Health Risks of Ionizing Radiation: - Clark University

44 Atomic Bomb Survivors
Figure 4-2. A view of the destruction of the city of Hiroshima.
The building in the top right corner still stands as a
monument to the event (www.ww2guide.com/atombomb.
shtml).
sub-samples of the Master Sample include a sample
of those survivors who were exposed in utero and
a cohort of the first generation children born to
survivors. The RERF has released the results of its
LSS studies in a series of papers that describe cancer
and noncancer mortality, solid cancer incidence, and
leukemia incidence. These documents have provided
important insights into the effects of radiation
exposure and have been updated and expanded over
time 1 .
Over the years RERF researchers have
consistently demonstrated associations between
radiation exposure and many diseases, cancer
and non-cancer. Thompson et al. (1994) found
significant excesses of total solid tumors and
tumors of the digestive system, stomach, colon,
liver, respiratory system, trachea, bronchus, lung,
skin (nonmelanoma), breast, ovary, kidney, urinary
bladder, and thyroid. Preston et al. (1994) found
positive correlations between radiation exposure and
the incidence of non-solid cancers including acute
lymphocytic leukemia (ALL), acute myelogenous
leukemia (AML), chronic myelocytic leukemia
(CML) and lymphoma in males. Shimizu et al. (1999)
demonstrated excess mortality from noncancer
diseases of the circulatory, respiratory, and digestive
systems. Other studies have demonstrated increased
risk in people who were in utero at the time of the
bombings and have examined, with inconclusive
results, risks in the F 1 generation (children born to
survivors).
Much more information is available at the
RERF website 2 including periodic updates on the
latest developments in the research project.
Doses. Reliable estimates of exposure are
critical in accurately assessing the risks associated
with the atomic bombs. When the bombs were first
dropped in 1945 the immediate effects of the bombs
were expected but the lasting effects were unknown;
at the time of the bombing there was no system of
measuring doses in place. It wasn’t until excess
leukemia became apparent a few years later that
particular attention was paid to estimating doses.
During the 1950s and 1960s Japanese scientists
created the T57D and then T65D dosimetry
systems. Gamma and neutron doses were inferred
for these dosimetry systems from calculations and
experiments performed at the Nevada Test Site.
Neutron doses were not considered to be of great
importance in these initial systems. In 1986 the
DS86 dosimetry system was developed as part of an
international effort to refine dose estimates. In the
new system there was a considerable reduction in
the estimated neutron doses; it was concluded that
neutrons were much less significant than gamma
radiation in contributing to health effects. The
DS86 system also takes into account the survivor
distance from the epicenter, shielding (both by
housing and by the posture of the person at the time
Figure 4-3. A view from the air of the bombing of Nagasaki
(http://www.astrosurf.com/lombry/quantique-bombesatomiques-pic.htm).
1 As of January 1998, 48% of the exposed cohort was still alive; follow-up will be incomplete and ongoing into the
near future.
2 www.rerf.or.jp/eigo/experhp/rerfhome.htm