A continuation
of Conventional Wisdom posted August
8, 2011.
“Listen up, Julie.
I’m going to teach you that exposure to small amounts of radiation won’t
hurt you. In fact, it may even be
good for you, even at the levels used for diagnostic purposes such as computed
tomography (CT) scans. Recent
research has shown that living in a radiation-deficient environment stunted the
growth of a protozoan. And living
in a radiation background that is several times our present level should
improve our health and longevity. (Google Sir
Samurai T. D. Luckey.)”
“Get off it, Curmudge!
I’ve been taught since I was a child that all radiation is
dangerous. Old men are supposed to
dream dreams (Acts 2:17), but isn’t this one pushing the envelope? And besides, blogs are too brief to
teach anything. The most they can
do is inspire the reader to learn more.”
“Right as usual, Julie. Our teaching—I mean exposure—to this topic began over a year
ago (August 8, 2011) in our posting on Conventional
Wisdom. At that time we
still had a sponsor and had to tread softly on controversial topics.”
“Hooray! Vive
l’indépendence! Now we can
tackle controversial issues head-on.”
“Whoa, Ms. Enthusiasm.
As I said, we introduced today’s topic, the linear no-threshold (LNT)
concept, in 2011. To avoid repeating everything, let’s all go back and read the
Conventional
Wisdom posting.”
[Blog delayed 10 minutes for Jaded Julie and readers to read
old posting.]
“Now I remember,
Curmudge. According to the linear
no-threshold theory a plot of cancer occurrence vs. exposure, based on high
levels of exposure to radiation, could be extrapolated to the origin, i.e.,
there was no threshold below which there was no effect.”
“That’s it, all right.
But extensive research has shown the LNT theory to be invalid. We cited some of it in our earlier posting,
and we’ll list more books and papers today. If our readers study the documents that we cite, most should
agree that the LNT theory has become outmoded. However, there will likely be some who will cling to the LNT
dogma.”
“Also in our Conventional
Wisdom posting there were references suggesting that exposure to low-level
radiation imparted a protective effect against cancer. Will we discuss that also?”
“We surely will, Julie, but it may require more than a
single posting. There’s so much
information on these topics that we’ll only have room in the blog to mention
authors and brief summaries.
Complete references are in Hiserodt’s book, discussed below. And to examine these documents
critically, a reader will need to become familiar with the units used to
measure radiation, which we don’t have space to cover.”
“But Curmudge, we’ll need to use some numbers, and readers will require a few units to even gain a
seat-of-the-pants understanding of our story.”
“Good observation, Julie. Here are some common abbreviations and units:
Abbreviations: m = milli or 1/1000; c = centi or 1/100.
Rem is effective dose in U.S. units; sievert (Sv) [gray (Gy)
is equivalent] is effective dose in international units. 1 Sv = 100 rem. 1 cSv = 1,000 mrem.”
“How about providing a frame of reference?”
“Here are some ballpark values:
Typical background radiation (cosmic, terrestrial, radon,
medical) in the U.S. = 300 mrem (0.3 cSv) per year. Background in Denver = 600 mrem (0.6 cSv).
Maximum permissible exposure for a nuclear worker = 5,000
mrem (5 cSv) per year.
Acute exposure (1-2 days) to cause radiation sickness =
100,000 mrem (100 cSv).”
A single computed tomography (CT) scan = 1,000-5,000 mrem
(1-5 cSv).”
“Thanks, Old Guy.
Now we all should be on the same page. Shall we begin our discussion by mentioning the books on
this subject that are available?”
“To easily obtain the most information at a reasonable price
($5.91 from Amazon), I recommend Ed Hiserodt’s Underexposed (subtitled What
if radiation is actually good for you?) (2005). Despite its easy-reading appearance, the scientist or
nonscientist will likely agree that much of the story is there, and that it is supported by a comprehensive Amazon
review by Jay Lehr. Books with
more detail and a much higher price include Radiation
Hormesis by T. D. Luckey (1991) and Radiation
Hormesis and the Linear-No-Threshold Assumption by Charles L. Sanders
(2009). These books are well
documented with peer-reviewed literature.
Luckey’s two books—an earlier one was published in 1981—contain over
2,00 citations.”
“Well Curmudge, I can guess which book a very familiar
tightwad bought. Prof.
Luckey is revered in Japan, where they accorded him the honorary title of Samurai. This can be confirmed by ‘googling’ Sir Samurai T. D. Luckey, where many of the teachings of this blog
are also supported. By the way, I
noticed that the books by Luckey and Sanders have hormesis in their titles.
Perhaps you can tell us what hormesis means.”
“It’s the protective effect mentioned by Tubiana in Conventional Wisdom. And more generally, it’s the phenomenon
where something that is harmful at high doses is helpful at low doses. Examples are many trace metals,
vitamins, and even water. So to
proceed, in addition to the papers cited in our Conventional Wisdom posting (those by Vaiserman, Tubiana et al.,
and Scott et al.) the following tend to refute the LNT theory and support the
radiation hormesis concept. We’ll
start with the early observations, made mostly by Japanese scientists, on
survivors of the atomic bomb attacks on Hiroshima and Nagasaki.”
“Chapter 15 in Hiserodt shows plots of cancer deaths vs.
exposure. Because plots are hard
to show in this blog, I trust, Old Guy, that you can describe them.”
“A ‘hockey stick’ plot of effect vs. exposure (with blade to
the left coinciding with data on unexposed controls) would have refuted the LNT
theory. These plots were shaped like field
hockey sticks with blades drooping below controls, thus demonstrating radiation
hormesis (fewer deaths than controls) below around 10 cGy.”
“Curmudge, with those exciting findings published in Health Physics and seemingly ignored
since 1987, let’s take a few days to search the books further and find some
more data. Sayonara.”
Kaizen Curmudgeon