emitter with a half-life of 5,730 years. Both are taken up through the
food cycle and readily incorporated in organic matter.

Three types of radiation damage may occur: bodily damage (mainly leukemia
and cancers of the thyroid, lung, breast, bone, and gastrointestinal
tract); genetic damage (birth defects and constitutional and degenerative
diseases due to gonodal damage suffered by parents); and development and
growth damage (primarily growth and mental retardation of unborn infants
and young children). Since heavy radiation doses of about 20 roentgen or
more (see "Radioactivity" note) are necessary to produce developmental
defects, these effects would probably be confined to areas of heavy local
fallout in the nuclear combatant nations and would not become a global
problem.


A. Local Fallout

Most of the radiation hazard from nuclear bursts comes from short-lived
radionuclides external to the body; these are generally confined to the
locality downwind of the weapon burst point. This radiation hazard comes
from radioactive fission fragments with half-lives of seconds to a few
months, and from soil and other materials in the vicinity of the burst made
radioactive by the intense neutron flux of the fission and fusion
reactions.

It has been estimated that a weapon with a fission yield of 1 million tons
TNT equivalent power (1 megaton) exploded at ground level in a 15
miles-per-hour wind would produce fallout in an ellipse extending hundreds
of miles downwind from the burst point. At a distance of 20-25 miles
downwind, a lethal radiation dose (600 rads) would be accumulated by a