Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter VII: Mass Causalties in Thermonuclear Warfare
United States Department of Defense
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Radionuclides within the body represent a state of either internal contamination or incorporation. In internal contamination, radionuclides reside in the respiratory and gastrointestinal tracts, and have not crossed the mucous membranes. In incorporation the radionuclide has been transported across mucous membranes, or the radionuclide has been injected or absorbed through the skin or a wound. Once radionuclides are incorporated, they are significantly more difficult to remove; consequently, internal contamination must be removed before it is incorporated. The treatment involves reducing the absorption and internal deposition and enhancing the excretion of the absorbed radionuclides. A number of important factors must be understood in assessing the hazards and therapy of incorporated radionuclides. These include absorption, excretion, concentration, biologic half life, and effective half-life. A definitive review of these factors and incorporated radionuclides is provided in Report No. 65 of the National Council on Radiation Protection and Measurements (NCRP). Blocking agents can enhance elimination of the radionuclide or decrease the quantity incorporated. After incorporation, chelating agents olragents that mobilize the radionuclides are much less effective. It should be obvious that the least incorporation will occur with early administration of the proper drug. Chelating agents bind metals into complexes, thus preventing tissue uptake and allowing urinary excretion. These agents were previously referred to with regard to CaDTPA and transuranic incorporation through a skin wound. A handy checklist is provided in the front of NCRP Report No. 65 for guidance in rapidly treating and preventing transuranic incorporation.
Blocking agents are chemicals that saturate a tissue with a nonradioactive element, thereby reducing the uptake of the radionuclide. Dilution of an isotope involves administering large amounts of a stable isotope so that the hazardous radioisotope is diluted. Incorporated radioiodine can be treated by either approach. Radioiodine is an especially important radionuclide because of the increasing number of potential sources of exposure in medicine, nuclear weapons, and nuclear reactors. A power reactor may contain 10-100 million curies of iodine-131. A loss-of-coolant accident releasing 1% of the radionuclide under the most adverse weather conditions could give an iodine-131 exposure of 500 cGy (R) to a child's thyroid at 75 km. Since most of a dose of radioiodine is taken up by the thyroid within several hours, rapid administration is necessary. Early administration is not the only requirement, however; since exposure from a reactor accident will continue for a period of time. Many recommendations have recently been made to prevent the uptake of radioiodine. A recommended protective dose of stable potassium iodide (Kl) for a person over 1 year of age is 130 mg per day, while a dose of 65 mg per day is recommended for children under 1 year of age.
A multitude of other radionuclides of potential importance should be encountered only rarely. Extensive guidance for these can be obtained from NCRP Reports No. 65 and 55 and the Manual on Early Medical Treatment of Possible Radiation Injury.
To reiterate, the first several hours after exposure to radionuclides is the best time to prevent uptake, whether by local removal, chelation, physiologic treatment, or limitation of absorption.
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