Potassium Iodide: Frequently asked questions
What is it? Potassium Iodide (often known by its chemical symbol, KI) is the ingredient added to your table salt to make it iodized salt; it is approximately 76.5% iodine. “In 1978, the U.S. Food and Drug Administration found KI “safe and effective” for use in radiological emergencies and approved its over-the-counter sale.” Taken orally even in very small quantities 1/2 hour to 1 day before radioactive iodines are swallowed or inhaled, KI prevents about 99% of the damage to the thyroid gland that otherwise would result.
Who stockpiles it? Potassium Iodide and/or Potassium Iodate (KIO3) are now being stockpiled for future nuclear emergencies in Alabama, Arizona, Maine, Tennessee, and Canada, Japan, United Kingdom and South Africa (KIO3), Poland, Armenia, Switzerland, France, Ireland, Czech Republic and the former Soviet Union, among other countries.
What’s the problem? Health experts now estimate that the greatest health concerns affecting the largest number of people from a nuclear accident, or nuclear bomb explosion(s) anywhere in the world, will likely be from the release of radioiodine that is then carried downwind. For example, in certain parts of Belarus, 36.4 per cent of children who were under the age of four at the time of the Chernobyl accident can expect to develop thyroid cancer. “This increase in incidence has been documented up to 500 km from the accident site.”
Very small amounts of inhaled or ingested radioiodine can do grave damage as it will always concentrate, and be retained, in the small space of the thyroid gland, and eventually giving such a large radiation dose to thyroid cells there that abnormalities are likely to result, such as loss of thyroid function, nodules in the thyroid, or thyroid cancer. (Each year 12,000 Americans discover they have thyroid cancer and about 1000 die from it.)
How’s it work? Taking either Potassium Iodide (KI) or Potassium Iodate (KIO3) before exposure will saturate (fill up) a persons thyroid gland with safe stable iodine to where there is no room for later uptake of radioactive iodine.
What does the government recommend? “Potassium iodide, if taken in time, blocks the thyroid gland’s uptake of radioactive iodine and thus could help prevent thyroid cancers and other diseases that might otherwise be caused by exposure to airborne radioactive iodine that could be dispersed in a nuclear accident.” – The Nuclear Regulatory Commission, 1998 ”
A major protective action to be considered after a serious accident at a nuclear power facility involving the release of radioiodine is the use of stable iodide as a thyroid blocking agent to prevent thyroid uptake of radioiodines.” – National Council on Radiation Protection, 1979
“Stable iodine administered before, or promptly after, intake of radioactive iodine can block or reduce the accumulation of radioactive iodine in the thyroid.” – World Health Organization, 1999
How useful is it? There is no magic pill or medicine that will protect you from all radiation sources: “There is no medicine that will effectively prevent nuclear radiations from damaging the human body cells that they strike.” There are numerous other, and very dangerous, radioactive noble gases and/or radioactive fallouts that can be associated with nuclear emergencies. You are still exposed to inhale, ingest, or be radiated externally from any number of dangerous non-radioiodine sources.
Following the Chernobyl nuclear disaster, Poland, received serious radioactive contamination, but authorities blocked the uptake of radioactive iodine in 10 million children by administering potassium iodide (KI) – most received just one dose. Unlike Belarus and the Ukraine, there is no thyroid cancer epidemic in Poland today.
When should KI be taken? The FDA potassium iodide product insert says: “Potassium iodide should be taken as soon as possible after public health officials tell you. You should take one dose every 24 hours.” The Health Physics Journal, Volume 78 No. 6, June 2000, states: “KI administered up to 48 h before 131-I exposure can almost completely block thyroid uptake and therefore greatly reduce the thyroid absorbed dose. However, KI administration 96 h or more before 131-I exposure has no significant protective effect.”
How long is the shelf life? The Long Term Stability of Stocked Potassium Iodide: Jerome A. Halperin, Executive Vice President-CEO of The United States Pharmacopeial Convention, Inc., wrote to the Chairman of the NRC in 1998 of a recent assay of ‘expired’ Potassium Iodide (KI) tablets. “The Thyro-Block Tablets, after the USP Drug Research and Testing Laboratory analyzed samples, showed that approximately 11 years after their manufacture and eight years after their expiry date, the tablets assayed at 99.1% of the labeled content of potassium iodide.” The FDA has issued guidance for extending the shelf life of KI.
Are there alternatives to KI? Potassium Iodate (KIO3), offered in an 85 mg tablet (200 tablets to a bottle), is the ‘cousin‘ of Potassium Iodide (KI). With its extra molecule of oxygen, making it KIO3, its U.S. manufacturer, Medical Corps, claims it has extended shelf life, no bitter taste, and is cheaper per dose. KIO3 has an iodine content of 60%, so two 85 mg tablets (170 mg total, one adult dose) works out to 103 mg of available iodine. The recently updated 1999 World Health Organization: Guidelines for Iodine Prophylaxis following Nuclear Accidents shows both Potassium Iodide (KI) and KIO3 as equals in regards to their bioavailability of stable iodine.
What’s the KIO3 Dosage? Labeled dosing recommendations for the new Medical Corps KIO3, 200 tablets per bottle (85 mg tablets), closely mirrors the above guidelines and are as follows: Adults, and Children over 12 years of age:
Take: 2 tablets per day for 15 days (minimum) to 85 days
Children 3 years to 12 years:
Take: 1 tablet per day for 15 days (minimum) to 85 days
Babies 1 month to 3 years Take:
1/2 tablet per day for 15 days (minimum) to 85 days
Newborns to 1 month: Take:
1/4 tablet per day for 15 days (minimum) to 85 days
Are adverse reactions possible? A 1982 FDA ‘Final Report on KI’ states, “Based on the FDA adverse reaction reports and an estimated 48 x 106 [48 million] 300-mg doses of potassium iodide administered each year [in the United States], the NCRP [National Council on Radiation Protection and Measurements] estimated an adverse reaction rate of from 1 in a million to 1 in 10 million doses.” (Note that this extremely low adverse reaction rate is for doses over twice as large as the 130-mg prophylactic dose.)
WARNING (From FDA): POTASSIUM IODIDE SHOULD NOT BE USED BY PEOPLE ALLERGIC TO IODIDE. Keep out of the reach of children. In case of overdose or allergic reaction, contact a physician or public health authority.
What’s our government’s policy? The US Food and Drug Administration (FDA) updated their 1978 guidelines in 1999. Again, they found KI safe, effective and recommended stockpiling. The US Nuclear Regulatory Commission (NRC) revised their KI rule in December 2000, and now requires states to reconsider their KI policy and will reimburse states that choose to stockpile. The NRC has instructed its staff to work with the Federal Emergency Management Agency (FEMA) to find the most efficient and cost effective ways to help interested states and local governments incorporate the stockpiling of potassium iodide into their emergency plans. The Massachusetts Department of Public Health (MDPH) has supported stockpiling KI only for emergency workers and institutionalized population – such as prisoners – not for the general public. However, in December, 2002, Acting Governor Jane Swift signed into a law (Chapter 425) a bill requiring the MDPH to provide KI to cities and towns on Cape Ann and the Cape and Islands whose governing bodies request it.