Radiation Effects Judged More Serious

Radiation is up to 16 times more dangerous than previously thought

By Marvin Resnikoff

1988

Radioactive Waste Campaign

Forty-three years after the atomic bombing of Hiroshima and 
Nagasaki, scientists are still trying to understand the health 
effects of exposure to radiation. A new study of Japanese bomb 
survivors by a joint Japanese-United States commission now raises 
the projected number of cancers, and has stirred up a hornets' 
nest of controversy.  Since the study of Japanese survivors has 
been the basis for radiation standards throughout the world, 
allowable radiation doses are expected to become more restricted 
as a re sult.

Following six years of careful documentation, the study by the 
Radiation Effects Research Foundation, which was released in 
September of last year, projects a higher number of cancers due 
to radiation than did a 1965 study by Oak Ridge National 
Laboratory in Tennessee.  The new study, which was jointly funded 
by the U.S. Department of Energy and the Japanese Ministry of 
Health, tracked 94,000 survivors of the Hiroshima and Nagasaki 
bombings. The increased results were attributed to two factors. 
Since 22 yea rs have passed since the last study, many additional 
cancers, including excess cancers due to radiation, were 
incorporated into the new study.  In particular, Japanese women, 
who were children during the bombings, are experiencing breast 
cancer rates in excess of the 1965 projections. The second basis 
for the increased cancer projections is a revision of how much 
radiation was received by each survivor.  In order to determine 
the effects of radiation, the joint commission had to estimate 
the amount of radiation received by the whole body and individual 
organs.  This required knowledge of the position and shielding of 
each survivor during the bomb blast.

But an extra unknown was the type and amount of radiation given 
off by each bomb. While much was known about the plutonium-type 
Nagasaki bomb, from atmospheric explosions at Trinity, New 
Mexico, the Pacific islands and the Nevada Test Site, the 
Hiroshima bomb was a one-of-a-kind uranium-235 weapon.  The 
higher number of cancers at Hiroshima was originally thought to 
be due to a greater emission of neutrons, which was thought to 
contribute up to 20% of the radiation dose. But, in fact, new 
calculations show that the extra neutrons did not exist, and that 
the types of radiation given off by the Hiroshima bomb were 
similar to those of the Nagasaki bomb.  Extra neutrons did not 
exist because of absorption of neutrons by heavy metal, as well 
as the humid conditions in Japan.  Previous estimates of 
radiation had been obtained by operating an unshielded nuclear 
reactor in the dry Nevada desert, conditions greatly different 
from Japan in the summer of 1945. The bottom line is that the 
increased canc ers at Hiroshima w ere due to gamma radiation, 
which is similar to X-rays but more penetrating, rather than 
neutrons. Assuming a direct correlation between amount of 
radiation absorbed and numbers of cancers generated, the new 
study, already under nuclear industry attack, shows that a 
radiation dose on the order of 260 person-rems will produce one 
fatal cancer in the exposed population. (A person-rem is the sum 
total of radiation doses to the population.) In comparison, the 
U.S. National Academy of Sciences accepts a standard of 5,000 
person-rems to effect a single fatal cancer in a population, and 
a 1977 United Nations st udy estimate put the dose at 10,000 
person-rems.  The average background radiation dose due to cosmic 
and terrestrial radiation is 100 millirems per year (1,000 
millirems equals one rem).

What international and national radiation standards-setting 
bodies will do with this new information is another question. The 
joint governmental study predicts a response to radiation dose 
roughly comparable to that projected for Hanford workers by 
independent researchers Mancuso, Stewart and Kneale.  The new 
results are roughly 16 times greater than presently accepted by 
establishment health physicists.  The United Nations radiation 
review body will incorporate the results at the end of this year. 
The International Commission on Radiological Protection stated at 
its September 1987 meeting that it will not begin to review the 
new information until 1990.  Not waiting for these bodies to act, 
the British National Radiological Protection Board recommended in 
November that whole body radiation doses to workers be made three 
times more restrictive.  If other national radiation bodies 
follow suit, the International Commission, long followed o n 
these matters, will begin to lose its influence.

The commission, composed of and influenced by nuclear industry 
representatives, has based its radiation standards, not only on 
the effects of radiation, but what is acceptable risk compared to 
other industries, clearly a political judgement.  Citizen groups 
would argue that no additional radiation (above background 
levels) is acceptable.  With the recent Japanese results, a 
further tightening of regulations would be expected (and) should 
be quickly implemented.

Marvin Resnikoff is staff scientist for the Radioactive Waste 
Campaign.  (1988)

Today, Resnikoff is the director of Resnikoff Associates.