Introduction
The occurrence of leukemia and malignant tumors are the most often
remote effects of radiation. It has also been shown that the health
effects of radiation might depend on the duration of the exposure [1,
2]. Damage by ionizing radiation is known to be mainly due to lipid
peroxidation caused by active oxygen forms. The higher the level of the
active oxygen form, the greater the oxidative damage [3, 4]. In the
long term, even a small dose of radiation could cause genetic changes,
oncogenesis, and physiological changes, associated with a compromised
immune system and increased cellular stress [5, 6]. In contrast, it
is also believed that a low dose of radiation could induce both positive
and negative bioeffects, thereby reducing carcinogenesis, increasing
longevity, and increasing fertility [7, 8, 9].
Absorption of energy from ionizing radiation by genetic material in the
cell is known to lead to DNA damage, which in turn leads to chromosome
aberrations and gene mutations. Both early and late effects of radiation
has been reported to lead to organ and tissue damage caused by cell
death, which in turn leads to the development of cancer. Epidemiological
studies have demonstrated a dose-response relationship for the induction
of cancer [10]. For instance, aberrations of the chromosomal complex
of peripheral blood lymphocytes were revealed in the long term following
the incidence of the leaked ionizing radiation at the Chernobyl nuclear
power plant (ChNPP) [11].
The results of this study revealed a high prevalence of chronic diseases
among the population living in the vicinity of radioactive waste storage
facilities. The population was reported to also receive chronic
irradiation as a consequence of the long term exposure to radiation,
with the results of the study pointing to an almost complete absence of
healthy people living in the area. Diseases of the cardiovascular,
hematopoietic, respiratory, and musculoskeletal systems occupied the top
places in the prevalence of diseases among the population exposed to
radiation [12, 13, 14]. According to the results obtained from field
and laboratory analytical studies, the authors identified the negative
impact of the tailings dump (radioactive waste storage) of the
Stepnogorsk mining and chemical plant (uranium mining enterprise,
Republic of Kazakhstan) on the environment of adjacent areas, expressed
as radionuclides contaminating the soil, water and vegetation. The
population living in local radioactive areas was estimated to receive an
annual effective dose of about 6.5 mSv/y, whereas the normal level from
natural sources should be 1 mSv/y [15].
Recently, much has been said about the ”untargeted effects” of ionizing
radiation in a remote period. Briefly, ”targetless effects” is
considered the ability to transfer changes from irradiated cells (target
cells for radiation exposure) to unirradiated cells. This could be
considered as one of the directions of the distant effects of ionizing
radiation. The authors also received new data related to the radiation
”witness effect” and adaptive response. It was found that there are 2
mechanisms - intercellular interactions and secret factors that could be
transmitted at a distance. The importance of studying ”non-targeted
effects” is related to the use of research results in theoretical
radiobiology, as well as in radiation ecology, when studying the
long-term consequences of human-made disasters [16, 17]. It has been
shown that ”in radiation disasters, mankind for the first time has
encountered the complex, multifactorial stress,” which includes not only
the biological effects of radiation but also the psychological stress of
a complex structure. Psychological manifestations and consequences of
this stress have been associated with the expectation of a health
catastrophe [18].
One of the most radiosensitive functions of human and animal organisms
is immunological reactivity. A characteristic feature of exposure to
radiation is known to be the long preservation of damages in separate
parts of the immune system and its associated remote consequences and
complications manifested by the development of malignant tumors
[19]. Ionizing irradiation in different doses in remote periods
might lead to the suppression of the innate and acquired humoral and
cellular immunity. Whole-body radiation exposure at doses >
2 Gy (Gray) could cause different clinical symptoms; higher doses could
be so acute that they would become life-threatening [20].
Studies on the health effects of remote exposure to ionizing radiation
are relevant worldwide, including Kazakhstan; some areas have been
exposed to local fallout from nuclear tests at the Semipalatinsk nuclear
test site; the populations living in these areas have been exposed to
internal and external exposure. People who received a specific dose of
radiation while living in these areas, might also face many other daily
difficulties, causing further emotional distress. Given the importance
of the immune system in the formation of pathological processes, its
high sensitivity, as well as the significant consequences following its
compromise, we were interested in its role in the formation of
pathological processes in combination with the action of emotional
stress and remote period exposure to ionizing radiation.