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Nathan Myers

The most frequent use of radiation units in public media is to mislead
people about radiation risks. The universally cited linear extrapolation
of health risks, from high exposures to low, has never been based on
measurements. It's hard to see how it ever could be. What we can say with
confidence is that it's almost certainly not linear.

Worse, full-body exposure is meaningless when radionuclides concentrate in
specific body tissues -- dust in lungs, iodine in the thyroid gland, metals
in bones. Then, your total radiation exposure may be indistinguishable
from nominal background, yet reliably destroy and mutate cells near the
contaminant over a long period. John Wayne was much more probably killed
by the picograms of fallout dust he breathed in and retained than the few
days' irradiation he got on-set downwind of that H-bomb test.

The curie is an interesting unit. It make releases of long half-life
radionuclides seem less harmful than short half-life materials. You may
release overwhelmingly more cesium than iodine, but the same number of
curies each. The level of iodine exposure may be considered small, given
that it will decay to nothing in a few weeks, but the much more abundant
cesium, when an immeasurable bit of it finds its way into your bones, will
continue radiating long after your death.

Examples of such misleading usage are easy to find, such as in the
frequently repeated Three Mile Island statistics. Average gamma radiation
dosage in a radius around TMI extrapolated from a few high-ground samplings
means nothing for the people in the valley basin downstream bathed in heavy
gaseous and suspended radionuclides for days.

As scientists we are congenitally disposed against misleading anybody.
It's all too easy, though, to repeat published numbers and seem to be
saying -- and even to believe ourselves -- what the numbers do not really
say at all.

An interesting discussion of specifics may be found in the postings at
http://www.tinyrevolution.com/mt/archives/2011_03.html , and in the month

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