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Global Translational Medicine Low-dose radiation

and females underwent internal alpha-irradiation are generally compatible with hormesis, that is, favorable
from incorporated plutonium of total absorbed effects within a certain low-dose range, possibly except
radiation dose in liver over 0.025 Gy.” 30 in genetically modified cancer-prone animals. In some
“There was a significantly increasing trend (ERR/Gy) experimental and epidemiological studies, low doses
of the IHD mortality with the total absorbed dose to turned out to be protective against cardiovascular diseases.
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liver from internal alpha-radiation due to incorporated Existing evidence in favor of hormesis is considerable. 76-80
plutonium.” 28 This implies that epidemiological data partly disagree
“The incidence data point to higher risk estimates (in with the experiments. The cause thereof may be bias in
MPA workers) compared to those from the Japanese some epidemiological research on low-dose exposures to
A-bomb survivors.” 29 ionizing radiation, that is, inter-study differences in quality
“The categorical analyses showed that CeVD and reliability. 1,81
incidence was significantly higher among workers
with total absorbed external gamma-ray doses >0.1 Gy In humans who received radiotherapy, myocardial
[emphasis added] compared to those exposed to lower fibrosis developed at doses ≥30 Gy. An increased risk
doses and that CeVD incidence was also significantly of coronary disease following radiotherapy has been
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higher among workers with total absorbed internal registered after exposures to 7.6 – 18.4 Gy, which is
alpha-particle doses to the liver from incorporated still much higher than the mean doses in the cohorts
plutonium >0.01 Gy compared to those exposed to discussed above. Unrealistic cardiovascular risks at low-
lower doses.” 49 dose exposures call into question the cancer risks reported
by the same researchers. Finally, the quality of dose
The risk estimates by Azizova et al. were significantly estimation is crucial for studies of radiation risks. Recall
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higher than those in other studies. In the MPA cohort, the bias should be mentioned in this connection: patients with
70
incidence of circulatory diseases was reported to be higher cancer and individuals with other diseases tend to recollect
in members who received gamma-ray doses of >0.1 Gy all circumstances related to radiation better than healthy
than in people exposed to lower doses. 49,50 Cause–effect controls. 82
relationships are improbable at such a low dose, taking into
account the dose comparisons below. The United Nations Summarizing the above and previously published
1,2
Scientific Committee on the Effects of Atomic Radiation arguments, the detrimental effects of anthropogenic
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(UNSCEAR 2006) could not conclude causality between radiation would approach zero as the dose rate decreases
exposures below 1 – 2 Gy and cardiovascular diseases. to levels comparable to natural background radiation.
The level 1 – 2 Gy is an underestimation resulting from Moreover, the dose–effect relationship may exhibit an
the screening effect, selection, self-selection, other biases, inverse correlation within a certain range, consistent
and confounding factors in epidemiological studies. with the convey of hormesis. Obviously, hormesis cannot
Approximately 10 years ago, during the author’s visit at the be used in radiation safety regulations if consistent
Medical Radiological Research Center in Obninsk, Russia, experimental evidence has not been obtained in large-
Victor Ivanov emphasized his leading role in the UNSCEAR scale animal experiments using different species. Even
Reports. Political and economic interests sometimes thereafter, precautions would be necessary as hormetic
overweigh scientific objectivity, which is perceivable stimuli may act without a threshold on pre-damaged
from certain documents issued by esteemed international or atrophic tissues or synergistically with known or
organizations such as UNSCEAR. As mentioned above, unknown noxious agents. DNA damage and repair are
the Chernobyl accident has been exploited to strangulate normally in a dynamic equilibrium. Accordingly, there
the worldwide development of the atomic industry. At may be an optimal exposure level, as it is for many other
3
present, there are no alternatives to nuclear power; in the environmental agents, such as visible and ultraviolet
long run, non-renewable fossil fuels will probably become light, various chemical elements and compounds, as well
increasingly expensive, contributing to uncontrolled as products of water radiolysis. Moreover, evolutionary
83
population growth in oil-producing countries and poverty adaptation to a changing environmental factor would lag
in the rest of the world. behind its current value and correspond to some average
from the past. Natural background radiation has been
7. Discussion decreasing during the time of life’s existence on Earth.
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Dose levels associated with cardiac derangements in The character of the dose–response relationship at the dose
animal experiments and humans following radiotherapy close to the natural radiation background can be predicted
have been much higher than the average doses in the based on general considerations. Many carcinogenic factors
cohorts discussed above. 72-75 Results of animal experiments exist. The lower the level of environmental radioactivity,

Volume 4 Issue 1 (2025) 61 doi: 10.36922/gtm.7229