From: jgd@rsiatl.UUCP (John G. De Armond)
Newsgroups: sci.energy
Subject: Low level radiation risks if any
Keywords: Nuclear/health/radiation/threshold
Message-ID: <1504@rsiatl.UUCP>
Date: 21 Feb 90 04:04:07 GMT

chidsey@smoke.BRL.MIL (Irving Chidsey) writes:

>In article <1990Feb20.005507.10651@agate.berkeley.edu> sachs@tanner.UUCP (Rainer Sachs) writes:
><In article <778@noe.UUCP> gary@noe.UUCP (Gary Evans (N6PAW)) writes:

[A discussion regarding the BEIR IV report deleted.]

><>To summarize a portion of the summary: NO THRESHOLD, LINEAR FUNCTION
><
><This summary is overstated.  Note the careful wording "do not
><contradict the hypothesis ...".
><
><Quite possibly, according to current ideas:
>< (a) the effects of ionizing radiation as far as killing cells
><or causing mutations has a significant linear portion.
>< (b) the effects of overall damage as far as causing cancer may
><well be quadratic or of higher order in the overall damage, at
><least for many kinds of cancer (e.g. if one needs to turn on two
><different genes, one for uncontrolled growth, another for the
><ability to move to new locations in the body)
>< (c) In case (b), if, e.g., chemical damage is much more
><predominant than radiation damage, this would still mean that
><as a function of radiation damage *alone* cancer is linear.  But
><it would also mean than whenever radiation damage is a large
><fraction of overall damage, cancer is super linear in radiation
><damage.
>< (d) My preferred summary would be: for cell killing or mutation,
><there is probably no threshold, even for low LET radiation;
><for cancer induction, the situation remains doubtful.

I'll argue another possibility below.

>	I have read that the epidemiology of many forms of adult cancer is
>consistant with the hypothesis that n separate events are needed to initiate
>a cancer where n seems to be more than 1 and less than 5 or so.  There also
>may be one or more effective repair mechanisms in the event of DNA damage,
>and the immune system may be able to recognize some cancers as foreign and
>so attack them.  -- Note all the weasel words!

>	If these hypotheses are true, then carcinogenic effects are likely to
>be non-linear at low dosages, and may even have a threshold.  -- Note, more
>weasel words!

A threshold is probably the most conservative model in light of current
knowledge.

>	IF there is a consistent threshold for most, or nearly all , cancers
>that result from some carcinogen, then it may be reasonable to recognise
>that threshold in our regulatory process.  -- Note, even more weasel words!

The regulatory process has always recognized a threshold effect and has
relatively recently embodied it in the "de minimus" concept.  This
concept, which is becomming law, is that there is a level of radiation
exposure below which there are no effects.  Thus no regulation of these
levels is indicated.

>	Hence, the fuss about thresholds.  Some believe in them, some don't.

>	In some cases the belief, or disbelief seems to be determined more
>by doctrinaire position than by examination of the admittedly scanty and
>rather inconclusive evidence.

Not really, not anymore.  There is more and more evidence accumulating
that there are actually beneficial effects associated with low level
radiation exposure.  Among the mechanisms postulated are the following:

*  Small damage to DNA stimulates the cell to repair the damage before it
would do so normally.  This damage may be cumulative and be caused by
many agents, not just ionizing radiation.  In other words, a radiation
absorption event in a cell may stimulate it to repair itself before
the damage propagates through mitosis.

*	Incipient cancer cells are more sensitive to radiation destruction
than normal healthy cells. (the reason radiation therapy works.)  Cancer
cells are believed to form and be destroyed as an ongoing process in the
body.  In agreement with the "n events" theory  Rainer mentioned above,
the only time a cancerous cell forms a tumor is when n events occur in  the
correct sequence.  A cell destroyed by a radiation absorption event cannot
participate in the "n event" Russian Roulette.

*	The free radicals released by the absorption of radiation may, in low
doses, stimulate the cell in positive ways toward healing.  It is consistent
with other cellular irritants to find that low concentrations are beneficial
while high concentrations are harmful.

The evidence of the beneficial effects of radiation, known as Radiation
Hormesis, has become so strong that the Health-Physics society held its
first Symposium on Radiation Hormesis and published the proceedings
thereof.  These proceedings make very interesting study and tend to make
an objective person reconsider many long-held beliefs regarding
radiation effects.

While neither the Health-Physics Society, the NCRP nor the ICRP is ready
to take a positive stand on the subject, the evidence continues to mount
to the point that a conclusion becomes mandatory.  I will further note that
all health-physics protection criteria is still based on the linear
risk model. This is unlikely to change because it results in a large
degree of concervatism in the protection of workers.

What radiation hormesis WILL have an effect on ultimately will be the
regulatory process regarding radiation exposure to the public.  Current
regulations limit exposure to the public from man-made source to a
level far below natural background.  I expect and hope that this regulation
will be relaxed as evidence mounts that the regulation actually is slightly
harmful to the "protected" population.

Radiation hormesis will probably never be proven nor will there ever
be a hard number that represents the ideal radiation exposure dose simply
because control subjects (people exposed to zero radiation) do not
exist.

On a related topic, today's paper headlined a presentation made to the
American Association for the Advancement of Science by Dr. Robert J.
Scheuplein, Director of the office of Toxicological Sciences at the
US Food and Drug Administration.  Dr. Scheuplein presented the
results of an extensive study of natural carcinogens.  He noted that
the natural carcinogens in common food represents over 98% of the
risk humans face from cancer.

The most hazardous substance from a cancer perspective is common fat.
Hard links have been established between fat in the diet and several
tumors.  Other natural toxins and carcinogens include:

*	Genetically active substances that result from cooking high protein
	foods.

*	Urethane, a natural byproduct of fermentation.

*	Mycotoxins produced by molds in food.

*	Aflatoxins found in corn and peanuts.

*	Nitrates, Nitrites  and fungi in smoked or salted fish and pickled
	vegies may cause cancers of the digestive tract.

*	Blackened and grilled fish and meat often contain the carcinogen
	nitropyrenes.

*	Many spices such as cloves and cinnamon contain known toxins in
	relatively high concentrations.

*	Common vegies contain one or more of the following carcinogens:
	d-limonene, (oranges).
	psoralens (celery)
	hydrazines (mushrooms)
	nitrates (spinich)

He further noted that the total risk of dying from cancer is about 7.7%.
Subtracting all man-made risks (radiation, chemicals, etc), the risk
becomes 7.6%!  In other words, ALL the things the eco-terrorists represent
at most, perhaps 0.1% risk which is hidden in the noise of natural sources.
Dr.Scheuplein noted that only a 1% reduction in the fat content of an
average human's diet would completely obscure any theoretical benefit of
eliminating ALL man-made cancer risks!

A quote from the good doctor should perhaps be etched in the foreheads
of some segments of our society known for their hand-wringing and
finger pointing:

	"Most of the risks are people's personal choices.  They are not
	imposed on people by corporations.  Apparently that's a hard lesson.
	People want to blame somebody?"  [ and find a deep pocket ]

This, folks, is something to think about the next time a Greenie
tries to tell you that some nuclear radiation facility MIGHT expose you
to a cancer risk and thus should be banned.

John

From: jgd@rsiatl.UUCP (John G. De Armond)
Newsgroups: sci.energy
Subject: Re: Low level radiation risks if any
Keywords: Nuclear/health/radiation/threshold
Message-ID: <1531@rsiatl.UUCP>
Date: 28 Feb 90 07:00:05 GMT

john@anasaz.UUCP (John Moore) writes:

>In article <1504@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. De Armond) writes:
>]	"Most of the risks are people's personal choices.  They are not
>]	imposed on people by corporations.  Apparently that's a hard lesson.
>]	People want to blame somebody?"  [ and find a deep pocket ]
>]
>]This, folks, is something to think about the next time a Greenie
>]tries to tell you that some nuclear radiation facility MIGHT expose you
>]to a cancer risk and thus should be banned.
>]
>John, thanks for another excellent posting. However - I have a question
>about the good doctor's numbers: where does smoking come in?

John,

I went back and looked at the article after I read your question.  It is
very interesting that smoking was not mentioned at all.  I find that
very fascinating.  Perhaps the reason is that when one looks at all the
causes of death other than natural causes (where the body just gets tired
one day and quits), the risks from things we consider natural and harmless
such as eating fat mask the risk from smoking.  While the cancer rate
among those that smoke is frightening, I suspect, and this is purely
speculation, that the smoking risk, when applied to the whole population,
is relatively small.

My philosophy has always been one of moderation.  Though it is human
nature to deny the existance of death as an end process in our lives,
the fact remains that something WILL kill us, statistically between
approximately 60 and 80 years of age.  I believe that the 80-20 rule
applies here too.  I avoid large risks, eat moderately healthy, don't smoke,
wear a seat belt religiously, get a moderate bit of exercize, don't store
radiographer's sources in my hip pocket, and keep my weight moderately under
control.  I believe that such caution in moderation (the 20% effort) will
return the most benefits (80% or better of the best lifespan.)  After
all, I could go to extremes regarding all risks, deprive myself of most
of life's pleasures and still die early from a) a fluke, b) damage due to
participating in the health fad of the day or c) a random risk whose number
came up.

John