From: "Westaway" <•••@••.•••>
To: "Westaway" <•••@••.•••>
Subject: Panel Affirms Radiation link to Cancer
Date: Fri, 1 Jul 2005 00:23:15 -0700
Panel Affirms Radiation Link to Cancer
By H. JOSEF HEBERT, Associated Press Writer 8 minutes
WASHINGTON - Even very low doses of radiation pose a
risk of cancer over a person's lifetime, a
National Academy of Sciences panel concluded
Wednesday. It rejected some scientists' arguments that
tiny doses are harmless or may in fact be beneficial.
The findings could influence the maximum radiation
levels that are allowed at abandoned reactors and
other nuclear sites. The conclusions also raise
warnings about excessive exposure to radiation for
medical purposes such as repeated whole-body CT scans.
"It is unlikely that there is a threshold (of
radiation exposure) below which cancers are not
induced," scientists said in the report.
While at low doses "the number of radiation-induced
cancers will be small ... as the overall lifetime
exposure increases, so does the risk," the experts
Scientists for years have debated how extremely low
doses of radiation affect human health.
Pro-nuclear advocates, as well as some independent
scientists, have maintained that the current risk
models for low-level radiation has produced more
stringent requirements than is necessary to protect
It is an issue in determining decontamination
requirements at abandoned reactors and at federal
The academy's panel stood by the "linear, no
threshold" model that generally is the acceptable
approach to radiation risk assessment. This approach
assumes that the health risks from radiation exposure
decline as the dose levels drop, but that each unit of
radiation - no matter how small - is assumed to cause
"The scientific research base shows that there is no
threshold of exposure below which low levels of
ionized radiation can be demonstrated to be harmless
or beneficial," said Richard R. Monson, the panel's
chairman. He is a professor of epidemiology at
Harvard's School of Public Health.
The panel said new and more extensive data developed
over the past 15 years only strengthen the conclusions
of the panel's last report, in 1990, on low-level
The scientists estimated that one out of 100 people
exposed to 100 millisievert of radiation over a
lifetime probably would develop solid cancer or
leukemia, and that half of those cases would be fatal.
It also said that 42 additional cancers can be
expected in the same group from other than low-level
A millisievert is a measurement of radiation energy
deposited in a living tissue. People absorb about 3
millisievent of radiation annually from natural
sources and 0.1 millisivert every time they get a
The report noted that exposure from a whole body CT
scan is about 10 millisievert, much higher than a
normal X-ray. That raised concerns about the frequency
of such medical diagnostics.
The report should not scare people away from nuclear
medicine, said Dr. Henry Royal, a professor of
radiology at Washington University in St. Louis. He
said most often the benefits of such tests and
treatments outweigh the risks.
But Royal also said that procedures such as CT scans
should be used to deal with a specific medical
problems and not part of annual medical screenings.
"You should not be exposed to radiation for
superficial reasons," Royal said in a telephone
Some anti-nuclear advocates said the study reaffirms
that stringent regulations are needed when cleaning up
abandoned nuclear sites or considering health risks
near nuclear power plants.
"The NAS panel puts to rest once and for all claims
that low doses of radiation aren't dangerous ...
nuclear advocates have been making this claim for
years" said Daniel Hirsch, president of Committee to
Bridge the Gap, a Los Angeles-based nuclear watchdog
Mitchell Singer, a spokesman for the Nuclear Energy
Institute, the industry's lobbying arm, said the
report "is a positive finding. It shows there is very
little risk of exposure from low levels of radiation."
The academy is a private organization chartered by
Congress to advise the government of scientific
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