Iodine Protects against Radiation from Nuclear Reactor Accidents

by | Mar 15, 2011




Currently, increasing amounts of radiation are escaping from nuclear power plants in Japan that were damaged by the recent 9.0 earthquake that hit Japan on March 10, 2011, and the tsunami that followed. Based on the best scientific information that we have, I do not believe that any significant amount of radiation from these reactors will reach populations the United States. Nevertheless, this points out the real concern that such an event could happen in the U.S.
Many of us hear in Phoenix and around the world do live near a working nuclear plants. Additionally, radiation exposure from other sources such as medical or, heaven forbid, terrorist attacks, could eventually affect some of us. The only proven product known to protect against Nuclear Radiation from a Nuclear Reactor Accident is Potassium Iodide. I have in the past recommended that every family have Potassium Iodide at home in there emergency medicine cabinet. This is a good time to be reminded that we would be smart to be prepared and keep a supply of Potassium Iodide and other emergency preparedness products on hand in case of an emergency.
Taking oral Potassium Iodide (KI) (50-100 mg in adults) up to 48 h before Radioactive Iodine exposure can almost completely block thyroid uptake and therefore greatly reduce the thyroid absorbed dose.
Potassium Iodide administration is even effective if administered after an exposure to radioactive iodine although the protection is diminished. Taking Potassium Iodide 2 or up to 8 hrs after Radioactive Iodine exposure yields protective effects of 80% and 40%, respectively.
For more information: Check out the research results for Potassium Iodide use in treating radioactive exposure listed below:
The use of iodine as a thyroidal blocking agent in the event of a reactor accident. Report of the Environmental Hazards Committee of the American Thyroid Association.
JAMA 1984 Aug 3;252(5):659-61
Becker DV, Braverman LE, Dunn JT, Gaitan E, Gorman C, Maxon H, Schneider AB, Van Middlesworth L, Wolff J.
In the event of a nuclear reactor accident, radioactive materials could be released into the environment: radioisotopes of iodine could constitute a major component of such a release. Upon such exposure, radioiodines could enter the body and accumulate in an unprotected thyroid gland where they would remain for varying periods of time. A number of methods have been proposed to protect those at risk of exposure. Administration of thyroid-blocking agents (such as potassium iodide) to exposed populations could be effective, but their use has raised a number of questions since there are considerable gaps in the scientific information available about the possible effects of low-level radiation from radioiodine. In addition, there are only limited data available about potential toxic side effects of potassium iodide distributed widely to large, unsupervised populations. Concern about these issues led the American Thyroid Association to appoint a committee of its members with special interest and competence in these areas to review the problems in detail and develop an advisory statement on the questions at issue for those to whom this matter might be of concern.
PMID: 6737670 [PubMed – indexed for MEDLINE]
Potassium iodide as a thyroid blocker–Three Mile Island to today.
DICP 1989 May;23(5):422-7
Halperin JA.
CIBA Consumer Pharmaceuticals, Edison, NJ 08837.
The Three Mile Island (TMI) nuclear emergency in the U.S. in March 1979 marked the first occasion when use of potassium iodide (KI) was considered for thyroid blocking of the population in the vicinity of a potentially serious release of fission products from a nuclear power reactor. In face of a demand that could not be satisfied by commercial supplies of low-dose KI drug products from the U.S. pharmaceutical industry, the Food and Drug Administration directed the manufacture and stockpiling of sufficient quantities of saturated solution of potassium iodide (SSKI) to provide protection for one million people in the event of a large-scale release of radioiodines. Although the drug was not used, the experience of producing, stockpiling, and making ready for use a large quantity of the drug resulted in significant public policy, regulatory, and logistical issues. A number of these issues have been resolved through scientific debate and consensus, development of official guidance regarding the proper role of KI in nuclear emergencies, and the approval of New Drug Applications for KI products specifically intended for thyroid blocking in nuclear emergencies. Other issues regarding broad-scale implementation of the guidelines remain today. This paper traces the history of the development and implementation of the use of KI from pre-TMI to the present.
PMID: 2471366 [PubMed – indexed for MEDLINE]
Potassium iodide for thyroid blockade in a reactor accident: administrative policies that govern its use.
Thyroid 1997 Apr;7(2):193-7
Becker DV, Zanzonico P.
New York Hospital-Cornell Medical Center, New York 10021, USA.
A marked increase in thyroid cancer among young children who were in the vicinity of the Chernobyl nuclear power plant at the time of the 1986 accident strongly suggests a possible causal relationship to the large amounts of radioactive iodine isotopes in the resulting fallout. Although remaining indoors, restricting consumption of locally produced milk and foodstuffs, and evacuation are important strategies in a major breach-of-containment accident, stable potassium iodide (KI) prophylaxis given shortly before or immediately after exposure can reduce greatly the thyroidal accumulation of radioiodines and the resulting radiation dose. Concerns about possible side effects of large-scale, medically unsupervised KI consumption largely have been allayed in light of the favorable experience in Poland following the Chernobyl accident; 16 million persons received single administrations of KI with only rare occurrence of side effects and with a probable 40% reduction in projected thyroid radiation dose. Despite the universal acceptance of KI as an effective thyroid protective agent, supplies of KI in the US are not available for public distribution in the event of a reactor accident largely because government agencies have argued that stockpiling and distribution of KI to other than emergency workers cannot be recommended in light of difficult distribution logistics, problematic administrative issue, and a calculated low cost-effectiveness. However, KI in tablet form is inexpensive and has a long shelf life, and many countries have large stockpiles and distribution programs. The World Health Organization recognizes the benefits of stable KI and urges its general availability. At present there are 110 operating nuclear power plants in the US and more than 300 in the rest of the world. These reactors produce 17% of the world’s electricity and in some countries up to 60-70% of the total electrical energy. Almost all US nuclear power plants have multistage containment structures with large steel and concrete shells and multiple redundancy of core cooling mechanisms. These successfully prevented the release of major amounts of radionuclides in the Three Mile Island partial loss-of-primary coolant accident in 1979. The Chernobyl accident, in a different type of reactor that is common in Eastern Europe, did not have effective outer shell containment and released almost 50 MCi of I131 compared to the 20 Ci of I131 released at Three Mile Island. Such accidents have precipitated extensive re-evaluation of the design and safety devices of all operating reactors. However, a major contributing factor to the accidents was human error and considerable efforts must be made to train plant operators so they have a better understanding of reactor operation and use of safety mechanisms.
PMID: 9133683 [PubMed – indexed for MEDLINE]
Effects of time of administration and dietary iodine levels on potassium iodide (KI) blockade of thyroid irradiation by 131I from radioactive fallout.
Health Phys 2000 Jun;78(6):660-7
Zanzonico PB, Becker DV.
Nuclear Medicine Service, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. [email protected]
Radioiodines, particularly 131I, may be released into the environment in breach-of-containment nuclear reactor accidents and localize in and irradiate the thyroid with an attendant risk of neoplastic growth and other adverse health effects. Pharmacologic thyroid blockade by oral potassium iodide (KI) (50-100 mg in adults) can substantially reduce thyroid uptake of and irradiation by internalized radioiodine. In the current analysis, computer modeling of iodine metabolism has been used to systematically elucidate the effects of two practically important but highly variable factors on the radioprotective effect of KI: the time of administration relative to exposure to radioiodine and the dietary level of iodine. In euthyroid adults receiving iodine-sufficient diets (250 microg d(-1) in the current analysis), KI administered up to 48 h before 131I exposure can almost completely block thyroid uptake and therefore greatly reduce the thyroid absorbed dose. However, KI administration 96 h or more before 131I exposure has no significant protective effect. In contrast, KI administration after exposure to radioiodine induces a smaller and rapidly decreasing blockade effect. KI administration 16 h or later after 131I exposure will have little effect on thyroid uptake and absorbed dose and therefore little or no protective effect. The 131I thyroid absorbed dose is two-fold greater with insufficient levels of dietary iodine, 2,900 cGy/37 MBq, than with sufficient levels of dietary iodine, 1,500 cGy/37 MBq. When KI is administered 48 h or less before 131I intake, the thyroid absorbed doses (in cGy/37 MBq) are comparably low with both sufficient and insufficient dietary iodine levels. When KI is administered after 131I intake, however, the protective effect of KI is less and decreases more rapidly with insufficient than with sufficient dietary iodine. For example, KI administration 2 and 8 h after 131I intake yields protective effects of 80 and 40%, respectively, with iodine-sufficient diets, but only 65 and 15% with iodine-deficient diets. In conclusion, whether exposed populations receive sufficient or insufficient dietary iodine, oral KI is an effective means of reducing thyroid irradiation from environmentally dispersed radioiodine but is effective only when administered within 2 d before to approximately 8 h after radioiodine intake.
PMID: 10832925 [PubMed – indexed for MEDLINE]

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