History of Potassium Iodide


EARLY FINDINGS Development. The value of KI as a radiation protective was first recognized in 1954 following a Pacific nuclear bomb test. Shifting winds blew radioactive fallout in an unexpected direction, contaminating two small atolls 150 miles away. Although residents were quickly evacuated, it was too late. Within 20 years, most of the island’s adult population, and all of its children, had developed some form of thyroid disease or cancer.Doctors studying the problem soon realized that radioactive iodine in the fallout had entered the island’s food and water supplies. It had been inhaled and ingested by the islanders and absorbed by their thyroid glands. Over the years it led to the steady, inevitable, development of cancer and other thyroid malfunctions. While the fallout had contained traces of other radioactive products, these had played little or no role.This understanding led experts to speculate that much of the danger from radiation might be eliminated if the absorption of radioiodine by the thyroid gland could be blocked. As a result, a search began for a class of drugs that later became known as "thyroid blocking agents."By 1957, scientists had concluded that potassium iodide represented an ideal thyroid blocking agent. This material had been used for years in other therapies, was known to be extremely safe, inexpensive, had a long shelf life, and could prevent 99% of the radioactive iodine in fallout from being absorbed.Initial Recommendations. Though KI was quickly recognized for its radio-protective value for civil defense programs, it was not until 1977 that there was real interest in the drug. That year, the National Council on Radiation Protection (NCRP), acting on recommendations of the American Physical Society’s Reactor Safety Committee, suggested that a far more compelling reason to produce KI was the development of nuclear power in the United States. As the NCRP noted: "Of the several possibilities…that could affect the public, the one causing greatest concern is the sudden release of radionuclides….An important constituent in such a release would be a number of isotopes of radioiodine which could affect large numbers of people soon after the incident’

In December, 1978, the US Food and Drug Administration, noting that KI provides "almost complete (greater than 90%) blocking of peak radioactive iodine," published a request in the Federal Register for the production and storage of the drug. But, in a pattern that was to be repeated for the next 20 years, the advice of medical authorities and independent experts was ignored, and no KI was obtained.Four months later, at Three Mile Island in Harrisburg, Pennsylvania, the US suffered its worst commercial nuclear power-plant accident.

brought the US closer to a nuclear catastrophe than ever before or since. Fearing iodine might escape, the emergency response authorities sent to TMI immediately ordered KI for possible distribution. But none was available, so in an unprecedented action, the FDA attempted to manufacture the drug. Tablets could not be produced in time, so raw potassium iodide was mixed with water to make a low-grade pharmaceutical. Difficulties were encountered in finding bottles and matching caps, and there was no time to prepare labeling or usage instructions. Worse, the solution began breaking-down in the bottles almost immediately, and officials later acknowledged that they had serious concerns about its safety due to its poor quality. However, faced with the possibility of millions of people being exposed to radioactive iodine without any protection whatsoever, authorities reasoned that poor KI was better than none, and decided to ship what they could. It took six days, and eventually 237,013 bottles were sent to the reactor site.

Three Mile Island

The accident was nearly over by the time the product arrived. It was stored (in secret, watched by an armed guard) in a Harrisburg warehouse while officials tried to figure out if--and how--to distribute it. Because the amount received was far less than what might be needed, emergency personnel expressed serious fears of the possibility of rioting should a distribution be attempted. Fortunately, though, the accident was contained, and no iodine was released. With relief, the FDA ordered the KI solution destroyed, and the incident faded from memory.

But it could have been different. Harrisburg lies west of New York and Washington, and had a major release occurred with easterly winds, large cities on the Atlantic coast could have received significant exposure. Later, estimates pointed to the possibility of more than 500,000 people suffering thyroid injury in the "worst-case" scenario.

The enormous danger posed by the unavailability of KI was apparent to the Presidential panel (the Kemeny Commission) that investigated the TMI accident. Their report to the nation noted:

"The greatest concern during the accident was that significant amounts of radioactive material (especially radioactive iodine) trapped within the plant might be released." COMMISSION RECOMMENDATION: "An adequate supply of the radiation protective (thyroid blocking) agent, potassium iodide for human use, should be available regionally for distribution to the general population…affected by a radiological emergency."

This recommendation was widely accepted by scientists. Even the NRC announced it would support KI stockpiling. The issue appeared closed.But the nuclear industry resisted the recommendations to stockpile KI. Fearing the drug’s availability would send a message that nuclear power was unsafe, industry groups argued that another serious accident was virtually impossible. Further, they claimed that even if one should occur, there could be no release of radioactive iodine. Surprisingly, they were supported in this position by the NRC, which was also worried about its reputation. Like the industry they regulated, the NRC was against any lessening of public confidence in nuclear technology, and despite their initial promises to support KI stockpiling, they chose to "study" the matter and wait for the memory of TMI to disappear. They studied KI for six years. Then, the agency broke its earlier promise to stockpile, reneged on its commitment, and formulated a policy that called mandatory KI stockpiling "not worthwhile."Instead, a policy emerged that was premised on the idea that it would be cheaper to let people develop cancer and treat them afterwards, than to use KI to prevent the disease in the first place. Essentially, the industry decided to protect itself instead of the people. The appalling disregard for the health of Americans inherent in this policy has not abated over time. It was recently summed-up by one State official who wrote that his agency "stands firmly behind its contention that hundreds of thousands of people live normal healthy lives without functioning thyroid glands."

Virtually no one challenged this policy or the reasoning behind it--until Chernobyl.


On April 26, 1986, the nuclear reactor at the Russian Chernobyl Nuclear Station exploded. It was the world’s worst nuclear power accident, and it scattered radioactive iodine over thousands of square miles throughout Europe. Fortunately, much of the affected area was sparsely populated, and even more fortunate was the fact that the Soviets had large stockpiles of KI available (from old civil defense supplies) which they distributed within hours to people living close to the reactor. As a result, people in the Pripyat region near Chernobyl were protected and there has been no increase in thyroid cancer in this area.

Farther away from the reactor, though, distribution was much less thorough. As a result, today, just 12 years later, over 11,000 known (and possibly many unknown) cases of a rare form of childhood thyroid cancer have appeared, and no one can predict the total when the disease peaks in the year 2010. In Poland, 18 million people were given KI following the accident, and thus far no increase in thyroid cancer related to Chernobyl has been seen.Chernobyl proved that massive accidents were possible, and that optimistic assumptions by the NRC and the nuclear industry that radioactive iodine could not escape were clearly wrong. Follow-up studies have also demonstrated that the decision by the Russian, Polish and other governments to administer stored KI had been correct, and that stockpiled KI, issued immediately after an accident was as valuable as the experts had predicted. This was unequivocally stated by the US Federal Emergency Management Agency (FEMA) in a study following Chernobyl, where they reported that,

"Although the accident occurred at 01:24…Russian authorities reported it would be impractical to wake people…The time from 02:00 to 08:00 was spent in emergency planning and obtaining and distributing KI tablets for issuance to individuals at 08:00. The Russians were apparently well prepared for large-scale distribution of KI tablets to the general public. …Thousands of measurements of I-131 (radioiodine) activity in the thyroids of the exposed population suggest that the observed levels were lower than those that would have been expected had this prophylactic measure not been taken. The use of KI by the Pripyat population in particular was credited with permissible iodine content (less than 30 rad) found in 97% of the 206 evacuees tested at one relocation center. It is also important to note that no serious side effects of KI use have been reported."

Other countries also took large amounts. In the Scandinavian countries, for example, where the governments had long kept stockpiles of the drug, a large amount of KI, some of it 10 years old, was quickly consumed. No increase in the rate of thyroid cancer due to Chernobyl have been reported.These actions undoubtedly saved hundreds of thousands from cancer and other thyroid problems. While the Soviets deserve criticism for many of their actions regarding the Chernobyl incident, their emergency response plans, and their provisions and preparation for the health and safety of their citizens, were noteworthy. By comparison, the US government’s actions at Three Mile Island, though well motivated, lacked supplies and planning; were confused; contradictory; and needlessly dangerous to millions of people.

But despite the Chernobyl experience, US policy makers continued to fight KI stockpiling, with the NRC making the baffling statement that, "The apparently successful use of KI by the Soviets does not alter the validity of US policy that …stockpiling KI for use by the general public should not be required."

Current Status

Over the years, the Nuclear Regulatory Commission has consistently made promises that would assure KI availability for all Americans. After Three Mile Island, for example, the NRC pledged to support a national stockpiling plan, and following the demonstrated evidence of KI's value at Chernobyl, the NRC agreed to require states to consider it in emergency response planning. Finally, in 1998, in a highly encouraging development, the NRC announced it would fund the purchase of KI for any state wishing to stockpile the drug.

But the Agency's actions suggest these promises will never be kept. While not disputing the value and health benefits of the product, individuals from the various Federal and State agencies that crafted the existing KI policy remain resolute in opposing stockpiling, fearing that this would have a negative effect on the public’s perception of nuclear power. "The continuing debate over … KI has served no useful purpose other than to unduly undermine the effectiveness of nearly two decades of sound radiological emergency planning and preparedness", claims the Director of Nuclear Safety in one large state. Another senior official, arguing that stockpiling is unnecessary because states are already permitted to offer KI, claims that changes to existing policy are not required, since "the current ‘Federal Policy on [KI] Distribution…’ provides sufficient guidance to state and local governments [on how and when to distribute KI]" ¾ while neglecting to mention that this policy is obviously worthless if there is no KI to distribute. The reality is that significant stockpiles of the product do not exist today, and are unlikely to exist in the near future. Despite claims of support by individual staff members and its Commissioners, the NRC seems curiously unable to overcome the objections to stockpiling by the nuclear industry-- which would have us believe emergencies are impossible. Instead, officially rejected statistics have been used to support seriously flawed conclusions, and promises to assure KI protection for all Americans have repeatedly been broken.In 1998, in an attempt to justify its general position on KI, the NRC issued a document in draft form entitled "Assessment of the Use of Potassium Iodide as a Public Protective Action During Severe Reactor Accidents", (NUREG-1633). It was an extremely important document—not for its conclusions (which virtually all experts rejected), but for its demonstration of the lengths the NRC was willing to go to discredit KI, even if this meant distorting the issue beyond recognition. For example…

1. In an astonishing omission, the report fails to mention that KI has been found "safe and effective" by the US FDA. Instead, through an out-of-context quotation, the author of NUREG-1633 implies that the FDA is worried about the safety of KI, and it fails to quote the FDA's published position that there are "not sufficient grounds to conclude, or even to suggest, a significant and quantifiable proportion of serious reactions [side effects to KI]. 2. To make its point that KI is unnecessary, worthless, or both, NUREG-1633 quotes, but then ignores, the conclusion by the World Health Organization, that: Evidence of a marked excess of thyroid cancer in young children [from Chernobyl] has now been established….Therefore this indicates that stable iodine prophylaxis [KI] would be beneficial, especially for young children, after nuclear accidents, 3 The report mentions that "other countries and major international organizations…endorse the use of KI" (and have national stockpiles) but it offers the interesting suggestion that this may be due to "cultural and legal differences…"4. In a clumsy attempt to confuse the issue, NUREG-1633 announces it will evaluate the use of KI only in the 10 mile Emergency Planning Zone (EPZ) surrounding a reactor. People outside the zone will not be given protection. Yet the government acknowledges that: the increase in cancer caused by Chernobyl …was detected in Belarus, Russia, and Ukraine. Notably, this increase, seen in areas more than 150 miles (300 km) from the site, continues to this day and primarily affects children who were 0-14 years old at the time of the accident….the vast majority of the thyroid cancers were diagnosed among those living more than 50 km (31 miles) from the site. 5. The author of the report makes a point of noting that KI only protects the thyroid from cancer. While true, nothing is made of the fact that Chernobyl showed that thyroid injury represents the greatest threat in an accident, though NUREG-1633 admits that: As of 1996, except for thyroid cancer, there has been no confirmed increase in the rates of other cancers including leukemia…attributed [to Chernobyl}. In addition, there is no evidence of any excess hereditary diseases in children born after the accident.

As a result of criticism of the biased nature of NUREG-1633, the NRC took the unusual step of withdrawing this report, and announced it would form a KI Task Force to study KI to arrive at recommendations for policy makers. But in an action that suggests that no change in the Agency's position can be expected, the author of NUREG-1633 was appointed Chairman of the Task Force.And, (as reported in the New York Times, of April 20, 1999), following the latest meeting of the Task Force, the NRC announced that it is withdrawing its 1998 promise to fund the purchase of KI. Therefore, in the event of an accident, Americans can expect that government provided KI will be unavailable, and most people will face radiation unprotected.

Or, one can purchase potassium iodide from Nukepills.com


To appreciate the US Nuclear Regulatory Commission's policy on KI, it is important to understand the estimates made in their document, Examination of the Use of Potassium Iodide (KI) as an Emergency Protective Measure for Nuclear Reactor Accidents. (NUREG/CR-1433, Sandia National Laboratories, Albuquerque, New Mexico, 1980).This report describes the health effects of a nuclear accident in detail, and provides casualty estimates at various distances from a reactor. Although the report is highly technical and difficult to read, buried in its pages of statistics is the acknowledgment that a "Core-Melt Atmospheric" accident (that is, an accident like Chernobyl which releases a large portion of the reactor core into the atmosphere) could threaten millions of people.NUREG-1433 points out that thyroid growths (nodules) and other thyroid damage would be expected to occur for hundreds of miles downwind after an accident through breathing. This is described in tables 3 and 4 of the report, as shown below:


Distance in Miles

Mean Thyroid Dose (REM) for Exposed Adult Outdoors

Probability of Thyroid Damage to Exposed Adult Located Outdoors

1 13,500 60% 5 5,800 70% 10 3,200 70% 25 1,100 40% 50 380 13% 100 100 3% 150 36 1% 200 16 0.5%

For children, increase dose and probability of damage by an approximate factor of two.  Weather conditions based on calculated probability distributions. Thyroid damage includes thyroid nodules (both benign and cancerous) and ablated thyroid.  Assumed risk coefficient of 334 thyroid nodules per million person-rem to the thyroid.  Includes inhalation dose only. Does not include ingestion.  Probabilities conditional on accident occurring.

But the NRC limits its accident planning to 10 miles. In other words, there is nothing to protect people who, for example, are 50 miles away, despite the probability that 13% of all exposed adults (and about a quarter of the children) at this distance could be injured. Yet use of KI would prevent this—a fact the NRC does not dispute. (See NRC notice regarding "radiation emergency potassium iodide" below.)



NRC INFORMATION NOTICE NO. 88-15: AVAILABILITY OF U.S. FOOD AND DRUG ADMINISTRATION (FDA)-APPROVED POTASSIUM IODIDE FOR USE IN EMERGENCIES INVOLVING RADIOACTIVE IODINE.Addressees: Medical, Academic, and Commercial Licensees who possess radioactive iodine.Purpose: This notice is intended to provide information on the storage and use of potassium iodide as a thyroid blocking agent in incidents involving exposure to radioactive iodine. It is expected that licensees will review this information for applicability to their licensed activities and distribute this notice to responsible radiation safety staff. However, suggestions contained in this information notice do not constitute new NRC requirements, and no written response is required.Description of Circumstances: During a nuclear pharmacy inspection, NRC and the licensee discussed the possibility of maintaining a supply of potassium iodide at each pharmacy location. This supply would be used as a thyroid blocking agent in case of an iodide-131 sodium iodide spill with possible personnel contamination. The licensee asked for a statement of NRC's policy regarding on-site storage of potassium iodide for use in incidents involving radioactive exposures. There is an NRC and Federal Emergency Management Agency (FEMA) policy addressing on-site storage of FDA-approved "radiation emergency potassium iodide" as a thyroid blocking agent for power reactor emergency workers (Federal Register, Vol. 50, No. 142, p. 30258, July 24, 1985).Discussion: There is no NRC policy on non-reactor licensees using FDA-approved "radiation emergency potassium iodide" (i.e., the generic drug nomenclature). However, as discussed below, licensees may wish to provide for its availability in case of an emergency.The FDA has evaluated the medical and radiological risks of administering potassium iodide for thyroid blocking under emergency conditions. The FDA has concluded that FDA-approved "radiation emergency potassium iodide" is safe and effective and has approved it for over-the-counter sale for this purpose (Federal Register, Vol. 50. No. 142, p.30258, July 24, 1985). FDA guidance states that risks of side effects, such as allergic reactions, from the short-term use of relatively low doses of potassium iodide for thyroid blocking in a radiation emergency, are outweighed by the risks of radioiodine induced thyroid nodules or cancer, if the projected dose to the thyroid gland is 25 rems or greater. Because FDA has authorized the non-prescription sale of "radiation emergency potassium iodide," it is legally available to organizations or individuals who, based on their own corporate or personal analysis, choose to have the drug immediately available. At this time, ANBEX, Inc. [PMB 284, 35246 US Hwy. 19 N, Palm Harbor, FL 34684] and Carter-Wallace, Inc. (P.O. Box 1001, Cranbury, NJ 08512) are the only companies that have received FDA new drug application (NDA) approval for their non-prescription "radiation emergency potassium iodide" drugs. These drugs are not stocked in pharmacies and must therefore be ordered directly from the companies. The non-prescription "radiation emergency potassium iodide" is manufactured at the proper adult dosage for thyroid blocking, is readily absorbed by the body, and has a package insert providing information on the dosage, method of action, warnings and storage. The directions in the package insert should be followed. Other forms of potassium iodide are available by prescription only. Potassium iodide is effective as a thyroid blocking agent. It reduces thyroid gland accumulation of radioiodine that has entered the body through inhalation or ingestion if the potassium iodide is administered before, or immediately after, exposure to the radioiodine. If potassium iodide is administered later than four hours after an individual has suffered an acute ingestion or inhalation of radioiodine, its effectiveness as a thyroid blocking agent is less than 50 percent.If the licensee wants to implement a potassium iodide thyroid blocking program, the potassium iodide should be on hand (because it is not readily available), and guidelines should be developed to ensure rapid determination of whether a radioactive iodine spill or leak warrants administration of the potassium iodide. The guidelines should also address the more detailed measurements, surveys, and other follow-up procedures needed to determine whether continued treatment with potassium iodide is needed.It is important to stress that the use of potassium iodide is not a substitute for preventive measures; e.g., proper handling techniques, control measures, and emergency procedures that protect the individual from exposure to radioactive material.Licensees are also advised that although FDA has approved "radiation emergency potassium iodide" for non-prescription sales, licensee or individuals still may wish to consult with a physician about any medical risks of use in an emergency.No specific action or written response is required by this information notice. If you have any questions regarding this matter, please contact the person listed below or the appropriate NRC regional office.

Richard E. Cunningham, Director Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards Technical Contact Donna-Beth Howe, NMSS (301) 492-0636

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