Will iodine and potassium iodide protect against radiation from Japan?

People in the United States are rushing out to take iodine pills, specifically in the form of potassium iodide, to combat the threat of radiation spreading from the nuclear events stemming from the Japan earthquake and tsunami.

There are numerous reports that pharmacies in California have run out of the drug.

Potassium iodide works when the thyroid takes it up, instead of the potentially dangerous radioactive iodine that comes from a nuclear fallout. In theory, this can protect thyroid from potential cancer due to radiation exposure.

But, according to numerous experts, the threat of radiation from the crippled Japanese nuclear reactors to the United States is extraordinarily low.

As reported in MedPage Today,

Jonathan E. Fielding, MD, MPH, health officer for Los Angeles County, said he and other public health authorities still believe that Californians faced “minimal risk of radiation exposure” from the Japanese nuclear facility, even though news reports indicated that a series of explosions had breached the containment building surrounding one reactor.

“I want to stress that there is no reason to purchase potassium iodide at this time,” he said. Fielding also urged those who had already bought the pills not to take them, as they can have adverse effects.

Iodine tablets typically work when taken before radiation exposure, or immediately after.  So, in the cases of panicked California residents, it’s unlikely that taking potassium iodide will protect them.

And there are side effects as well, including inflammation of the salivary gland, allergic reactions, and gastrointestinal side effects.

Worse, according to USA Today,

taking the pills too late — a week after exposure — can actually cause radioactive iodine to get locked in the thyroid, Inabnet says. That’s what happened at Chernobyl.

Instead of spending time and money to find and purchase iodine, it’s much more useful to use those dollars and contribute to the Japan earthquake and tsunami relief efforts instead.

 is an internal medicine physician and on the Board of Contributors at USA Today.  He is founder and editor of KevinMD.com, also on FacebookTwitterGoogle+, and LinkedIn.

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  • http://fertilityfile.com IVF-MD

    Sure, Fielding’s statements that the risk is low is based on the current status. Is it fair to conclude that the status is not stable and in a state of flux with many different possible future outcomes as events evolve?

    So while there is no utility for ingesting iodine today, at this hour, is there the possibility that it might be of use, let’s say, four days from now? If so, would four days from now be the optimal time to prepare for acquisition or distribution of iodine?

  • rjh

    A lot depends upon your assumptions regarding event probabilities. RadioIodine has a half-life of 8 days. It is generated by the fission reactions. The reactors are shut down and no longer creating new radioiodine.

    It’s extremely unlikely that fission reactions will resume. The problem is cooling the fuel rods that are still generating lots of heat as the fission products decay. Without cooling these can overheat, melt, etc. That spreads the contents but does not change the isotope mix.

    As time passes, the utility of iodine pills is rapidly dropping. If fuel rods overheat, melt, or otherwise leave containment, the concern will be the longer life isotopes. These are mostly heavy isotopes that take different pathways.

  • http://www.ircalum.com Aluminum Plate Washington

    I’m torn as to which “side” to take as far as whether it’s worthwhile to buy PI pills. I have to agree with the first comment though that this is an evolving situation and as far as I know we aren’t out of the woods yet… even if the probability is really low for problems stateside.

  • dr. jack ga patuto

    i doubt iodide pills will be of value for now…..some thyroids fail to uptake P-iodine……besides ,in america,we are exposed to high amounts of radiation since we make our 1st trip to the dentist and not to mention—all radiological procedures that the average person is subject to in their lifetime…….
    but then—that is my opinion…
    a 20 year flight surgeon vet and former dr. of the world

  • ninguem

    Back in 2006, with the 20th anniversary stories of Chernobyl, some scientists remarked that wildlife is thriving around Chernobyl.

    The studies got some attention recently, with the current mess at that Japan reactors.

    How accurate the stories are (the thriving wildlife, that is), I don’t know.

  • http://www.coleman-pharmacy.com rmurphy

    Two issues: radioactive Iodine release and dispersal.
    IVF has a very valid point, b/c radioactive iodine, very likely, IS still being produced by the fuel rods, besides it leaches from spent fuel rods as well. To boot, fission reactions do not simply “turn off”. Neither has it been suggested that TEPCO has been able to completely stop the reaction. The combination of damaged reactor containers and exposed spent fuel rods does mean that radioactive iodine is being released in all likelihood.

    On distribution and exposure risks. True, I 129 half life is 8 days, but half life means half! 80 days is the time period for risk of I 129 uptake. If you recall, the first nuclear tests in the US were conducted above ground in Nevada and New Mexico. The radioactive iodine was carried on easterly winds and had its highest deposition concentrations in the area centered about the region of the kansas, oklahoma, missouri, and arkansas borders, 1300 miles. If I 129 is released in significant doses it will travel towards the US but unlikely that it will reach the US mainland — or anywhere close! Further, common practice is for people in a 50 mile radius to take an iodine supplement to flood the system and prevent thyroid uptake of radioactive iodine.

    Final recommendation: Do not take an iodine supplement. Avoid fresh-caught pacific fish for a few months.

  • dave

    Extremely low chance? Watch the news………….

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