Health Risks of Ionizing Radiation: - Clark University

154 Communities Near Nuclear Facilities
caused by viruses that are transmitted more readily
in areas where new population mixing is occurring;
some of the towns near new nuclear facilities fit this
description.
These studies are further limited in many cases
by simplistic and uninformative study designs. For
example, in most studies a circle of distance is drawn
around a facility and everyone inside is assumed
to have the same potential risk 25 . Radioactive
contamination from a facility is unlikely to be
dispersed so uniformly. Soil plutonium around Rocky
Flats, for example, is distributed almost exclusively
in a south-east direction (Johnson 1981). In some
cases we can see disease patterns that suggest
nonuniform patterns of contamination. Hoffman et
al. (1997) found six cases of childhood leukemia
within 5 km of the Krummel nuclear power plant in
Germany where only 1.3 cases were expected. All
six cases occurred on the south bank of the Elbe,
which cut the study area in half (Krummel is on the
north bank). This may have occurred by chance, but
only 20% of the population in the study area lived on
the south side. If it were the case that contamination
from Krummel only affected the south side of the
river then we would want to calculate the risk for
that area: the SIR for the whole 5-km radius was 4.6
(2.1-10.3) while considering only the south half of
the circle gives an estimate of 24.0 (10.8-53.4).
Although the studies are limited in many ways
there is still a great deal of information that we
can try to interpret. Although we have little or no
dose information we do have information on some
important differences in endpoints. Studies of adults
and children have produced different results, and
this is not surprising considering what we know
about the unique sensitivity of children. We can
also differentiate between studies of mortality and
studies of incidence, or between studies of different
types of nuclear facility.
The highest exposures considered in this section
were experienced by Techa River residents near the
Mayak facility in Russia. Studies of this community
have shown a significantly positive leukemia risk at
doses as low as 0.18 Gy bone marrow dose (RR 2.0;
1.3-3.1) and a significantly positive solid cancer risk
at 0.04 Gy soft-tissue dose (RR 1.2; 1.1-1.3).
Studies of adults (or all ages combined) at lower
doses have had variable results (Table 12-1). Studies
of Oak Ridge and Rocky Flats, both weapons plants,
have produced evidence of increased local cancer
risks attributable to the plants (Mangano 1994,
Johnson 1981, Crump 1987). These facilities have
had unique operating histories with greater potential
for radioactive releases than commercial nuclear
sites. Most studies of commercial facilities have
not detected a significant excess of adult cancer
and no individual cancer site stands out from these
analyses as a unique high-risk endpoint. Based
on studies of nuclear workers we might have an a
priori interest in myeloma among adults. Dousset
(1989) found 3 cases (1.1 expected) within 10
km of La Hague and Lopez-Abente et al. (1999)
found relative risks of 1.62 (0.73-3.58) and 1.13
(0.70-1.85) around Spanish power plants and fuel
facilities, respectively. Boice et al. (2003b) found
an increased myeloma incidence around the Apollo
and Parks facilities in Pennsylvania (SIR 1.91; 0.95-
3.42). Forman et al. (1987), on the other hand, found
that myeloma mortality was significantly less than
expected around nuclear sites in England and Wales.
Since no consistent patterns emerge from studies of
commercial facilities we can conclude that any real
risks are presumably low and masked by the variety
of background rates and study designs.
Childhood cancer, on the other hand, and
childhood leukemia in particular, appear to be
consistently associated with nuclear facilities.
This is most apparent in studies of leukemia (and
lymphoma) incidence (Table 12-2). Each site has
had a unique history of radioactive releases, each
study design is different from the next, and each
study area has a unique pattern of background
cancer; for these reasons we should not expect risk
estimates to be of a similar value. That said, looking
at Table 12-2 we see that most studies of childhood
leukemia around nuclear facilities have found a
significant or nearly significant excess; an ‘average’
excess would be two-fold or less. There is not much
25 There were some exceptions in this section. Gadekar and Gadekar (1994), Mangano (1994), Mangano et al. (2002)
and Morris and Knorr (1996) all took weather patterns into account to some degree and Johnson (1981) and Crump
et al. (1987) made use of soil plutonium measurements.