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Nevada Atomic Tests Exposed Millions To Risk, Study Says
From: Stig_Agermose@online.pol.dk (Stig Agermose)
Date: Wed, 30 Jul 1997 07:41:46 -0800
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Found at:
http://www.nando.net/newsroom/ntn/health/072997/health7_29003.html
U. S. atomic tests in '50s exposed millions to risk, study says
Copyright ©1997 Nando.net
Copyright ©1997 N.Y. Times News Service
WASHINGTON (July 29, 1997 12:51 p.m. EDT) -- Atmospheric nuclear bomb
tests in Nevada from 1951 to 1962 exposed millions of American children
to large amounts of radioactive iodine, a component of fallout that can
affect the thyroid gland, the National Cancer Institute said on Monday.
The releases were larger than earlier estimates, and at least 10 times
larger than those caused by the 1986 explosion at the Chernobyl nuclear
plant in Ukraine. Under federal rules implemented in 1992 to deal with
accidents at nuclear power plants, some of the tests would require
protective actions like moving cows to shelter, or dumping their milk
that would tend to have high concentrations of radioactive iodine. But
no such precautions were taken at the time of the Nevada tests.
The cancer institute could not say whether any cases of thyroid cancer
were caused by the fallout. But several experts said the levels of
exposure could justify special monitoring for some people --
particularly those who were children in the 1950s and 1960s.
The information is from a 100,000-page study by the cancer institute
that was ordered by Congress in 1982. The study was begun in 1983 and a
draft report was completed in 1994. It has been undergoing revisions
and rewriting since then.
A summary of the study, prepared for internal use at the Department of
Energy and obtained by The New York Times, says that according to
formulas in international use for calculating radiation damage, the
doses were large enough to produce 25,000 to 50,000 cases of thyroid
cancer around the country, of which 2,500 would be expected to be
fatal. But the accuracy of those formulas is not certain, experts at
the Department of Energy and elsewhere say, because the data on
exposures at that level are limited.
The Department of Energy did not play a role in the study beyond
providing some of the raw data. The department is a successor to the
Atomic Energy Agency, which detonated most of the bombs.
The leader of the cancer institute study, Dr. Bruce Wachholz, said it
was not clear that the exposures were high enough to increase the
cancer risk. Studies of people in Utah immediately downwind from the
test site did not find a clear association with thyroid cancer,
Wachholz said.
The new study says the average dose to the approximately 160 million
people living in the country in that period was 2 rads, a unit that
stands for "radiation absorbed dose" and refers to the amount of energy
absorbed by flesh. But, the cancer institute said on Monday, people
living in "Western states to the north and east of the test site"
received doses averaging 5 to 16 rads. Children aged 3 months to 5
years had doses 10 times higher, the institute said.
The main pathway for radioactive iodine exposure is through milk, which
children consume in larger quantities than adults, especially in
comparison to their body weight. When the contaminated milk is
consumed, the human body delivers the iodine to the thyroid, where it
can cause the development of cancerous nodules.
In addition, children's thyroids are smaller, and an equal quantity of
the radioactive iodine in a smaller gland would deliver more energy per
kilogram of tissue.
In contrast to the 50 to 160 rads those children are believed to have
received, federal rules for nuclear power plant accidents call for
taking protective action when the dose to human thyroids is anticipated
to reach 15 rads. And another government agency, a branch of the Public
Health Service, studying thyroid exposures around a government nuclear
bomb factory at Hanford, Wash., has recommended medical monitoring for
adults who absorbed 10 rads or more as children.
"There's a reasonable association" between radioactive iodine exposure
and cancer, said Dr. Robert Spengler, the assistant director for
science of the agency that made the recommendation, the Agency for
Toxic Substances and Disease Registry. He said the association was
demonstrated by a growing body of literature, from people in the
Marshall Islands, where tests were also conducted, and elsewhere.
But Wachholz said "we really don't understand the dose-effect
relationship" for radioactive iodine.
He said studies by his agency in the 1980s of 2,500 adults in Utah who
had also been studied as children in the 1960s had not found a basis
for a firm statistical finding of an association.
"I think it raises some serious questions," said E. Cooper Brown,
chairman of the National Committee for Radiation Victims, a coalition
of groups that includes soldiers exposed in the field, uranium miners
and people who lived downwind of the test site. "I don't think you can
say, 'aha, definitely.' That would be stepping way out of bounds. But
you can't just shrug your shoulders and say, ah, it probably didn't
hurt anybody."
The iodine form in question, iodine 131, is created when uranium or
plutonium is split, in a reactor or a bomb. It is intensely
radioactive, losing half of its radioactivity every eight days, meaning
that within a few weeks it has disappeared. But if the release is large
enough, it can be carried thousands of miles in the upper atmosphere
and come to earth with enough energy remaining to deliver substantial
doses.
The cancer institute said that its dose estimates were subject to "a
large degree of uncertainty" because they were based on a small number
of radiation measurements made at the time. One factor in estimating
the dose is calculating the average amount of milk consumed, and its
average time to market.
The institute said it had accomplished two of the goals that Congress
set for it in 1982: developing a way to estimate the dose, and making
the estimate. The third, assessing the risk of cancer from the
exposures, is still to be finished, the institute said. It released the
information after several days of reports about the contents of the
study, which it plans to complete by October.
The cancer institute warned doctors in 1977 that the incidence of
thyroid cancer had risen, to 3.9 cases per 100,000 population in a
1969-71 survey, from 2.4 cases in 1947. Among white people aged 20 to
35, the increase was "twofold to fourfold," the institute said,
referring to people who were children at the time. But the cause is not
clear; doctors had been using radiation to treat everything from acne
to deafness from the 1920s on.
Thyroid cancer is a relatively rare disease. According to the American
Cancer Society, it will kill about 1,230 people this year, out of a
total 560,000 deaths from all forms of cancer. The disease has a cure
rate of 90 percent to 95 percent, although patients require drug
therapy for the rest of their lives.
The size of the doses being estimated surprised experts.
"This is especially tragic, because it could have been avoided," said
Arjun Makhijani, the president of the Institute for Energy and
Environmental Research, a nonprofit group based here that specializes
in nuclear weapons. "They knew when the tests were and chose not to
warn the population, and they located the test site in the West,
knowing there would be fallout over the whole country."
The Department of Energy summary contrasted the new estimate of
radiation dose to an estimate submitted to the old Joint Committee on
Atomic Energy in 1959, which was .2 to .4 rads, or more than 100 times
smaller than the average now cited for Western states.
The new study attempts to reconstruct the effects of 90 blasts at the
Nevada Test Site, which was used by this country and Britain, across
the 3,070 counties in the 48 contiguous states.
The study found Iodine 131 "hot spots" from a series of tests in 1953
that included large areas of New Mexico, Oklahoma, Iowa, Wisconsin, New
York and Massachusetts, including one event in the Troy/Albany area.
That event was briefly described by the Defense Nuclear Agency in 1982,
when it said people living there may have received a dose of 2 rads to
the whole body, and was widely reported at that time.
The Department of Energy summary of the new study, however, puts the
Troy/Albany event in a new light, since 2 rads would not necessarily
have required protective action under the rules that would be adopted
later. But the thyroid dose there was high enough to have required
protective action, had those rules been in effect at the time, the
summary said.
By MATTHEW L. WALD, N.Y. Times News Service
Copyright ©1997 Nando.net
Index: Nevada Test Site
Created: Jul 30, 1997
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