Harmful radiation from Japan is not reaching the United States—no need for Americans to take potassium iodide

Peter Wehrwein

Contributor, Harvard Health

A conversation with disaster planning expert Dr. Richard Zane

The situation at the Fukushima Daiichi nuclear power plant in Japan is far from being under control. And no one should downplay the triple catastrophe in Japan—a failing nuclear power plant on top of an earthquake and a tsunami that claimed at least 10,000 lives. But U.S. government officials, as well as some outside experts, say there is no reason to expect that harmful radioactive emissions from the crippled reactors will reach the United States. That means there’s no reason to stockpile or take potassium iodide pills.

The Union of Concerned Scientists, a well-regarded organization in Cambridge, Mass., that describes itself as nuclear safety watchdog, explained why this way:

While wind patterns will likely carry the radioactive plume eastward, since Japan is thousands of miles from the United States, radioactive material in the air will be so diffuse by the time it reaches Hawaii, Alaska, or the mainland United States that it is highly unlikely to create significant health concerns.

The U.S. Environmental Protection Agency (EPA) has been posting data from radiation monitors. You can check out graphical representations of that data by clicking hereand then clicking on the pink and blue dots on the map (if you have a slower computer, some of the graphs may be slow in loading). A monitor in Hawaii did detect radioactive atoms (isotopes) last week that might have originated at the Fukushima plant. Even so, all the monitors are showing radiation levels that are fluctuating at normal background levels.

Yet Americans have been buying up potassium iodide to protect themselves against radiation that they fear is coming over from Japan—or to get ready for a nuclear power plant accident here.

I spoke with Dr. Richard Zane about the situation. Dr. Zane is vice chair of the emergency department at Harvard-affiliated Brigham and Women’s Hospital and medical director for emergency preparedness for Partners Healthcare in Boston.

Q: Should people in United States be taking potassium iodide pills?

A: There is zero indication that any Americans should be taking potassium iodide.

Q: Why?

A: Any radiation being emitted from the plant itself is exceedingly unlikely to reach the United States and if it does, it will be so little as to pose no risk. In addition to other factors, radiation decreases as a function of distance.

So the only way anyone in the United States would be exposed would be through radioactive fallout—radioactive particles floating across the Pacific Ocean and then settling on areas in the United States. The fires and explosions at Fukushima plant have released some radioactive material into the air. But it would take a much, much larger catastrophe for radioactive material emitted in Japan to travel 5,000 miles and reach this country in concentrations that would be at all consequential.

Even if weather conditions were just right—meaning no rain, since rain would wash radioactive particles out of the atmosphere—not nearly enough material has been released from Fukushima for it to reach the United States, including Alaska and Hawaii, in amounts that are close to being harmful.

Q: Is there is any danger to take potassium iodide?

A: Potassium iodide can cause gastrointestinal distress and make you feel pretty unwell. And the extra iodine can be a problem for people with thyroid conditions like Graves disease and autoimmune thyroiditis.

Q: Some people are buying up potassium iodide now in case of nuclear accident closer to home. Does that make sense?

A: Not really. Hoarding it could create shortages. Besides, potassium iodide is not an anti-nuclear panacea or a cure. It protects just the thyroid gland, not the rest of the body.

Q: So what is the best way to protect yourself in case of a nuclear emergency?

A: If there were a nuclear emergency near where you live, the best way to protect yourself is probably not going out to get potassium iodide. The best strategy is to get a significant distance from the source of the radiation. That is why we have evacuation plans for areas near nuclear power plants, and it’s the reason Japanese officials have taken the important step of evacuating people from the area around Fukushima nuclear power plant.

If evacuation isn’t feasible or advised, then the next best thing to distance is putting a barrier between yourself and the radiation. As a practical matter, that means staying inside with the windows and doors closed. Walls and closed windows would block some of the radiation. Staying inside also helps prevents contact with radioactive particles.

If you do come into contact with radiation or radioactive particles, you should take off any clothes you are wearing and wash off in a shower as soon as possible.

Personal and family preparedness for any type of disaster is very important. The basics are to organize a kit, make a plan, and be informed. I recommend the government Web site, www.ready.gov

Q: Do you have potassium iodide pills at home?

A: I live in the suburbs outside of Boston about 50 miles from the nearest nuclear power plant in Plymouth, Mass. and no, I do not have any potassium iodide pills at home. It’s exceedingly unlikely that I will need them and there simply is no reason for me to have any. I do however have a kit, a plan and am informed.


  1. Commission Tsunami

    I think that a Commission to study the effects of the tsunami is needed

  2. Alan Williamson

    Very Interesting

  3. Anonymous

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  4. Charles in Hawaii

    You may have eased my fears from radiation in the air, but I heard some disturbing news. You mentioned that the only way we will be affected is by a radioactive fallout. Didn’t they find mutated / disfigured marine life near the Fukushima plant?

    Living in Hawaii and having seafood as a main staple, are there any home detection methods to check for radiation in fish / seafood?

    It’s understandable that stirring up a panic is the last thing officials want to do and, thus, we need to look after ourselves.

    Aloha for your contribution!

    • Charles in Hawaii

      Forgot to ask this on my previous comment. You mentioned creating a barrier between radiation and your body reduces exposure…if walls and window were to remain closed, what degree of air (conditioner) filters are needed?

      Mahalo again,

      [URL removed by moderator]

  5. Tanya

    Isn’t natural background radiation different to ingesting or inhaling the radiation that comes only from nuclear fission such as C-137 or plutonium. From the information on the EPA website it says that these can stay in your body and lodge in one place. From my conclusions not even one molecule of the products of nuclear fission is a safe level as even one molecule can cause mutations particularly in the very young.

    Why are you telling the people of America not to take iodine or switch to iodized table salt, or dab on some iodine solution, when there is precipitation in places hundreds of time the legal dose limit.

  6. jim

    No HARMFULL levels of radiation will reach US. Radiation is everywhere, you get a larger then average dose when you fly in an air plane, or have an x-ray. Granite (in kitchen countertops) gives of more radiation then other building materials. In the 70’s they tried to sell a ‘sodium free’ table salt, substituting potassium chloride for sodium chloride. Potassium has a higher natural occurrence of radioisotopes; potassium chloride salt will set of a geiger counter. We are exposed to radiation all day every day. The levels that will reach US, with the dilution that occurs across the pacific ocean, will not raise our exposure by a significant amount. All elements have a certain amount of naturally occurring radioisotopes (ie. C, N, O, H) so every thing you ever come into contact with gives off radiation, only very high levels become hazardous.

  7. Richard

    No chance of radiation reaching the United States? Perhaps one should look at what was found in the rain water in Massachusetts some 6,700 miles from Japan. This Radiation from Japan has already Radiated the Pacific near the Japanesse shore by over 1,000 times normal. Contaminated sea food from the Pacific may find its way all over the world. “Harmful Radiation From Japan Is Not Reaching The United States” (how do you know its not harmful for exposed humans 5 or 10 years from now? or exposed wildlife for that matter.)

  8. Dave

    What about radiation entering the food chain via seafood?

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