One of the first, and possibly only, etiologic epidemiologic investigations conducted to date(Abylkassimova et al., 2000) was a nested case-control study of leukemia within a cohort of10,000 exposed subjects under continued follow-up (Gusev et al., 1998). Subjects wereUCRL-JC-143920 Radionuclide Contamination at Kazakhstan’s Semipalatinsk Test Site: June 2001Implications on Human and Ecological Health6/01 ERD-Kazakhstan:hkb 5comprised of 22 leukemia cases (except chronic lymphocytic leukemia) and 132 age- andgender-matched controls. Results suggest nearly a two-fold risk of leukemia (OR=1.91, 95%CI0.38-9.67) among those with doses >2 Sv compared with those having doses <0.5 Sv. Theauthors concluded that results could be biased by chance findings due to the low number of casesstudied. A descriptive study (Zhumadilov et al, 2000) reported the frequency distribution ofthyroid abnormalities among 7,271 patients (10.5% male, 89.5% female) from the Semipalatinsk(N=1,683), Ust-Kamenogorsk (N=2,032), and Pavlodar (N=1,142) regions. From 1982-96 therewas an increase in Hashimoto's thyroiditis and thyroid cancer compared with before 1982 whenmore testing occurred. Papillary cancer (48.1%) and follicular (33.1%) predominated in theSemipalatinsk region. During 1987-96, there was an increase in the number of cases amongpatients less than 40 years of age, with the highest proportion below age 20 in Semipalatinsk andUst-Kamenogorsk. A significant cancer-period interaction and increasing trend in the proportion
of cancers out of the total abnormal cases was identified. The authors recommended that
analytic etiologic studies of thyroid disease be conducted among populations exposed to
radionuclides from the STS.
The majority of the scientists and researchers we encountered during the visit agreed that the
currently observed health effects are a result of exposure during the period of testing, and not a
consequence of exposure to residual radioactivity. This is not surprising, given the
predominance of short-lived radionuclides in the atmospheric tests. About 64% of the dose
received by the near-by populace as a result of fallout occurred during the first week, and about
85% during the first three months after the explosion (Gusev et al. 1997). The current dosimetry
data reviewed above, as well as the existing residual environmental activity present in the
villages (discussed below), tend to support this claim. However, some Kazakh scientists are of
the opinion that residual radioactivity is not responsible for ongoing health impacts. The most
notable scientist expressing this view is Prof. Saim Balmukhanov, the prominent director of the
Institute of Oncology. During our meetings with Prof. Balmukhanov, he presented data collected
on the populations of the villages of Sarzhal, Kainar (both exposed) and Kokpecty (an unexposed
control group) through 1999 on pathologies other than cancer. Pathologies in cohorts born after
the atmospheric tests appeared to be significantly higher in the villages within the fallout isolines
compared to the control village. Prof. Balmukhanov made a particular case that various
pathways of exposure to plutonium particles from the soil may be a causative agent in these
pathologies (such as alpha particles causing skin damage, or plutonium accumulation in the
bones of horses, and subsequent consumption of food dishes made from horse bones). While it
was not possible to determine if standard epidemiological techniques were used in Prof.
Balmukhanov’s work, he raised interesting questions which may merit further examination
(Balmukhanov, 1999). There is little doubt that people living in the STS region suffer from a
range of adverse health effects, including high rates of infectious and noninfectious diseases,
cancer, and hematological disorders. However the task of definitively relating any of these
effects to nuclear weapons testing will be complicated by numerous confounding factors such as
inadequate nutrition, poor water quality, and unsanitary living conditions (Logachev et al.,
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