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Report to the Radiological Emergency Preparedness Advisory Committee from the Potassium Iodide Working Group

In 1998, the U.S. Nuclear Regulatory Commission (NRC) asked the States to consider, once again, providing potassium iodide (KI) to the general public in the event of a nuclear power plant accident. The REPAC created a KI Working Group consisting of members representing the Bureau of Radiation Protection, the Pennsylvania Department of Health, the Pennsylvania Public Health Association, various representatives from county emergency management agencies and representatives from the medical and health physics (radiation safety) communities. The Working Group met on nine separate days (including one meeting to receive input from interested "stakeholders") from November 1998 through July 2000 to consider this issue. In the interim, there were numerous meetings of assigned subgroups for the specific purpose of considering the science, the logistics of distribution of KI and the best way to interact with and receive input from the public on this issue. Thirty states affected by nuclear power plants have plans to provide KI for their emergency workers only. New Hampshire, one of the thirty states, recently took steps to assure availability of KI to those members of the general public who wish to purchase it from the manufacturers. Three states have developed plans regarding the use of KI for the general public, in addition to their emergency workers. Tennessee distributes KI to the general public within the Emergency Planning Zone (EPZ). Alabama and Arizona stockpile KI for the general public but do not plan to issue the KI unless there is a requiring incident. The Working Group considered the policies of Tennessee, Alabama, Arizona and New Hampshire in its evaluation.

The overriding conclusion of the Working Group was that evacuation is the best policy for protecting the public following the declaration of a General Emergency at a nuclear power plant. Evacuation not only protects the public from exposure to the radioiodines, but it protects from all the other radionuclides that could possibly be released during a nuclear emergency. The Working Group recognizes that there could be at least a finite possibility that, for a variety of reasons, evacuation in a timely fashion might not be possible. In both the Three Mile Island and the Chernobyl nuclear power plant accidents, KI was seriously considered as a protective measure for the general public. In the case of the Chernobyl accident, KI was actually issued to large numbers of people. The effectiveness of KI at Chernobyl in preventing thyroid cancer is a subject of debate in the scientific community. In the event of a severe nuclear power plant accident, KI will most likely again be considered by decision makers as a protective action for the general public. To that end, the Working Group believes there might be value in stockpiling KI. This recognizes the value of allaying public fear and instilling public confidence in governmental actions relative to any potential nuclear accidents. The Working Group evaluated scientific, logistical and public information considerations in formulating the following conclusions:

1. Evacuation is the protective action of choice.
2. The current policy of providing KI to Emergency Workers and Special Groups should be retained.
3. Where indicated (and upon appropriate medical consultation), KI should be used to effectively block the thyroid gland from uptake of radioactive iodine in children and pregnant women*.
4. The Commonwealth should identify sources of KI that would be available for those who wish to acquire it.
5. The Commonwealth should consider stockpiling KI for use in a nuclear emergency.
6. The Commonwealth should develop plans that would permit rapid movement of any stockpiled KI in the event of an emergency that might call for its use.
7. The Commonwealth should provide the public and health care providers with information on the indications for and proper use of KI in response to nuclear emergencies.
8. The Commonwealth should encourage members of the public who are considering obtaining KI to consult, in advance, with their health care providers to see if KI is safe for them to use.

*Specific reference is made to the Considerations, Caveats and Conclusions Section (Section VIII) of this Report.

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Report to the Radiological Emergency Preparedness Advisory Committee (REPAC) From the Potassium Iodide (KI) Working Group

1. Introduction
2. Current Policy
3. Charge of the KI Working Group
4. Meetings and Considerations
5. Subgroup Meetings
6. General Views of the Working Group
7. Logistical Considerations for the Distribution of KI
8. Considerations, Caveats and Conclusions
9. Recommendations of the KI Working Group

Return to Table of ContentsI. Introduction

In 1998, the U.S. Nuclear Regulatory Commission (NRC) asked the States to consider, once again, providing potassium iodide (KI) to the general public in the event of a nuclear power plant accident.

In Pennsylvania, the Pennsylvania Emergency Management Council (PEMC) has primary responsibility for state emergency operations. The operating arm of PEMC is the Pennsylvania Emergency Management Agency (PEMA). PEMC created the Radiological Emergency Preparedness Advisory Committee (REPAC) to provide advice to PEMA on nuclear power plant matters. The REPAC created a KI Working Group consisting of members representing the Bureau of Radiation Protection, the Pennsylvania Department of Health, the Pennsylvania Public Health Association, various representatives from county emergency management agencies and representatives from the medical and health physics (radiation safety) communities. A list of members is found in Appendix A.

Return to Table of ContentsII. Current Policy

The current Pennsylvania policy is to provide KI to emergency workers and special populations that cannot be evacuated in a timely fashion. In the event of a nuclear incident that could potentially release radioactive materials to the environment, evacuation of the public is the primary protective action that would be chosen. KI is not provided to the general public.

Return to Table of ContentsIII. Charge to the KI Working Group

To provide a recommendation regarding the use of Potassium Iodide (KI) in the Commonwealth of Pennsylvania in relation to potential nuclear power plant incidents as a result of the Nuclear Regulatory Commission's (NRC) request for states to review their policy concerning the use of KI.

Return to Table of ContentsIV. Meetings and Considerations

The KI Working Group met on the following dates:

• November 24, 1998:   Initial meeting of the Working Group. Various individuals made introductory remarks to acquaint members with their mission and to explain the inter-workings and authorities of the various agencies as they pertain to this issue. Three subgroups were designated to meet separately, review specific aspects of the issue and report back to the Working Group. These subgroups were SCIENCE, LOGISTICS AND IMPLEMENTATION OF STOCKPILING, and INTERACTIONS WITH THE PUBLIC. It was decided that although the NRC was not through with its deliberations on this issue, the Working group would move ahead with consideration of the issue.
  
  
• February 10, 1999:   The Working Group met, reviewed the results of KI CORE GROUP (Federal) meetings; reviewed the Hanford Thyroid Disease Study¹; reviewed the preliminary report from the Science Subgroup; outlined considerations for the Logistics and Public Interaction Subgroups.
  
  
• May 25, 1999:   The Working Group met, reviewed the results of the KI CORE GROUP meetings; reviewed the results of the Science Subgroup's meetings and preliminary report; developed a tentative schedule for completing the work of the Working Group; heard input from guests and answered their questions.
  
  
• July 13, 1999:   The Working Group met, reviewed activities of the KI CORE GROUP; approved replacement of two members of the Working Group; reviewed the report from the Public Interaction Subgroup; reviewed the report from the Logistics Subgroup; reviewed final report from the Science Subgroup. It was decided that a "stakeholders" meeting would be held in October 1999 to receive input from interested groups or individuals.
  
  
• October 13, 1999:   The Working Group held a "stakeholders" meeting to receive input from interested groups and individuals. This input would be used and considered in developing the Draft recommendations of the Working Group. Presentations were made by Robert Kahler (on behalf of the nuclear utilities in Pennsylvania), Scott Portzline (on behalf of TMI Alert) and Peter Crane, representing himself. There followed a productive interchange between Working Group members and the Stakeholders present.
  
  
• November 15, 1999:   The Working Group met to discuss and come to a consensus on the recommendations of the Group. This was accomplished. A plan for the drafting, reviewing and revising the recommendations was developed and approved.
  
  
• January 6, 2000:   The Working Group met to review, edit and finalize its Draft Recommendations.
  
  
• March 29, 2000:   The Working Group met to review, edit and finalize its recommendations.
  
  
• July 12, 2000:   The Working Group met to review the final recommendations and determine the next logical step in the process.

Following announcement in the PA Bulletin, the Working Group held three public meetings to solicit input from the public prior to finalizing the Report. The meetings were held as follows:

• March 6, 2001:   Community College of Beaver County
• March 20, 2001:   Lancaster County Farm & Home Center
• March 27, 2001:   Schuylkill County Court House

• May 31, 2001:   The Working Group met to consider public input to the Report and to finalize the Report.

Return to Table of ContentsV. Subgroup Meetings

The Science, Logistics and Public Interaction Subgroups held separate meetings during this same period of time to deliberate on their assignments and report back to the Working Group with their recommendations.

Return to Table of ContentsVI. General Views of the Working Group

Thyroid Protection Using Potassium Iodide:

The thyroid gland requires the element iodine for hormone production. The normal American diet amply supplies this nutrient. Some of the materials that can escape to the atmosphere during a reactor accident are radioactive forms of iodine. A fraction of the radioiodines taken into the body accumulates in the thyroid and proceeds to irradiate the gland.

If the thyroid is saturated with stable (non-radioactive) iodine in the form of potassium iodide (KI) before radioiodines are taken into the body, the radioiodines fail to deposit in the gland, and 90% of the radiation dose from the radioiodines is avoided, i.e. the gland is said to be "blocked." To achieve the maximum blocking effect, however, the gland must be saturated with KI before the inhalation or ingestion of the radioiodine occurs. The delay of just a few hours reduces the effectiveness to 50% or less.

KI has long been recognized as a protective agent or prophylaxis against thyroid dose from internal radioiodine uptake. The U. S. Food and Drug Administration approved KI for this specific application in 1982 (47 FR 28158, 6/29/82). KI is considered to be an over-the-counter drug requiring no prescription. In Pennsylvania, the drug is issued for use by Emergency Workers including farmers, and by Special Groups. The recommended adult dose of KI for this purpose is 130 mg. FDA recommends one-half that dosage or 65mg for infants less than one year of age. 130 mg is the commonly available adult unit dose size and supplies of KI come with package inserts.

It should be well understood that KI provides protection only to the thyroid gland and only against radioiodines in the body. It does not protect the thyroid or any other part of the body from other radionuclides that could be released during a nuclear accident, nor does it protect against external exposure from other radionuclides in the plume or deposited on the ground.

The National Council on Radiation Protection and Measurements² (NCRP Report No. 55) concludes that the risk of adverse effects from the use of KI is extremely small, on the order of 5 in 10 million, based on reports of adverse effects from prescribed use. On the other hand, the experience in comparatively uncontrolled conditions is likely to be worse than the NCRP conclusion. The experience in Poland following the accident at Chernobyl suggests a small risk of adverse effects with no fatalities (NUREG/SR-1633)³. This would suggest that over-the-counter use should not result in numerous adverse reactions.

Existing Protective Action Options in Pennsylvania

General Public:  In Pennsylvania the existing protective action options against plume exposure on behalf of the general public include evacuation and sheltering in place. The objective of a protective action is the avoidance of exposure. Timely evacuation is the option of choice because it allows the avoidance of almost the entire dose from the plume and from deposition. The licensee (nuclear power plant owner) is required to make a Protective Action Recommendation (PAR) shortly after the declaration of a General Emergency. Regardless of the limits of that licensee PAR (directional sectors, radial distances, sheltering) state policy calls for the evacuation or sheltering of the entire 10-mile plume Emergency Planning Zone (EPZ) all around. The protective action is implemented in turn by county and local emergency management agencies. This protective action on behalf of the general public does not depend on the existence of an actual plume. It is based on actual or projected plant conditions regarding fuel damage and the efficacy of barriers against atmospheric release. PARs may also be based on dose projections. A dose projection is a calculated radiation dose that will be delivered to individuals in an offsite area if no protective action is taken to avoid the dose.

The protective action of choice in the United States is evacuation, since the general public has almost universal access to private automobiles. This is especially true in rural and suburban areas where nuclear power plants are located. Evacuations because of natural and technological emergencies are fairly common occurrences in the United States. The effectiveness of this protective action is well understood by emergency management agencies.

In the event of conditions that preclude evacuation, e.g. severe weather, competing emergencies, and so forth, the protective action reverts to shelter in place. Shelter affords some protection in terms of shielding from radiation exposure from radioactive materials in passing clouds and some protection against inhalation of nuclides that deposit in body organs such as the radioiodines.

Protective Action Recommendations for evacuation or for shelter are made at a projected dose equal to or exceeding 10 mSv (1 rem) to the whole body or 50 mSv (5 rem) to the thyroid gland of a one-year old child. At a projected dose equal to or exceeding 50 mSv (5 rem) to the whole body or 250 mSv (25 rem) to the thyroid of a one-year old child, evacuation is the only PAR option, regardless of special conditions.

Emergency Workers and Special Groups:  Emergency Workers because of their role in implementing protective actions on behalf of the general public cannot leave the plume EPZ as quickly as the public can in order to avoid the dose. In Pennsylvania, farmers and some industrial workers in the EPZ are classified as Emergency Workers since they need to return to their farms to attend to their livestock or handle crucial functions at the industrial plant. Similarly, Special Groups such as patients in hospitals, residents in nursing homes and inmates in correctional institutions cannot be evacuated in the same time frame as can the general population. These workers and groups are currently provided with potassium iodide (KI) to be taken for thyroid protection if the projected dose to the adult thyroid is 250 mSv (25 rem) or more.

Ingestion of Contaminated Milk, Water and Food:  In Pennsylvania, contaminated commodities and water exceeding their respective protective action guides are embargoed for protection of the public. This is in contrast with conditions in the Ukraine and other parts of Eastern Europe following the accident at Chernobyl where the consumption of contaminated commodities by children was the probable source of most of the thyroid cancers later found there.

Return to Table of ContentsVII. Logistical Considerations for the Distribution of KI

Responsibility for a KI Program

Distribution of KI to the public would be a public health issue and administration of such a program should be focused at the state level.

The KI Working Group discussed and considered four general strategies for making KI available to the general public.

Strategy 1: Make KI available to individuals who desire it. This strategy provides for an ongoing program, under non-emergency conditions, for individuals who desire it to obtain a supply of KI. Several possible ways to implement this strategy are:

• Have KI available for purchase at locations such as local pharmacies, physicians' offices, and public health centers.
• Provide a coupon through advertisements in newspapers, displays in public places, etc. that members of the public could send to a central address to purchase a supply of KI.
• Provide a web site for individuals to purchase KI on-line or to print out a form to purchase it from a central address.

Strategy 2: Stockpile KI locally. The stockpiles would be available for distribution to the public during emergency situations calling for the use of KI. This would require implementation through local government units, local health organizations, nuclear utilities and local private organizations.

Strategy 3: Provide one (or several) state stockpiles of KI at easily accessible locations geographically situated in areas where nuclear power plants are sited. The state stockpile(s) should contain enough KI to supply 500,000 persons, which is about double the population within any 10-mile EPZ. Distribution beyond 10-miles should be based on need and risk as determined by public health authorities.

Strategy 4: Alternative to Stockpiling. The Working Group considered an alternative to stockpiling. The alternative would be for PEMA to pinpoint supplies of KI and to make plans to obtain them on short notice. This would involve locating and assuring commercial supplies of KI, KI already stockpiled and supplies located at hospitals and regional pharmaceutical supply houses.

Packaging and Considerations

The following items are offered for consideration regarding packaging and standardization of KI for the public:

• Packaging of KI in "blister packs" would provide for ease of distribution and security against tampering.
• A two-week supply of KI should be available for each person.
• Provide for uniform expiration dates to simplify replacement of stockpiled KI, if possible.
• Use color-coded packaging with different colors for different expiration dates of stockpiled KI.
• KI should come with a package insert.

Return to Table of ContentsVIII. Considerations, Caveats and Conclusions

1. Fetus: The scientific literature offers little in the way of fetal risk estimates from maternal intake of radioiodine due to the reluctance in administering radioisotopes to pregnant women. Fetal thyroid function begins early in the second trimester. From that time through term, the fetal thyroid is at least as active as that of the infant.
   
   Conclusion:  Thyroid prophylaxis is probably appropriate for the fetuses of pregnant women beyond the first trimester, but only upon recommendation of her obstetrician.
   
   
2. Children: The scientific literature leaves no reasonable doubt that thyroid cancer can be induced in individuals whose thyroids were exposed to external radiation while being treated in childhood for various diseases. The risk appears to occur at doses up to about 1500 rad. Above this dose, the cancer risk falls off due to ablation of the gland.
   
   
   • For purposes of the application of KI prophylaxis, "child" means those individuals equal to or less than 18 years of age.
     
     
   • Following the accident at Chernobyl in the Ukraine, thyroid cancer was observed in individuals who, as children, ingested radioiodine-contaminated commodities produced in the region (NUREG/SR-1633)³. This occurrence may be rooted in underlying dietary deficiencies leading to hypothyroidism and subsequent abnormal uptake of radioiodines and/or to changes in the level of clinical interest in the disease.
     
     
   • For purposes of this report, the risk for thyroid cancer from exposure to internal radioiodines in childhood is assumed to be the same as that from exposure from external sources.
   
   Conclusion:  Thyroid prophylaxis (KI) is probably appropriate for children upon consultation with the child’s health care provider.
   
   
3. Adults:
   1. Irradiation of the thyroid in adulthood, whether from external radiation or from thyroidal I-131, does not seem to be effective in the induction of thyroid cancer.
      
      
   2. The benefit of using KI for thyroid prophylaxis to avoid thyroid cancer in adults has not been clearly established. However, the use of KI by adults may avoid deterministic effects (such as hypothyroidism resulting from thyroid ablation) from very high thyroid radiation doses.
      
      The risk of serious adverse effects from the administration of KI is higher in adults of 45 years of age or older, due to the frequency of diagnosed and sub-clinical thyroid disease (NUREG/CR-6310, Appendix B)⁴, and the use of certain prescription pharmaceuticals that would lead to drug interaction effects.
      
      
   Conclusion:  Thyroid prophylaxis (KI) is probably appropriate for children, but may not be appropriate for some adult populations. Adults who choose to use KI should consult with their health care provider.
   
   
4. Administration of KI
   1. For maximum effectiveness the administration of KI must occur at or before the arrival of the plume containing radioiodines. (Special conditions such as severe weather or competing emergencies that preclude evacuation of the general public will likely preclude timely distribution of KI to the general public from stockpiled supplies.)
      
      Conclusion:  If KI is to be used as a protective action option for children, it must be stored at the point of use, probably the home. The occurrence of special conditions, i.e. severe weather, which could preclude evacuation could also preclude school being in session.
      
      
   2. In the event that evacuation cannot be carried out due to special conditions and shelter becomes the PAR, advisories to administer KI to children and to pregnant women should be included in public announcements.
      
      
   3. Whereas radiation exposure to the thyroid gland of adults does not appear to lead to cancer, such exposure has been shown to cause other deterministic effects (such as hypothyroidism) resulting from ablation. For this reason, providing KI to Emergency Workers and Special Groups is a prudent practice that should be retained.
      
      
   4. KI administration should be continued for the duration of the release and for several days thereafter.
      
      Conclusion:  In the event that KI is part of the protective action language, the protective action should be repeated daily for protection against ongoing airborne radioiodine exposure and against circulating radioiodine.
      
      
   5. The geographic area over which KI prophylaxis could be made available is difficult to foresee. Assuming that accident related thyroid dose from plume exposure is inversely related to distance, the first several miles from a nuclear power plant should receive emphasis. On the other hand, areas outside the 10-mile EPZ may not be amenable to evacuation in a timely fashion in the event of a severe accident.
      
      Conclusion:  KI should be made generally available even outside the EPZ on a self-selection basis, that is, the households secure their own supply from sources of consultation such as pharmacists, physicians, or through the Internet.

Return to Table of ContentsIX. Recommendations of the KI Working Group

1. Evacuation is the protective action of choice.
2. The current policy of providing KI to Emergency Workers and Special Groups should be retained.
3. Where indicated (and upon appropriate medical consultation), KI should be used to effectively block the thyroid gland from uptake of radioactive iodine in children and pregnant women*.
4. The Commonwealth should identify sources of KI that would be available for those who wish to acquire it.
5. The Commonwealth should consider stockpiling KI for use in a nuclear emergency.
6. The Commonwealth should develop plans that would permit rapid movement of any stockpiled KI in the event of an emergency that might call for its use.
7. The Commonwealth should provide the public and health care providers with information on the indications for and proper use of KI in response to nuclear emergencies.
8. The Commonwealth should encourage members of the public who are considering obtaining KI to consult, in advance, with their health care providers to see if KI is safe for them to use.
   
   *Specific reference is made to the Considerations, Caveats and Conclusions Section (Section VIII) of this Report.

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Appendix A. REPAC Potassium Iodide (KI) Working Group

Kenneth L. Miller, C.H.P., C.M.H.P. Professor of Radiology Director, Division of Health Physics M.S. Hershey Medical Center	Chair
William P. Kirk, Ph.D., C.H.P. Chief, Radiation Control Division Bureau of Radiation Protection Pennsylvania Department of Environmental Protection	Vice Chair
Clare A. Carman Deputy Director York County Emergency Management Agency	Member
Randolph Easton Radon Division Bureau of Radiation Protection Pennsylvania Department of Environmental Protection	Member
David Hawk, M.D., M.P.H. Immediate Past-President Pennsylvania Public Health Association	Member
Wesley Hill Hazardous Materials Officer Beaver County	Member
James Jordan, Jr. Deputy Secretary for Health Planning and Assessment Pennsylvania Department of Health	Member Replaced by:
Helen Burns Deputy Secretary for Health Planning and Assessment Pennsylvania Department of Health	Member
Cynthia D. Coventon, M.D. Public Health Physician Pennsylvania Department of Health	Member
Margaret Reilly, C.H.P. Independent Health Physics Counsultant	Member
Joseph A. Romano, M.P.H. District Executive Director, South Central District Pennsylvania Department of Health	Member Replaced by:
Chicquita Morrison Pennsylvania Department of Health	Member Replaced by:
Margaret (Peg) Trimble Director, Emergency Medical Services Pennsylvania Department of Health	Member
Mark Tulchinsky, M.D. Associate Professor of Radiology M.S. Hershey Medical Center	Member
Samuel Tabak Deputy Director Montgomery County Office of Emergency Management	Member Replaced by:
Eric Hoerner Cumberland County Emergency Management Agency	Member
Andrew Simpson Bureau of Plans Pennsylvania Emergency Management Agency	Advisor Replaced by:
Douglas Fleck Pennsylvania Emergency Management Agency

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Endnotes

¹ Hanford Thyroid Disease Study, Tom Hamilton, M.D., Ph.D., Fred Hutchinson Cancer Research Center, Seattle, Washington.

² National Council on Radiation Protection and Measurements, 7910 Woodmont Avenue, Bethesda, MD 20814-3095

³ Draft NUREG-1633, "Assessment of the Use of Potassium Iodide (KI) As a Public Protective Action During Severe Reactor Accidents",( 63 Fed. Reg. 38865, July 20,1998).

⁴ NUREG/CR-6310, "An Analysis of Potassium Iodide (KI) Prophylaxis for the General Public in the Event of a Nuclear Accident", February 1995.

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