Data about acute exposure is, 34 breast cancers among bomb survivors getting 1-9 rads (rem, cGy) where 42.3 expected and 37 when 10-49 rad (rem, cGy) where 38 expected. Thus I think that 1-10 rad (rem, cGy) is ideal acute,whole body dose. Benefit diminishes thereafter.
Chronic exposure (again second hand) - I would be happy to get 1-10 rem (cGy) /yr extra whole body gamma exposure, and not worry about increased cancer risk unless it was over 50/year, maybe 500. Radon alpha Q and I 131 thyroid shold be factored in where present. I would advise KI be taken only when there has been a clear and heavy release of I 131 because KI will slow metabolism slightly for months (and tastes bad, as in saturated water solution given to liquify sticky mucous and relieve cough).
HPs will be much needed to estimate doses.
Howard Long
Jack_Earley@RL.GOV wrote:
<<If I recall correctly 0.5 REM/year is the guideline for the average
population??? What would you consider a guideline for worrying? Getting all
of that in a week? One day? 10x that in a week? Rough ideas would be
helpful.>>I believe Howard Long (I'm surprised he didn't respond yet but can correct
me if I've misquoted him) has said that hormesis effects diminish after 50
rem acute and 1 rem/day chronic. And I further seem to recall on the
dose-effect hormesis curve that the break-even point for acute exposure is
at 100 rem, which is where some exposed at that level may start feeling
flu-like symptoms. I'm going to have to reach way back into memory here, so
anyone can feel free to jump in with new or more accurate info, but since
the whole-body lethal dose (LD) 50/30 dose is about 450 rem (50 percent of
those exposed without medical treatment will die within 30 days), I guess my
response would have to be, "You don't need to worry at any exposure level."
If you're exposed at that level and don't have access to medical treatment,
it's because none is available anywhere because something equivalent to
nuclear destruction has occurred, whether natural or manmade. Otherwise, at
that level you'll be sick enough to seek medical treatment soon after
exposure, and may be given more radiation to kill additional damaged cells
before a bone marrow transplant. If you're exposed below that level
(recognizing that these are statistical, not absolute, data points), you'll
be sick for a while and then recover. And since a dirty bomb isn't going to
produce those radiation levels (or would incapacitate the bomb-maker/courier
in the process), at what point would worrying come into play? You can be
(rationally) concerned about the conventional explosive, but not the
radiation. It's pretty much in the category of "if it doesn't kill you, it's
good for you." My opinion, of course (for anyone who wants to apply this out
of context).