As of this morning [18 March 2011], the casualty count in Japan from last Friday’s tsunami stands at 6539. As another 10,250 persons are still listed as missing, the death toll is almost certain to climb. These numbers place last week’s event ahead of the 1995 Kobe earthquake in Japan’s annals of lethal disasters. 380,000 people are still in 2200 shelters; 100,000 of them are evacuees from the area surrounding the Fukushima nuclear power plant, where workers are still attempting to bring the situation at stricken reactors and spent-fuel cooling ponds under control.
A few years ago, one of my esteemed colleagues published a paper entitled “Reflections on the Proliferation of
Threats”, the core argument of which was
that governments display a lamentable tendency to conflate threats driven by
human intention with challenges deriving from the often very deadly, but quite
insensate, environment in which we live. One of the chapters of this
note, entitled “A sense of proportion”, focussed more closely on a peculiarity
of human nature: how very bad we can be at assessing risk. He offered
urban mortality rates as a case in point. According to a study that had
been cited by the IPCC, as a consequence of climate change New York City could
be expected to experience an additional 500-1000 deaths due to heat over the
period 2000-2050. This amounts to 10-20 climate-change-related deaths per
year for the Big Apple. Data from the Centres for Disease Control and New
York’s own Department of Public Health offer some perspective on that
number. Of the more than 55,000 people who died in NYC in 2006, for
example, more than 1000 died from complications from diabetes, more than 1500
from alcohol-related causes, and 1000 in infancy. 100 people die every
year in New York in construction accidents - and yet New Yorkers still build
buildings. 21,000 die from heart disease, and 13,000 from cancer,(Note A)
and yet New Yorkers still eat Big Macs and smoke Marlboros. Such figures,
the paper notes, puts the risk of excess mortality from climate
change into appropriate context.(Note B)
I raise the issue of risk assessment in
the context of the death toll from last week’s tsunami because of the ongoing
drama over events at the Fukushima nuclear power plant and the media-driven
frenzy over radiation fears, both in Japan (where at least there is some
factual basis for worry, however slender it may be) and elsewhere around the
world (where there is no basis whatsoever for the panic). As I write
this, people in Canada and the US are emptying pharmacies of potassium iodide
pills, and you can’t get a Geiger counter for love or money. So let’s
take a look at how big the risk really is, shall we?
According to World Nuclear News, the normal
annual allowable radiation dose for nuclear power plant workers is 20
millisieverts (mSv) per year; after receiving that much radiation, no further
nuclear activities are permitted. In practice, most workers receive much,
much less. In emergency situations, that limit may be increased 100
mSv. This is the point at which health effects from exposure become
possible. To make this more clear, below 100 mSv per year, there is no
detectable statistical relationship between radiation exposure and human
health; above this level, a statistical relationship begins to become
apparent. Due to the scale of the disaster at Fukushima and the
importance of controlling the situation, Japan’s Nuclear and Industrial Safety
Agency has allowed the maximum exposure for on-site personnel to be increased
to 250 mSv.
How bad is that? Well, as of yesterday, one week into the crisis, this is
how bad it was:
·
One Tepco worker working within the reactor
building of Fukushima Daiichi unit 3 during “vent work” was taken to hospital
after receiving radiation exposure exceeding 100 mSv, a level deemed acceptable
in emergency situations by some national nuclear safety regulators.
·
Nine Tepco employees and eight subcontractors
suffered facial exposure to low levels of radiation. They did not require
hospital treatment.
·
Two policemen were decontaminated after being
exposed to radiation.
·
An unspecified number of firemen who were
exposed to radiation are under investigation. (Note C)
Yes, you read that right. One Tepco
worker has received a higher than 100 mSv dose. That’s it. That’s
all.
How about radiation levels? Well, a
couple of days ago the Tokyo office of Denphone has set up a web-enabled
real-time radiation monitor showing 4-hour, 24-hour, and 1-week radiation level
readings. Here’s the 1-week chart:
Figure 1 – Denphone Tokyo Realtime radiation monitoring
chart; March 17-18 2011
For the past two days the average radiation
level at the Denphone office in Tokyo has been below 30 micro-Roentgens per hour;
the max has not exceeded 50, and the levels are dropping. Normal
background radiation, by the way, is 23 micro-Roentgens per hour.
(Sieverts is the modern unit replacing Roentgen-equivalent-man, or REMs).
If radiation levels were to remain at 30 micro-Roentgens per hour, the annual
additional dose a Tokyo resident would receive would be 61 milliRems or .061
Rems. Since 1 Sievert is 100 Rems, this would be an additional annual
dose of 0.61 mSv, or .0016 mSv per day.
To put that into perspective, consider the
following:
·
sleeping next to another human for 8 hrs: .0005
mSv. So the additional annual dose rate would be the same as sleeping
next to 3 humans for 8 hours per day.
·
a mammogram is 3 mSv
·
a chest CT scan is 6-18 mSv
·
cosmic radiation at sea level is .24 mSv/year
·
terrestrial radiation (from the ground) is .28
mSv/year
·
radiation from the granite in the US Capitol
Building: .85 mSv/year
·
airline crew on New York - Tokyo runs accumulate
an additional 9 mSv/year
·
smoking 1.5 packs of cigarettes per day: 18-65
mSv per year
In other words, someone who smokes a pack and a
half a day will receive up to 100 times more excess radiation per year
than the folks in Tokyo are absorbing at present. To say nothing of
the further dangers of smoking, of course.
Radiation is a complicated phenomenon and is
present in so much of the world around us that we never think about it.
For example, the dose from eating a banana is .0001 mSv. So if you eat a
banana a day, you’re voluntarily absorbing more radiation every year than you
would get from 7 dental X-rays.(Note D)
How about North America? Are we in any
danger? Well, there’s a network of radiation detectors in the US (and you
can join it, if you want to, and if you can buy a real-time web-enabled Geiger
counter, which at present you can’t because the companies that make them are
sold out). Geiger counters measure radiation in counts-per-minute (CPM)
of alpha and beta particles. The normal background level is 25-75
CPM. Here’s the US as of 7:04 EST this morning:
Figure 2 – Realtime radiation results for the
continental US as of 0404 PST, 18 March 2011
The numbers on the West Coast are revealing;
16-34 CPM, low on the normal range for background radiation. (2004 is the
patent date) Why is Denver so high, you ask? Probably because of
its altitude; there’s less atmosphere to block cosmic radiation.
So I’d reflect before popping too many
potassium iodide pills. They work by filling your thyroid gland with
non-radioactive iodine so that it can’t absorb highly radioactive iodine-131 -
but the potential radiation from Fukushima, if any ever gets here, won’t
be in the form of I-131 anyway. Which sort of makes you wonder why US
Surgeon General Regina Benjamin told people to stock up on them...but that’s a
problem for another day.
Bottom line, there has been no significant
radiation from the Fukushima disaster to reach North America. Additional
radiation levels in Tokyo are two orders of magnitude lower than the
radiation to which the average Japanese is exposed from cigarette
smoking. And even in the heart of the crisis, at the Fukushima power
plant itself, there has to date only been one individual exposed to more than
100 mSv of radiation - and he absorbed less than he would if he were a
3-pack-a-day man. Could it get worse? Yes, of course it
could. But so far it hasn’t. A meltdown, partial or complete, is
possible. “Chernobyl” (let alone “The China Syndrome”) is not.
Earlier this morning, Japan rated the Fukushima
situation as “equivalent to 3-Mile Island”, which - as Greenpeace, the Union of
Concerned Scientists, CNN and other media outlets keep reminding us - was the “worst
nuclear accident in US history”.(Note E) There were no deaths or injuries
either at the plant or in the local community as a result of the 3-Mile Island
partial meltdown.(Note F) As “worst accidents” go, that’s not so bad -
especially when you consider that, according to the CDC mortality data
reported in Peter’s paper, it is statistically probable that 131 Americans
will die in traffic accidents, and 34 in gun homicides...today.
Over the past week, the only death at the
Fukushima power plant was a crane operator who succumbed to injuries received
in the initial earthquake. Meanwhile, 25 of the 100,000 people
evacuated from the Fukushima area have died in the shelters to which they were
moved. Sometimes the cure is worse than the disease. Idiotic
headlines comparing Fukushima to Chernobyl or evoking the dreaded “China
Syndrome” aren’t helpful, and they distract scarce recovery efforts from the
real problems. And, depressingly, they show how bad
people continue to be at assessing probabilities, costs and
risks.
Now, to go buy a LottoMax ticket!
Cheers,
//Don//
NOTES
A) See Peter Archambault, Reflections on the Proliferation of Threats, DRDC CORA TN 2009-020, June 2009, 9-10.
NOTES
A) See Peter Archambault, Reflections on the Proliferation of Threats, DRDC CORA TN 2009-020, June 2009, 9-10.
B) The study predicting excess heat-related mortality
(Kalkstein and Greene, 1997) assumed that the IPCC model predictions for future
temperature regimes were accurate and that temperatures would continue to
rise. The average global temperature has in fact fallen since Kalkstein
and Greene published their study.
D) This is because bananas, as we all know, are a
major source of potassium, and potassium-40 is a highly radioactive
isotope. Crates of bananas regularly set off radiation detectors at US
ports and customs facilities. By the way, if radiations cares you, then
stay the hell away from Brazil Nuts; pound for pound, they’re about 30 times as
radioactive as bananas.
E)
[http://www.cnn.com/2011/WORLD/asiapcf/03/18/japan.nuclear.reactors/index.html?hpt=T1#]
F)
[http://www.rps.psu.edu/probing/nuclearpower.html].
