important tasks assigned to the mission

One of the most important tasks assigned to the mission
which investigated the effects of the bombing was that of
determining if the radiation effects were all due to the instantaneous
discharges at the time of the explosion, or if
people were being harmed in addition from persistent radioactivity.
This question was investigated from two points
of view. Direct measurements of persistent radioactivity
were made at the time of the investigation. From these
measurements, calculations were made of the graded radiation
dosages, i.e., the total amount of radiation which
could have been absorbed by any person. These calculations
showed that the highest dosage which would have
been received from persistent radioactivity at Hiroshima
was between 6 and 25 roentgens of gamma radiation; the
highest in the Nagasaki Area was between 30 and 110 roentgens
of gamma radiation. The latter figure does not refer
to the city itself, but to a localized area in the Nishiyama
District. In interpreting these findings it must be understood
that to get these dosages, one would have had to
remain at the point of highest radioactivity for 6 weeks
continuously, from the first hour after the bombing. It is
apparent therefore that insofar as could be determined at
Hiroshima and Nagasaki, the residual radiation alone could
not have been detrimental to the health of persons entering
and living in the bombed areas after the explosion.
The second approach to this question was to determine
if any persons not in the city at the time of the explosion,
but coming in immediately afterwards exhibited any symptoms
or findings which might have been due to persistence
induced radioactivity. By the time of the arrival of the Manhattan
Engineer District group, several Japanese studies
had been done on such persons. None of the persons examined
in any of these studies showed any symptoms which
could be attributed to radiation, and their actual blood cell
counts were consistently within the normal range. Throughout
the period of the Manhattan Engineer District investigation,
Japanese doctors and patients were repeatedly requested
to bring to them any patients who they thought
might be examples of persons harmed from persistent radioactivity.
No such subjects were found.
It was concluded therefore as a result of these findings
and lack of findings, that although a measurable quantity
of induced radioactivity was found, it had not been sufficient
to cause any harm to persons living in the two cities
after the bombings.