This item offers some satisfaction, after decades of struggle, for
my heroes such as John Gofman who have been stating this conclusion for 3
Panel Affirms Radiation Link to Cancer
June 30, 2005
By H. Josef Hebert, Associated Press
WASHINGTON -- The preponderance of scientific evidence shows that even very
low doses of radiation pose a risk of cancer or other health problems and
there is no threshold below which exposure can be viewed as harmless, a
panel of prominent scientists concluded Wednesday.
The finding by the National Academy of Sciences panel is viewed as critical
because it addresses radiation amounts commonly used in medical treatment
and is likely also to influence radiation levels the government will allow
at abandoned nuclear sites.
The nuclear industry, as well as some independent scientists, have argued
that there is a threshold of very low level radiation where exposure is not
harmful, or possibly even beneficial. They said current risk modeling may
exaggerate the health impact.
The panel, after five years of study, rejected that claim.
"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 chairman and a
professor of epidemiology at Harvard's School of Public Health.
The committee gave support to the so-called "linear, no threshold" model
that is currently the generally acceptable approach to radiation risk
assessment. This approach assumes that the health risks from radiation
exposure declines as the dose levels decline, but that each unit of
radiation -- no matter how small -- still is assumed to cause cancer.
"It is unlikely that there is a threshold below which cancer are not
induced," said the report, although it added that at low doses "the number
of radiation-induced cancers will be small." And it said cancers from such
low dose exposures may take many years to develop.
The panel, formally known as the Committee on Biological Effects of
Ionizing Radiation, or BEIR, generally supported previous cancer risk
estimates -- the last one by an earlier BEIR group in 1990.
Contrary to assertions that risks from exposure from low-level radiation
may have been overstated, the panel said "the availability of new and more
extensive data have strengthened confidence in these (earlier) estimates."
The committee examined doses of radiation of up to 100 millisievert, a
measurement of radiation energy deposited in a living tissue. A single
chest X-ray accounts for 0.1 millisievert, average background radiation 3
millisievert a year and a whole body CT scan delivers 10 millisievert..
The committee estimated that 1 out of 100 people would likely develop solid
cancer or leukemia from an exposure of 100 millisievert of radiation over a
lifetime with half of those cases being fatal.
The report noted that exposure from a whole body CT scan is much higher
than a normal X-ray, and it raised concerns about the frequency in which
such medical diagnostics should be used.
While medical radiation is often done for good reasons, said Monson,
"exposure to unnecessary radiation should be avoided."
Source: Associated Press