Ionizing Radiation and Human Health: Reviewing Models of Exposure and Mechanisms of Cellular Damage. An Epigenetic Perspective

Abstract

We reviewed available evidence in medical literature concerning experimental models of exposure to ionizing radiations (IR) and their mechanisms of producing damages on living organisms. The traditional model is based on the theory of “stochastic breakage” of one or both strands of the DNA double helix. According to this model, high doses may cause the breaks, potentially lethal to the cell by damaging both DNA strands, while low doses of IR would cause essentially single strands breaks, easily repairable, resulting in no permanent damages. The available evidence makes this classical model increasingly less acceptable, because the exposure to low doses of IR seems to have carcinogenic effects, even after years or decades, both in the exposed individuals and in subsequent generations. In addition, the cells that survived the exposure to low doses, despite being apparently normal, accumulate damages that become evident in their progeny, such as nonclonal chromosomal aberrations, which can be found even in cells not directly irradiated due to the exchange of molecular signals and complex tissue reactions involving neighboring or distant cells. For all these reasons, a paradigm shift is needed, based on evidence and epigenetics.

Long INterspersed element‐1 mobility as a sensor of environmental stresses

“…The molecular mechanisms underlying the biological effects of IR have long been studied and increasing evidence (Eden et al ., ; Huang et al ., ; Horemans et al ., ) suggests that the traditional paradigm (the breakage of one or both strands of the DNA double helix induced only by high dose exposures) should be changed toward an epigenetic model, which could also explain the risks linked to persistent exposures to small doses of ionizing radiations, as reported by Chernobyl studies (Burgio et al ., ). Following this stream of thought, it has been proposed that also the effect on L1‐RTP induced by IR could be mediated by epigenetic mechanisms.…”

Harmful Effects of Ionizing Radiation

“…Similarly, X-rays are typically used to provide static images of body parts (such as teeth and bones), and are also used in industry to find defects in welds. But, ionizing radiations can be potentially harmful if not used correctly as these also include Alpha Particles, Beta Particles, Gamma Rays and X-Rays and Neutrons: which are emitted from naturally occurring radioactive materials (such as uranium, thorium, and radium) and other man-made radioactive elements and thus, need to be handled with utmost care (1)(2)(3)(4)(5)(6)(7)(8) .…”

“…It is recommended to pregnant women to avoid exposure to radiation as much as possible. The diseases associated with radiation are as follows (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) :…”

Background ionizing radiation and semen parameters of men with reproductive problems

“…The biological consequences derive from the radiation conditions, such as the strength of the dose, way of fractioning, mass and type of tissues exposed to radiation, as well as their oxygenation. The effects of the exposure to radioactivity depends also on the individual biological characteristics of a body [5][6][7][8].…”

“…According to one theory, even small doses of radioactive radiation can have a beneficial effect on the functioning of living organisms. This phenomenon has been described as the hormetic effect [7,[9][10][11]. Undoubtedly, large doses of radiation have a negative impact on the physiology of the body.…”