Health Risks of Ionizing Radiation: - Clark University

times higher than in less-contaminated areas. This
paper was widely challenged on the grounds that the
control group (British families) was too different
from the experimental group, that several potentially
confounding factors were not accounted for, and
that the A-bomb survivor research was not detecting
a genetic effect. Schwenn and Brill described the
Dubrova results as “highly suspect”. In 2002,
however, Dubrova et al. published new results that
confirm the earlier findings. A study of 256 Ukrainian
families, using Ukrainian children born before the
Chernobyl accident as controls, found a 1.6-fold
increase in germline mutations (Dubrova et al.
2002a). The mutations only appeared in the paternal
germlines. These researchers also investigated
germline mutations around the Semipalatinsk
nuclear test site in Kazakhstan, and again found a
similar increase of 1.8-fold over controls (Dubrova
et al. 2002b). In this study Dubrova et al. were also
able to detect a smaller increase in mutations in the
next generation.
Effects on the development of children who
were exposed in utero, and mental health effects in
particular, have also been studied. Although children
from contaminated area tend to show some negative
impacts on IQ or mental and behavioral function, it
becomes very hard to disentangle effects of radiation
from effects of family stress associated with
evacuation, resettlement, and anxiety concerning
the accident (Kolominsky et al. 1999, Igumnov and
Drozdovitch 2000).
11.2.6 Chernobyl discussion
In summary, researchers have detected increased
cancer, increased cardiovascular disease and
Nuclear Power Accidents 137
impaired immune systems in emergency and cleanup
workers. A dramatic increase in childhood thyroid
cancer has been seen among Chernobyl downwinders
in addition to evidence of an increase in childhood
leukemia, an increase in thyroid autoimmune
disease, effects on mental health in children exposed
in utero, and an increase in germline mutations in
the children of exposed parents. The thyroid cancer
excess was larger than expected based on old thyroid
cancer risk models (Buglova et al. 1996). Newer
models based on childhood medical exposures to
external radiation are closer to the observed excess
around Chernobyl. Remaining differences between
observed and expected cancer rates might be partially
attributable differences in dietary iodine (although
there is still insufficient data for anything more
than speculation on this point) and to differences in
follow-up time of exposed children. The dramatic
effect of age at exposure is clear in the Chernobyl
downwinders as it is in medically exposed children.
Of roughly 800 childhood cancer cases in the heavily
contaminated areas around Chernobyl, 98% were
in children under age 10 and 65% were in children
under age 5. Childhood leukemia rates measured
by Noshchencko et al. (2002) are compatible with
the estimated leukemia effects of nuclear weapons
testing in Nevada. The suggestive evidence of
infant leukemia following in utero exposure in
Europe involves very low doses in the range of
background radiation. Germline mutation results for
Chernobyl have been replicated around the test site
in Semipalatinsk and demonstrate that the children
of exposed parents have been affected in some way
(Dubrova 2003).