Radiation Exposure and Potassium Iodide (KI)

ACPM has adopted the following policy dealing with the subject:  http://www.acpm.org/2002-059(C).htm.

Here is a summary of the facts about potassium iodide:

• Potassium Iodide (KI), if taken in time and at the appropriate dosage, protects the thyroid gland in a nuclear explosion or accident by blocking, or reducing, the accumulation of radioactive iodine in the thyroid. It does not protect other parts of the body against radiation, does not protect against other radioactive elements, and does not protect against "dirty bombs".
  
  
• Experience in Poland has shown KI to be safe, with a severe side effect rate of 1 in 1 million adults, 1 in 10 million children. It is contraindicated in people with hyperthyroidism and iodine hypersensitivity.
  

• KI is approved by the FDA for over-the-counter sale to the public, and is sold by vendors over the Internet. It is easy to manufacture and to store, and has a long shelf life. It costs $0.25 per adult dose.
  
  
• Prophylactic use of KI in a nuclear emergency as an adjunct to evacuation and sheltering, under the direction of authorities, is recommended by the WHO and different agencies of the US Government. It is provided free to states that have populations near nuclear reactors.
  
  
• Thyroid cancer in children has been the observed major long-term effect of radiation exposure from the 1986 nuclear accident in Chernobyl. Adults are less susceptible to thyroid injury from radioactive iodine. Infants are especially vulnerable.
  
  
• Iodized salt is not a substitute for KI in a nuclear emergency. It cannot be taken in large enough quantity to provide protection before causing harm.
  
  
• During the Three Mile Island accident in 1979, the nation's closest brush with nuclear disaster, the government wound up scrambling to round up supplies of the drug at the last minute.
  
  

Here are some of the arguments advanced in favor of a wide distribution of KI in advance of a nuclear incident:

• The thyroid is the most vulnerable part of the body with respect to radioactive fallout. There is unequivocal scientific evidence that KI works as a blocking agent for uptake of I-131 into the thyroid and can prevent thyroid disease and cancer. Protecting just this one organ is worth the effort.
  
  
• Having KI is better than not.  While the first lines of defense against radiation injury are evacuation, sheltering and avoidance of contaminated food, these actions may not be feasible. If evacuation plans went awry, having KI would be better than nothing. The current thinking in law enforcement circles is that evacuation of a large city is practically impossible.
  
  
• The dosage of KI is not critical. One can take several times the recommended dose without harm.
  
  
• The rate of severe side effects from KI is minimal.
  
  
• Even when taken hours after exposure, KI can still impart some beneficial protection.
  
  
• Problems of distribution to the population in an emergency can be circumvented by predistribution to every household, such as was done in Tennessee, although public compliance was low in that more peaceful period.
  

Here are some of the arguments advanced against wide pre-distribution of KI:

• KI is impractical in an emergency situation, for lack of an effective means of distributing the drug in a timely manner. For optimum effect, it has to be taken within 4 hours of exposure.
  
  
• KI has limited effectiveness in an emergency situation: it protects only one body organ against one isotope--radioiodine. It affords no protection against the other potentially dangerous isotopes that will be released in a reactor core damage accident.
  
  
• KI could be harmful by providing a false sense of security: if it discourages people from evacuating, so as to avoid unnecessary whole body exposure, its availability may do more harm than good.
  
  
• Most people are not going to think about looking for their KI tablets during a nuclear emergency or will have difficulty finding then when they need them.
  
  
• The risk of failure of a nuclear reactor is minimal. The target is very small and difficult to penetrate from the air. US nuclear reactors have a better containment system with thicker concrete shells than the Chernobyl plant.
  
  
• Some in the radiation protection field question the results of the Chernobyl studies and sole reliance on them for policy making, although this stance is refuted by many public health experts. 

Here are links to web sites that contain more information on the subject:

• World Health Organization (WHO)
  The WHO has published a well-researched document setting forth its
  Guidelines for Iodine Prophylaxis following Nuclear Accidents,
  which recommends a KI dosage of 130 mg for adults, lactating mothers and adolescents, 65 mg for children 3-12 years, 32 mg for infants 1 month to 3 years and 12.5 mg for neonates. While the generic intervention level is 100 mGY, it would ideally be 10 mGY for children.
  

• Nuclear Regulatory Commission (NRC)
  The NRC has published a
  FAQ sheet and an Information sheet
  The NRC requires that states with a population within the 10-mile emergency planning zone of commercial nuclear power plants consider including potassium iodide as a protective measure for the general public to supplement sheltering and evacuation. It is providing funding. As of July 10, 2002, sixteen states; Massachusetts, Connecticut, Maryland, Vermont, Delaware, Florida, Alabama, Arizona, New York, New Jersey, North Carolina, Pennsylvania, California, Ohio, Virginia, and New Hampshire have requested and/or received potassium iodide tablets.
  

• Centers for Disease Control and Prevention (CDC)
  The CDC has published an Information sheet
  The CDC states that if radioactive iodine is present, then taking KI will help protect a person's thyroid gland from the radioactive iodine. Taking KI will not protect people from other radioactive substances that may be present along with the radioactive iodine.
  

• Food and Drug Administration (FDA)
  The FDA has published 
  Guidance for the public and 
  Guidance for industry.
  "FDA maintains that KI is a safe and effective means by which to prevent radioiodine uptake by the thyroid gland, under certain specified conditions of use, and thereby obviate the risk of thyroid cancer in the event of a radiation emergency... FDA also emphasizes that emergency response plans and any systems for ensuring availability of KI to the public should recognize the critical importance of KI administration in advance of exposure to radioiodine." The FDA has cleared KI for sale over the counter to the public.
  

• Federal Emergency Management Agency
  FEMA has published its
  Recommendations
  in the Federal Register: "In making a decision whether to stockpile KI, States should be aware that the Federal government believes that the use of KI is a reasonable and prudent measure as a supplemental protective action for the public."
  

• Washington Post
  The Washington Post has published an article that presents a good overview of the subject:
  U.S. Lacks Stockpile of Special Drug
  Anti-Radiation Doses Goal Unmet Since '79
  This article makes the argument that stockpiling of KI is overdue.
  

• Predistribution of potassium iodide--the Tennessee experience.
  Fowinkle EW, Sell SH, Wolle RH.
  Public Health Rep 1983 Mar-Apr;98(2):123-6
  This article describes the distribution of KI to a statewide population.
  

• Potassium iodide for thyroid blockade in a reactor accident: administrative policies that govern its use.
  Becker DV, Zanzonico P.
  Thyroid 1997 Apr;7(2):193-7
  An article reviewing arguments for and against KI use, nuclear reactor design and procedures.