Health Risks of Ionizing Radiation: - Clark University

136 Nuclear Power Accidents
average fallout dose for each country (Hoffmann
2002) and was roughly compatible with the in utero
exposure results from Greece and Germany. In all
of these cases the doses received by the developing
fetuses were low (less than 1 mSv; Michaelis et al.
1997, Hoffmann et al 2002).
Noshchenko et al. have published two papers that
describe a link between Chernobyl and leukemia in
the Ukraine. The first paper (2001) found an increase
in all leukemias, and in lymphocytic leukemias
specifically, when comparing the Zhitomir (exposed)
and the Poltava (unexposed) regions of the Ukraine.
The exposed and unexposed groups in this study
were comprised exclusively of the 1986 birth cohort
in order to focus on effects of exposure in utero.
The second paper by Noshchenko et al. (2002)
reports on a case-control study based in Zhitomir
and Rivno regions. 272 cases of leukemia were
identified in people that had been age 0-20 at the
time of the accident (72 more cases than predicted
based on pre-accident leukemia rates). Bone marrow
doses were estimated for these cases and for controls
matched by age, gender, and type of settlement.
Increased risks of leukemia generally, and acute,
acute lymphocytic, and acute myeloid leukemias
specifically, were observed for males and for both
genders combined. The authors found their risk
estimates to be similar to the estimates of Stevens
et al (1990) with residents downwind of the Nevada
Test Site 12 . There was also a distinct age effect in
this study with the earlier ages at exposure showing
a higher risk.
11.2.5 Non-cancer effects in children
When Schwenn and Brill wrote their review in
1997, it appeared that the increase in thyroid cancer
was the only significant health effect of the accident.
Since that time, a few new findings have suggested
that other health effects have developed. One
effect is thyroid autoimmune disease, a condition
where the immune system attacks the thyroid. An
associated condition is an underactive thyroid
(hypothyroidism). Pacini et al (1998) looked at 287
children from the village of Hoiniki who were up to
10 years old when they were exposed to radiation
from the Chernobyl accident (13 children were in
utero at the time of the accident). When compared
to a control group from a less-exposed province a
significant elevation of circulating thyroid antibodies
was found. This is thought to indicate a higher
probability of disease development, although at the
time of the study disease rates were similar. A study
of 53 Ukrainian children found elevated levels of
thyroid-stimulating hormone (TSH), a sign that the
pituitary gland is stimulating the thyroid in response
to underactivity (Vykhovanets et al. 1997). Elevated
TSH was also found in girls from Belarus, Russia
and Ukraine who had moved to Israel (Quastel et
al. 1997). Goldsmith et al. (1999) studied 160,000
children from Belarus, Russia and Ukraine who
were exposed to Chernobyl fallout before age 10.
These authors defined hypothyroidism by elevated
TSH and reduced thyroid hormone (thyroxin) and
compared hypothyroid incidence to individual body
burdens of cesium-137 (Cs-137), a rough proxy for
thyroid I-131 dose. They found that hypothyroidism
(148 cases) was correlated with Cs-137 although the
correlation was only significant for boys.
Radiation can cause mutations in sperm or egg
cells, also called germ cells, and these mutations can
be passed on to children as ‘germline mutations’.
Exposure of parents prior to the conception of a
child can therefore lead to effects in the children.
This is discussed briefly above in relation to
Chernobyl cleanup workers and in our chapter on
preconceptional exposure (appendix C). Studies
of families living downwind of Chernobyl have
demonstrated that germline mutations did occur as
a result of the accident although it is not clear what
the health implications of these mutations might
be. Dubrova et al. (1996) collected blood samples
from 79 families in Belarus and 105 families in the
U.K. (controls) and looked for genetic mutations in
children born in 1994. If the particular mutation was
not present in either parent then it was assumed to
have been a germline mutation. In this study the rate
of germline mutation in Belarus was twice as high
as in the U.K. Furthermore, the rate of mutation in
parts of Belarus with high cesium deposition was 1.5
12 Noshchenko et al found an odds ratio for acute lymphocytic leukemia of 3.1 (1.5-6.4) when comparing bone marrow
doses >10 mSv to doses