Products from animals exposed to radiation should not be eaten by man or fed to wild animals, since these products can induce radiation sickness.
REFERENCEZashchita zhivotnykh i rastenii ot oruzhiia massovogo porazheniia. Minsk, 1968.
A. S. KOSENKO
In plants. Radiation sickness in plants results from exposure to various kinds of ionizing radiation, the most dangerous being alpha particles and neutrons, which disturb the metabolism of nucleic acids, carbohydrates, and fats. Roots and young tissues are highly sensitive to irradiation. A common symptom is retarded growth. For example, in young wheat, bean, and corn plants, growth begins to slow 20 to 30 hours after exposure to more than 400 rads. Specific, varietal, and individual intravarietal differences in radiosensitivity have been determined. For example, the symptoms of radiation sickness in Tradescantia appear after exposure to 40 rads, and in gladioli after 6,000 rads. The lethal dose for most higher plants is 2,000-3,000 rads, and for lower plants (for example, yeasts), 30,000 rads. Affected plants should not be eaten by man or fed to cattle, since they may induce radiation sickness. Methods of protecting plants against radiation sickness have not yet been developed.
REFERENCEVasil’ev, I. M. Deistvie ioniziruiushchikh izlucheniina rasteniia. Moscow, 1962.
M. S. DUNIN