>From my point of view, Jeroen's arguments seem to be based on emotion rather
than fact. I've been following this debate with interest, as I've always
been a proponent of green power and green ways. In the past, I was opposed
to nuclear power, but reading the facts that Dan has been posting has
convinced me that, if not green, nuclear is less dirty than our other
current forms of large scale power generation. I know that nuclear is
scary - but that's as much due to its newness and unfamiliarity as anything
else.
If you want to worry about radiation danger, here's a genuine peril to be
afraid of. I apologize for the length, but I could not find this article on
the Vancouver Sun or Ottawa Citizens' sites, so I scanned it and am posting
it here.
Radiation heightens as in-flight peril
[published in the Vancouver Sun, July 14, 2001]
When the passengers on an Air Canada flight from Vancouver trudged down the
walkway to board their Boeing 767 last Nov. 8, they had no idea a solar
storm would silently bombard them with radioactive particles throughout
their trip.
That afternoon, a series of explosions on the sun exposed airline passengers
to an unusually high dose of radiation. In the rare cosmic event, solar
flares sent highly charged particles from the sun hurtling towards the Earth
at half the speed of light.
When these protons began to collide with our atmosphere, about an hour
before the plane left the runway, the particles set off a shower of
neutrons, which rained down through the sky. With their long duration and
high altitudes, intercontinental flights are exposed to higher levels of
radiation than shorter, low-altitude flights, which are better shielded by
the atmosphere.
When the solar storm that began on Nov. 8 peaked the following afternoon,
travellers on flights cruising at 35,000 feet were enveloped in radiation
about 20 times the normal level, according to the space weather office at
the U.S. National Oceanic and Atmospheric Administration. Travellers aloft
during the peak of the storm absorbed radiation roughly equivalent to 10
chest x-rays taken at once.
The storm was of particular interest to Dr. Robert Barish, a medical
radiation specialist based in New York City, and author of The Invisible
Passenger: Radiation Risks for People Who Fly. When he thinks about those
Air Canada passengers on the way to Beijing, and the thousands of other
travellers in the air at the same time, he is haunted by one question: How
many were pregnant?
Most at risk, Barish believes, were women in the crucial first nine weeks of
their pregnancies.
"Is it possible that when the women who were flying start to have their
babies, there is going to be a higher incidence of birth defects?" As far as
Barish knows, no one is even looking into the question, despite the fact
that both regulators and the airline industry, are well aware of the effects
of "cosmic radiation".
In fact, regulatory bodies such as Transport Canada and the U.S. Federal
Aviation Administration are so concerned about the risks of in-flight
exposure to radiation that they are taking steps to protect aviation
workers, consumers have been left out of the discussions so far.
Transport Canada is preparing tough new regulations to limit the exposure of
pilots and flight attendants to radiation, including a strict limit on the
allowable exposure for pregnant workers. But the new rules, which are
expected to come into force at the beginning of next year, will do nothing
to protect passengers who travel often, or who are pregnant.
Although the degree of danger is under debate, Barish says the failure of
carriers and governments to inform the public about the dangers of cosmic
radiation is an "issue of morality."
At the very least, he says, passengers should be informed about the
increased risk of exposure during periods of intense solar activity.
Spectacular events such as last November's storm are still comparatively
rare. That flareup occurred at the peak of the sun's 11-year storm cycle,
and the explosions are expected to subside after this year.
Of greater concern to the aviation community is the ever-present ionizing
radiation not associated with solar flares. This cosmic radiation is caused
by neutrons and protons bouncing around the galaxy and through our
atmosphere. A small fraction of these radioactive particles reaches the
Earth's surface, but most are filtered out by the Earth's atmosphere before
hitting the ground.
As wide-bodied jets carry passengers higher and for longer periods of time,
exposure to cosmic radiation has increased dramatically. In the 1970s, a
flight from Montreal to Paris aboard a Boeing 707 would have flown at 22,000
feet.
Today, the same flight aboard an Airbus 340 could cruise as high as 41,000
feet. With the dose of in-fight radiation approximately doubling with every
6,000 feet of altitude, flyers on the same route today are exposed to about
eight times more radiation than they would have been 30 years ago.
The amount of ionizing radiation to which travellers are exposed also
depends on latitude: the closer a plane comes to the North Pole, the greater
the risk of exposure. In other words, a lengthy, high-altitude journey
between Vancouver and Tokyo exposes those aboard to far more radiation than
a short jump from Ottawa to Toronto.
This risk has recently been amplified the popularity of a new shortcut from
North America to Asia that takes jets directly over the North Pole, where
the radiation levels run three times higher than at lower latitudes.
Even before the transpolar routes, U.S. aviation authorities had been
advising airlines to educate their crews about the long term risks of
radiation exposure. In 1990, the FAA classified as radiation workers,
throwing them into the same regulatory pool as X-ray technicians and nuclear
power plant workers.
When there is no solar flare, a single flight from New York City to Tokyo
would expose travellers to about one tenth of one millisievert (one mSv),
the standard unit of radiation that the International Commission on
Radiological Protection sets as the maximum annual dosage for a member of
the public.
That means a frequent flyer who makes five round-trip flights from New York
to Tokyo in a single year could exceed the safe dosage. By comparison, the
shorter, lower-latitude Vancouver-Beijing flight, in times of normal solar
activity, exposes passengers to only 0.05 mSv.
The allowable levels for airline crews both in Canada and the U.S. are
higher than for the general public, because they are classified as radiation
workers and are understood to have consented to the risks of their
profession.
Transport Canada is planning to set a limit of 20 mSv per year for its
pilots and crew. There will also be an "intervention limit" of six mSv per
year, at which point workers must be reassigned to a job that will expose
them to less radiation (shorter, lower-altitude flights, for example).
In that respect, the Canadian rules will be tougher than those in the U.S.,
where the FAA limit recommends, but does not impose, the same yearly ceiling
of radiation exposure. But union representatives say the Transport Canada
maximum of 20 mSv per year is far too high, and they question the
"intervention limit" of six mSv.
The airline division of the Canadian Union of Public Employees, which
represents 8,500 flight attendants, points to research that indicates that
five of every 1,000 crew members will die of cancer caused by a relatively
low annual dose of only five mSv. That means that, even with the
intervention level of six mSv, an additional 45 CUPE members would
eventually die of cancer as a result of exposure to radiation, the union
projects.
Research on the health of pilots suggests a disturbing relationship between,
relatively low doses of cosmic radiation and cancer: A comprehensive 1996
study on the health of Air Canada pilots published in the American Journal
of Epidemiology found that, while pilots were in far better health overall
than most people, they had a substantially elevated incidence of acute
myeloid leukemia - a blood cancer strongly associated with radiation
exposure.
Over a 42-year period the data showed Canadian pilots had three times more
myeloid leukemia cases than are normally found in the general public. The
research included pilots who flew as early as 1950, before the age of high
altitude flights, so it is possible the study underestimated the impact of
radiation on cancer rates experienced by today's pilots.
The study's findings are all the more disturbing since pilots are generally
exposed to less radiation than other aviation workers, because the number of
hours they are allowed to fly is capped for safety reasons. The Air Canada
pilots' union estimates that the average pilot is only exposed to between
3.75 and five mSv per year.
By contrast, attendants who regularly staff transcontinental flights, for
example, are exposed to far greater levels of radiation. Under their current
contract, Air Canada attendants can spend as many as 85 hours a month in the
air - the equivalent of about 10 eight-hour, transcontinental flights a
month.
The aviation workers' union is also deeply concerned about flight attendants
who become pregnant. When the new Transport Canada regulations take effect,
pregnant crew members (including pilots) will be restricted to one mSv over
the course of their pregnancies. That will knock most out of active service
and force the airlines to find them other duties on the ground. It's a move
the flight attendants' union supports, as long as the affected workers
continue to receive full pay and benefits.
"We feel that pregnant flight attendants simply should not be flying," says
France Pelletier, director of regulatory affairs with CUPE's airline
division.
"But the carriers haven't moved on it, they don't have a procedure on what
they're going to do with pregnant women."
Pelletier, a member of Transport Canada's working group on cosmic radiation,
says she has been pushing for some kind of protection for members of the
public as well.
"Whatever applies to a flight attendant should apply to frequent flyers,
too," she says. "But is Transport going to be able to stop a frequent flyer
from carrying out her business? Are the carriers? I don't think so."
The long-term effects of flying are unknown when it comes to pregnant women.
However, it is generally agreed that a fetus is about eight times more
sensitive to radiation than an adult.
There has been virtually no research into in-flight radiation and pregnancy.
The National Institute for Occupational Safety and Health at the U.S.
Centers for Disease Control in Atlanta is conducting a large-scale study of
the reproductive health of flight attendants, to be published in 2002.
The two main factors under consideration are cosmic radiation and hormonal
disturbances caused by changing time zones frequently.
But Transport Canada says there isn't enough evidence yet to raise concerns
about the possible effects of cosmic radiation on airline passengers.
"Our studies have shown that passengers aren't really affected unless they
are flying day in and day out. Their exposure is not sufficient," says Art
Laflamme, Transport Canada's director general of commercial aviation.
"If it is a health issue for frequent flyers, we'll have to look at it. But
we're not aware of anyone who fits that category."
And experts agree that, for most travellers who fly a few times a year, the
amount of radiation on a high-flying transatlantic flight is negligible
under normal conditions. On a single flight, even pregnant travellers run
few risks.
Barish admits a single flight during normal solar activity is benign.
"You make a round trip from Ottawa to London to visit Granny, what's that
going to do to you? Probably nothing. In my opinion it's trivial," he says.
But those' who travel often - especially those who are pregnant - are more
likely to exceed safe radiation limits, Barish contends.
But neither the airlines nor the regulatory agencies do anything to warn
passengers.
Barish argues that people "must be given an opportunity to make an informed
decision" about whether or not to board a plane.
"There are hundreds of thousands of people who work with nuclear plants or
in hospitals' x-ray equipment," says Barish. "They know the risks. Flight
crews probably do, too. Pregnant women and frequent flyers should be
afforded the same opportunity."
Ottawa Citizen
