hormesis, threshold, LNT theorizing

["A Karam" <paksbi@rit.edu>]

As Ruth pointed out (as have John and many others), there is a lot of inertia among many who support LNT.  However, there is also some well-intentioned reluctance to relax regulations because of the assumption that LNT provides the greatest level of protection to the public.  Those using the "Precautionary Principle" claim that, until we have more concrete knowledge, we should operate under the worst-case assumptions so that we will not put people at risk if, for example, LNT is really true.  However, there are some problems with the precautionary principle.



As one example, we have already got the "low-hanging fruit" in radiation safety.  To reduce dose further costs much more, and this may not be a good investment in overall risk reduction to society.  If the money spent to reduce radiation dose comes at the expense of school breakfast and lunch programs, childhood immunizations, AIDS research funding, highway improvement, etc, then there is likely a net detriment to society, even using LNT to calculate risks, because further dose reduction is so expensive.  So applying the Precautionary Principle in only one area while turning a blind eye to the more global picture is probably not appropriate.



In addition, I find a lot of fault in blindly applying dose limit recommendations generated in the developed world to the entire world.  I just returned from a trip to Cambodia, where the average person does not live long enough to develop cancer from radiation, even at exposures much higher than 1 mSv/yr.  WIth landmines, disease, lack of clean water (even in the capital I could not drink tap water), poverty, and more, how can we expect the Cambodians to invest in radiation safety to meet criteria that are of arguable benefit in the developed world.  I would suggest that, in the developing world, there is a need to track sources, to regulate medical radiation use, but to spend most of their money on keeping citizens alive long enough so that cancer becomes a concern.



Please note that the above arguments apply regardless of the dose-response model we choose to feel is correct.  However, if LNT is not correct, they gain even more strength.  We have only a limited amount of money to be spent on making our society safer - we owe it to everyone to put those funds where they will do the most good.



Andy



P. Andrew Karam, Ph.D., CHP



Research Assistant Professor



Rochester Institute of Technology