Re: Anti-radiation articel - Thoughts please!

[Leo Lowe <llowe@senes.on.ca>]

The statistics on fatality rates (deaths per million per year) that you
give for the manufacturing and construction workers seem about right (based
on actual body counts), but it appears that estimates for radiation workers
are based on a lifetime of exposure, not a single year.

As has already been discussed, assuming the validity of the LNT model, and
using the ICRP60 probability coefficient for fatal cancers of 40 x 10(-6)
per mSv [ or 4 x 10(-4) per rem] for occupational exposures, the number of
fatal cancers per year of exposure in 1 million workers each exposed to 20
mSv/y is:

		(40 x 10(-6)) x 20  x (1 x 10(+6)) = 800.

It appears that the quoted figure for radiation workers of 37,500 has
assumed a lifetime (50 y?) of occupational exposure.  There is often
confusion between a lifetime risk from a lifetime of exposure and a
lifetime risk (since radiation risk is protracted) from a year of exposure.

The above equation also assumes that every worker would be exposed at the
limit  (ICRP60 recommended limit of 20 mSv/y).  In fact, experience has
shown that the average dose to workers is a small fraction of the dose
limit, typically 1/10.
Therefore, the expected number of cancer fatalities @ 20 mSv per year would
be in the order of 80, based on the above equation.

Finally, as also has been previously pointed out, the construction and
manufacturing figures appear to be accident rates, not occupational disease
rates.

Leo M. Lowe, Ph.D.
Principal, Senior Health and
Environmental Physicist

SENES Consultants Limited
121 Granton Drive, Unit 12
RICHMOND HILL, Ontario
Canada L4B 3N4
Tel:  (905) 764-9380
Fax:  (905) 764-9386
Email Address:  llowe@senes.on.ca
Web Site:  http://www.senes.on.ca/
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