Effect Measure

The UK’s Health Protection Agency has a follow-up on their monitoring of people and places potentially contaminated with the extremely dangerous alpha-emitter, Polonium-210, the weapon used to kill Russian dissident Alexander Litvinenko (see our posts here and here about Polonium-210, and here and here about the murder). Their spin is that tests “so far” show minimal risk to the general public. What surprised me is that their tests showed widespread exposure to the public. Here are the reported results:

Test result update

Category 1
*596 people had results ‘below reporting level’ – below 30 millibecquerels (mBq) per day (natural levels of Po-210 in urine are typically in the range 5-15 mBq per day). It is therefore unlikely that any of these people had been exposed to Po-210

Category 2
*85 people had results above 30 mBq per day in their urine, but with a dose less than 1mSv indicating no public health risk, and no health concern to the individual, but probable contact with Po-210

Category 3a
*35 people had results above 1 millisievert (mSv), but below 6mSv indicating no public health risk, and no health concern to the individual, but probable contact with Po-210

There are 716 results in categories 1, 2 and 3a and these are NOT [their emphasis] of health concern.

Category 3b

*17 people had results above 6mSv which are not significant enough to cause any illness in the short term and any increased risk in the long term is likely to be very small. (via BigMedicine)

Out of 733 people tested, 137, or almost one in five, showed probable contact with Polonium-210. Of these, 17 or one in eight of the exposed and a bit over 2% of those tested, had levels even Health Protection acknowledges increases their risk, although they characterize that risk as likely very small.

When risks are relatively low in the statistical sense, say in the 1% to 2% range, not low in a public health sense, they become difficult to estimate. Our ability to measure risks at this level is very limited, because it requires good dose information combined with relatively large numbers of people exposed and followed sufficiently long to count the cancers (usually 30 or 40 years). So we have to estimate the risks with the help of data from other circumstances (for example, the atom bomb survivors) and the help of mathematical models that extend the risks found at the high levels to the lower but never measured levels of concern. So we don’t know with confidence how low or high the risks of the Polonium-210 exposed public might be. The judgment the risks are very low is probably correct. Probably. On the other hand, this homicide, using a very tiny amount of an extremely dangerous radioactive poison, exposed 137 other people.

Those are the 137 we know about so far.

Comments

  1. #1 Melanie
    March 17, 2007

    Um, reveres, aren’t you making an argument in favor of the Bioshield idiocy here in the States?

  2. #2 revere
    March 17, 2007

    Melanie: I’m not making any argument. I’m reporting the data.

  3. #3 slovenia
    March 17, 2007

    “What surprised me is that their tests showed widespread exposure to the public.”

    Revere, why are you surprised? Did not the killer(s) contaminate the staff of a popular bar (who presumably contaminated other customers and their friends and families), a hotel room (cleaning staff, their families, etc) and a couple of British Airlines flights? What am I missing?

  4. #4 revere
    March 17, 2007

    slovenia: I had assumed most of the other evidence of radiation was from excreted Po-210 and wasn’t as likely to be absorbed by others. If you slip a ittle in a drink you needn’t have contgaminated so much, but apparently either there was a lot of pre ingestion contamination or the excreted Po-210 was enough to contaminate others. Maybe that shouldn’t have surprised me. But it did.

  5. #5 Greg
    March 17, 2007

    Such sloppiness is not like the Russians.

    One would expect this kind of mess to splash back on the executioner.

    Perhaps the abundant clues rather than the execution were the object.

  6. #6 Melanie
    March 17, 2007

    Greg, say more. You are being too oblique. This story is technical enough for me that I’m going to need my hand held through it.

  7. #7 Afshin
    March 18, 2007

    Why isn’t anyone making the link with another (more) deadly alpha emitter which is being spread by the ton: Depleted Uranium?

  8. #8 revere
    March 18, 2007

    Afshin: Because DU is not a more deadly alpha emitter.

  9. #9 Greg
    March 19, 2007

    Melanie, there are reports, probably true, that the particular mix of polonium isotopes found in Litvinenko comes from a Russian reactor.

    The Russians can make a messy assassination when they want to impress peasants. However, lately, they are noted more for “clean” excutions, like Anna Politkovskaya.. quiet, untraceable, the message delivered without needless pissing off bystanders. Or the dioxin poisoning of Viktor Yushchenko, which is assumed by many to be Russian sabotage, but nobody can outline a plausible script for how it was done.

    Anglos on the other hand, Yanks and Brits, are known for assassinating their enemies and shopworn friends, then screwing up with hamfisted attempts to plant evidence implicating others. Think COINTELPRO.

    Doubtless the Russians found Litvinenko to be irritating. Shot in an elevator with a squeaky clean pistol left beside the body, he would be an unmistakable message. This mess is not like their usual methods.

    Maybe they hired amateurs. Maybe amateurs, or experts, were sloppy.

  10. #10 Steph
    March 19, 2007

    “If you slip a ittle in a drink you needn’t have contgaminated so much, but apparently either there was a lot of pre ingestion contamination or the excreted Po-210 was enough to contaminate others. Maybe that shouldn’t have surprised me. But it did.”

    At least one newspaper report said that a teapot was contaminated, and that the teapot remained in use for several weeks into the investigation. I think the newspaper suggested that the tea pot was missed the first go around and not tested until it had been reused several times.

    This isn’t the news report I read, but it says something similar: http://tinyurl.com/32ggcv