Problems in RERF Epidemiological Studies

Problems in RERF Epidemiological Studies

There are serious problems in the epidemiological studies of the RERF when the results
of the studies are applied to survivors. One is neglect of the contribution from the
residual radiation for the estimation of exposed dose of survivors. This originated in the
initial investigation of survivors done by the ABCC. The other serious problem is
selection of a non-irradiated control group. The epidemiological studies by the ABCCRERF
have been adopted by survivors themselves as the non-exposed control cohort for
the studies. In the recent RERF investigations the survivors who had been exposed to
less than 0.005 Sv of the DS86, and the NIC group in which the early entered survivors
are included, are used as the control group. As is shown in the preceding sections these
distant and entrant survivors were affected by the residual radiations estimated at more
than 0.5􀁤1.5 Gy on average which is several hundred times 0.005 Sv. Then it is evident
that the ABCC-RERF studies cannot be applied to the estimation of exposure for􀉹 distant

Hiroshima Male Group vs Okayama Prefectures are shown in Fig. 11 against exposure
to initial radiation. Assuming the relative mortality rates increase linearly, regression
lines are drawn for each cancer. If there is no excess of relative mortality rates the
regression curves will cross the line with relative mortality 1.0 at zero exposure point of
the initial radiation. However, the regression lines cross at negative exposure points
denoted 􀂺 marks in Fig. 11. This fact means even the survivors in the very low dose
initial radiation group were exposed to fallout radiation of 0.4 to 1.0 Sv. 􀉹
􀉹􀉹Therefore the results of the ABCC-RERF studies should not be applied to the criteria
of atomic diseases at the very least for distant and entrant survivors even though they
may be used to estimate external irradiation effects of the strong initial radiation.