The Straight’s Radiophobic Hissy Fit

 

This is a guest post from Dr. Rob Tarzwell. Dr. Tarzwell is a nuclear medicine specialist (in training) at UBC in Vancouver, and is on the Faculty of Medicine at the University of British Columbia. He is a CFI advisor.

Vancouver’s Georgia Straight, no stranger to willfully stupid incredulity on science matters, has once again achieved a single-punch self-knockout in its latest piece of gassy hysteria, “Japanʼs Fukushima catastrophe brings big radiation spikes to B.C.

The piece’s author, as deeply misinformed as he is apparently concerned, informs his readership that:

Health Canada detected massive amounts of radioactive material from Fukushima in Canadian air in March and April at monitoring stations across the country.

Lions and tigers and bears, oh my!

Just how massive? Dear reader, I’m glad you asked. Straight journalist Alex Roslin informs us of the actual number, after being sure to wallow in histrionic froth with absolutely no sane context: 3.6 milliBecquerels per cubic metre of air. What does that mean?

One Becquerel is the disintegration of one radioactive nucleus per second. 3.6 *milli* Becquerels represents 0.0036 disintegrations per second, in a cubic metre of air. What does that mean?

Essentially, it means you need to inhale 278 cubic metres of air to internalize enough I-131 to achieve 1 Bq of internal activity (1/0.0036=278), or, 278,000 litres. Also, this means every litre of air contains about 3.6 atoms of I-131.

By comparison, in every litre of air, there are 2.69×10^22 molecules of gas. In long form, that is 26,900,000,000,000,000,000,000. Remember that iodine in gaseous form combines into I-I, so those 3.6 atoms are 1.8 molecules, and the percentage of I-131 is, therefore, 1.8/26,900,000,000,000,000,000,000. Do I really need to do the math for you?

Furthermore, the average human adult only breathes 8 litres of air per minute. It would take about 24 days of breathing at rest to consume enough I-131 (1 million atoms) to guarantee 1 Bq. But I-131 has a half-life of 8 days. So by the time you have inhaled 278,000 litres of I-131, it has decayed three times, and the total radioactivity is then only 0.125 Bq, or 1.25 disintegrations every *ten* seconds.

At a concentration of only 3.6 mBq (1 Bq in 278,000 litres), you literally *cannot* breathe enough air to ingest 1 Bq of I-131.

Even so, should you be worried? Your own body contains potassium-40, a radioactive form of potassium, and you experience approximately 266,000 disintegrations per minute.

So, The Straight is raising alarm bells over 0.0036 nuclear disintegrations per second, completely ignoring the constant internal radioactivity of 4,433 potassium-40 atoms disintegrating each second of your life. Oh! I totally forgot to mention radiation from cosmic rays, and radon gas, and medical x-rays, and bananas, and instant coffee, and dried fruit, and. . .

Step away from the iodine tablets, folks. You’ll be ok.

Photo from Flickr user gsbrown99 under a CC licence.

EDIT: Post updated August 11 to reflect calculation error identified below.

6 Responses to “The Straight’s Radiophobic Hissy Fit”

  1. Thomas Doubts says:

    Way to go guys. This is a conversation I’ve had with so many people since the earthquake that I’m sick of hearing myself talk about it.

    I don’t know specifically about The Straight’s science reporting deficiencies, but as we (the skeptical community) have seen time and time again, reporters are @#$%in’ lazy when it comes to informing themselves about science, and jaded editors are far too willing to sacrifice accurate headlines/ledes in favour of sensational ones that grab more eyes. A sad and depressing fact of life.

    Way to go Dr. Tarzel for setting the record “straight” (ha-ha) in such an easily digestible fashion. Too bad the national news outlets didn’t bother to dig a little. Christ, they don’t even have to dig that far. All they had to do was scratch the surface to learn a little about radiation.

    Aaargh!

  2. Rob Tarzwell says:

    Hi all. I’ve just detected an error in my math which is worth mentioning for accuracy and completeness, but it does not have an important impact on the result.

    The formula for determining the number of atoms in a radioactive sample using the activity level is given as:

    A=NL

    A is the activity in Bq
    N is the number of atoms
    L is the decay constant, the fraction of the sample decaying in a given second. It can be determined from the half-life as ln(2)/(half-life in seconds).

    I-131 has a half life of 8 days, which is 8*24*3600 = 691,200 seconds.

    N=A/L

    N=1 Bq/(0.693/691,200) = 997,400 atoms of I-131 in a sample decaying at one disintegration per second.

    So, you would still need to inhale all 277,000 litres of air to have ingested 1 Bq of I-131, but this would be about 1 million atoms, not 1 atom. After 8 days, you would have inhaled about 8/24.1 = 1/3 of 1 million, or about 333,000 atoms, and if these magically had not decayed, you’d have internal radiation of 1 distintegration every 3 seconds.

    Bottom line? even if you had all 1,000,000 atoms injected into you at once, this would still be 1/4433th of the radiation from internal potassium-40.

    My apologies.

  3. Christopher says:

    Thanks for writing this. The Georgia Straight gets more ridiculous all the time but I couldn’t believe it when I saw the Fukushima scare piece.

  4. Rob Tarzwell says:

    Thanks for publishing the corrected article!

  5. Jeff Finger says:

    Several other stupid errors in this piece, again in the numbers. And its all about the radiation numbers, really.

    Article states that the radiation level from BC stations rose from 0.43 microsieverts/day to 0.48 microsieverts/day, which is 0.02 microsieverts per hour. Note that world average background radiation from all sources is 3 millisieverts, or 0.34 MICROsieverts/hour. My own gieger counter in Vancouver shows 0.12 microsieverts/hour. How can Alex Roslin in all seriousness panic us about an exposure level of 0.02 microsieverts.

    Next Roslin tries to educate us about air exposure limits. He correctly states that the CNSC ceiling is exposure to 200 millibecquerels per metre air every day for a year. He then translates this to being the same limit as 16.7 millibecquerels per meter air for 30.4 days. He has just lowered the limit by 143 times with his fundamental misunderstanding of the unit and dosage.
    Then he scares us with reading of 33.3 millibecquerels for 30.4 “days of elevated radiation”

    Put another way, if 200 every day for a year is still OK, then a temporary spike to 33 for 30 days is insignificant.

    There are other error here as others have pointed out. If the author can’t get the basics right, then I can’t trust anything else he says.

    How do we get the truth PUBLISHED in the Straight on this?

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  • Rob Tarzwell

    Rob is a Vancouver based physician with specialty training in psychiatry and nuclear medicine, and he is a Clinical Instructor on the Faculty of Medicine at UBC. He has publicly debated creationists and anti-WiFi activists, lectured on the importance of flu vaccines, and he writes articles in response to medical misinformation. He is convinced that, one day, one of those windmills he tilts at will actually fall over.