The following are the main conclusions which were reached after
thorough examination of the effects of the bombs dropped on Hiroshima
and Nagasaki:
1. No harmful amounts of persistent radioactivity were present after
the explosions as determined by:
A. Measurements of the intensity of radioactivity at the time of the
investigation; and
B. Failure to find any clinical evidence of persons harmed by
persistent radioactivity.
The effects of the atomic bombs on human beings were of three main
types:
A. Burns, remarkable for (1) the great ground area over which they
were inflicted and (2) the prevalence of "flash" burns caused by the
instantaneous heat radiation.
B. Mechanical injuries, also remarkable for the wide area in which
suffered.
C. Effects resulting from penetrating gamma radiation. The effects
from radiation were due to instantaneous discharge of radiation at the
moment of explosion and not to persistent radioactivity (of either
fission products or other substances whose radioactivity might have
been induced by proximity to the explosions).
The effects of the atomic bombs on structures and installations were of
two types: