ntamination from long-lived radioactive isotopes like strontium-90 or
cesium-137, which can be concentrated through the food chain and
incorporated into the body. The damage caused would be internal, with
the injurious effects appearing over many years. For the survivors of
a nuclear war, this lingering radiation hazard could represent a grave
threat for as long as 1 to 5 years after the attack.

B. Worldwide Effects of Fallout

Much of our knowledge of the production and distribution of
radionuclides has been derived from the period of intensive nuclear
testing in the atmosphere during the 1950's and early 1960's. It is
estimated that more than 500 megatons of nuclear yield were detonated
in the atmosphere between 1945 and 1971, about half of this yield being
produced by a fission reaction. The peak occurred in 1961-62, when a
total of 340 megatons were detonated in the atmosphere by the United
States and Soviet Union. The limited nuclear test ban treaty of 1963
ended atmospheric testing for the United States, Britain, and the
Soviet Union, but two major non-signatories, France and China,
continued nuclear testing at the rate of about 5 megatons annually.
(France now conducts its nuclear tests underground.)

A U.N. scientific committee has estimated that the cumulative per
capita dose to the world's population up to the year 2000 as a result
of atmospheric testing through 1970 (cutoff date of the study) will be
the equivalent of 2 years' exposure to natural background radiation on
the earth's surface. For the bulk of the world's population, internal
and external radiation doses of natural origin amount to less than
one-tenth rad annually. Thus nuclear testing to date does not appear
to pose a severe radiation threat in global terms. But a nuclear war
releasing 10 or 100 times the total yield of all previous weapons tests
could pose a far greater worldwide threat.

The biological effects of all forms of ionizing radiation have been
calculated within broad ranges by the National Academy of Sciences.
Based on these calculations, fallout from the 500-plus megatons of
nuclear testing through 1970 will produce between 2 and 25 cases of
genetic disease per million live births in the next generation. This
means that between 3 and 50 persons per billion births in the
post-testing generation will have genetic damage for each megaton of
nuclear yield exploded. With similar uncertainty, it is possible to
estimate t