Rational Talk on the Threat of Radiation from the Japanese Nuclear Disaster

Heather says:

I’ve been monitoring reaction to the potential threat of exposure to radiation drifting across the Pacific from Japan to the West Coast of the United States. I had noticed some extreme reactions and thought now would be a good time to ask my good friend Eugene to comment on the situation. Some of you will recognize Eugene as Imabug from the comments. I’ve known Eugene for the past five years and my husband attended his presentation at BarcampCHS back in November of 2010: Talking through Radiation FUD (Fear Uncertainty and Doubt). Tim was a nuke in the Navy on an aircraft carrier, so between the two of them, Home Ec 101 has some serious resources when with comes to understanding radiation. If you have questions, ASK them. Both Eugene and Tim will be happy to answer them without drama or fear mongering.

From Eugene:

Radiation from Japan

Disclaimer: I am not a nuclear reactor engineer. I am a medical physicist specializing in diagnostic imaging. I know about radiation.

Do I need to worry about the radiation?

The amount of radiation that has been released from the damaged reactors in Japan is unknown, but you can be pretty much guaranteed that if any of it does reach the west coast of Canada or the US, it will be at very very low concentrations and detectable only by very sensitive radiation detectors. There is a lot of air and weather between the western US/Canada and Japan that will serve to dilute and wash out any radioactive materials in the atmosphere.

The time it takes for stuff to blow from there to here also means some of the radioactive materials will decay away, further reducing the amount of radiation that reaches here. It’s been over a week since the earthquake and initial explosions at the reactor so any airborne radioactivity would probably have reached the US by now. There have been reports of radioactive contamination detected at various airports around the US, but that is due to the radioactive material coming in on planes and passengers.

Radiation monitoring stations maintained by the EPA have not detected any significant levels of atmospheric radioactive material from the Japanese reactors.

If you’ve been following the reports in the media recently, you’ll have heard people talking about stocking up on radiation or potassium iodide (KI) pills.

Some people will tell you it protects against radiation poisoning (which by the way is a completely inaccurate term), others say it protects against radiation exposure or blocks the effects of radiation.

What potassium iodide will do is saturate your body with stable (non-radioactive) iodine so that the thyroid can’t take up any radioactive iodine that might be present in your body.

That’s all potassium iodide does.

It’s also only effective when it’s taken a few days before the exposure occurs. It’s not going to protect you from the radiation given off while the radioactive iodine wanders the body waiting to be sucked up by the thyroid.

It’s not going to protect you from any other type of radiation.

It just keeps your thyroid from taking up the radioactive iodine because there’s so much more stable iodine in your body.

At this point there is no reason for anybody in the US to start taking KI because of the reactor situation in Japan.

Reliable information sources:



  1. James Moffitt on March 29, 2011 at 10:02 am

    A good friend of mine just sent this to me. I would like to know if there is any validity to this. I did send him your post Eugene just in case he is panicked over nothing.
    My friend states.

    Radioactive Iodine has reached SC from Japan. The government is not telling us the entire truth.
    They are saying it is a very low dose and not a problem. A low dose over 2 or 3 months WILL be a problem.

    Go to youtube.com
    search: 'radiation jetstream forecast'
    This guy is using worldwide weather stations to track radioactive fallout.
    watch the 3/27 update and every update from now on.


    My recent post Saturday at the gym

    • Eugene Mah on April 1, 2011 at 11:19 pm

      It's a very alarmist spin on those *model* projections. Far, far more than it needs to be. While he says that "moderate" levels of radiation are reaching the US, he fails to point out the scale used on the graphs, which are in Bq/m^3 or Becquerel per cubic meter. 1 Becquerel is equivalent to the decay of 1 radioactive atom per second, and is a very tiny amount. From website he was using in most of the video, the "moderate" levels of radiation he was pointing out were in the 1-10 Bq/m^3 range. Hardly what I would call moderate. You'll probably find that much radioactivity in the display of bananas at the grocery store.

      The EPA website has data from all their monitoring stations available. You don't need to be a scientist to see that for any randomly picked station, there's virtually no change in the trend of the graph before and after the Japan quake.

      From some of the other videos of his that I've seen, I'd call him someone who likes to look at pretty pictures but has no real understanding of what they mean or how to properly interpret what he's looking at.
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  2. Eugene Mah on March 24, 2011 at 1:53 pm

    hey, my original comment came back!

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  3. dcrmom on March 23, 2011 at 6:04 pm

    Thanks for this info. Being in the Philly area, I'm not worried about Japan, but I do live within miles of a nuclear power plant and everyone in our area is prescribed iodine tablets in case of the event of a disaster. So you are saying it would be pointless to take them after the fact?
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    • Eugene Mah on March 24, 2011 at 8:16 am

      it's not entirely pointless taken afterwards. KI in pill form will take some time to be absorbed into the body (it's also available in liquid form which offers faster absorption, but it's pretty nasty stuff). In the event of emergency, it will still be effective taken within a few hours before or after the exposure. The longer you wait after the radioactive iodine gets into you, the less effective the KI will be although it will help prevent the thyroid from sucking in even more radioactive iodine once you've been exposed.

      Once the radioactive iodine is inside the body, there's no way to completely prevent the thyroid from taking it up. The thyroid can't tell the difference between radioactive and non-radioactive iodine. It will suck up whatever iodine that it needs. The purpose of KI is to provide more non-radioactive iodine for the thyroid to take up than there is radioactive iodine.
      My recent post Term paper hell

  4. James moffitt on March 22, 2011 at 12:39 pm

    This article was easy to read, informative an educational. Thanks to Heather and Eugene for providing this service.
    My recent post Which way did he go now

  5. HeatherSolos on March 21, 2011 at 4:03 pm

    People tend to hear radiation and freak out. In a way it makes sense, radiation can be scary stuff, we just have to learn to take things in context.

  6. Stacy on March 21, 2011 at 2:17 pm

    Thanks for this post. It's hard to know what's real and what's hype if you're ignorant on this subject. Since we're on the West Coast, I have thought about it, but I really didn't know what was what. Thanks again.

  7. Karen L on March 21, 2011 at 12:56 pm

    I was just about to comment to link to the XKCD radiation graphic but I see you’ve already done that. It’s pretty nice for putting things in perspective. Notice the relative sizes of daily exposure near Fukushima (0. 003 5 mSv daily = 1.28 mSv annually), taking a flight (0.040 mSv per flight) and the _minimum_ annual exposure known to increase the _risk_ of cancer (100 mSV).

  8. Heidi@CarolinaDreamz on March 21, 2011 at 9:34 am

    Thank you Eugene, for shedding important light on this worrisome problem. I have family, in the West, that probably don't even know anything happened in Japan. So I haven't tried to alarm them, but I've been worried. I think it would be nice to know the differences between this type of radiation exposure and the everyday exposures we have.

    My recent post Update from California

    • Eugene Mah on March 22, 2011 at 11:26 am

      The background radiation everybody gets comes from cosmic rays and radioactive materials from the ground such as radon.

      In the case of reactor accidents like in Japan, Chernobyl or Three Mile Island, the radioactive materials of primary concern are iodine (sucked up by the thyroid), cesium and strontium (both behave like calcium).

      Until you start getting into the gory details, there's really not much difference between the two other than the fact that everybody is exposed to background radiation no matter what they do or where they live while radiation from reactor incidents tends to be localized for the most part.
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