[ExI] How dangerous is radiation?
johnkclark at gmail.com
Sat Jul 5 17:50:32 UTC 2014
Everybody agrees that huge amounts of radiation are harmful or fatal,
especially if received virtually instantaneously as in Hiroshima and
Nagasaki, but do more moderate amounts received much more slowly really
increase the likelihood of getting cancer and death years later? All our
public policy regarding nuclear power is based on the assumption that the
answer is yes, in particular it is assumed that the linear no threshold
(LNT) theory is correct. But is it? If death rates were always linear and
it was known that there was a 50% chance that when people were hit in the
head with a 3 pound iron ball moving at 20 mph they would die then if a
million people were hit in the head with a iron ball 6000 times less
massive you’d expect about 83 people to die, but in actuality a .008 ounce
BB moving at 20 mph wouldn’t even break the skin and nobody would die. It
doesn’t work for iron balls but is the LNT theory correct for radiation?
For obvious ethical reasons there isn't a lot of data on this subject but
there is some.
The natural background radiation of the Rocky Mountain states in the USA is
3.2 times higher than in the Gulf States, and yet the cancer death rate in
the Gulf States is 1.26 times HIGHER than in the Rocky Mountain states.
Radiologists spend their lives exposed to X rays, but they have less cancer
and a lower death rate than other physicians. People who became
radiologists between 1955 and 1970 had a 29% lower cancer rate and a 32%
lower death rate than non-radiologist physicians.
In 1983 steel bars used in the construction of 180 apartment buildings in
Taiwan were accidentally contaminated with Cobalt 60, it took about a
decade for this to be discovered and in the meantime 10,000 people were
exposed and some residents received as much as 500 millisieverts per year,
the average was 50; by comparison the natural background level is only 3.3
millisieverts. In a group of people that large you’d expect that 232 would
die from cancer by now, and if the LNT theory is true you’d expect 70
additional would die due to the excess radiation, so there should have been
302 deaths from cancer; but the astonishing thing is that only 7 people
died of cancer. In addition the LNT theory predicts there should have been
46 birth defects, but the actual number was 3.
A study was done on 71,000 people who were shipyard workers between 1957
and 1981, they were divided into 3 categories, a high dose group received
more than 0.5 rem, a low dose group that received less than that, and a
control group of shipyard workers that didn’t work on nuclear ships and so
received no excess radiation. Actuarial studies show that the high
radiation group had a 25% LOWER death rate than the control no radiation
group; the low radiation group had a bigger death rate than the high
radiation group but it was still lower than the zero radiation control
group of shipyard workers.
These results are the exact opposite of what the LNT theory predicts and
incredibly it seems to indicate that modest amounts of radiation received
over a long period of time can actually be beneficial.
John K Clark
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