Overview of Biological, Epidemiological, and Clinical Evidence of Radiation Hormesis

Abstract

The effects of low-dose radiation are being increasingly investigated in biological, epidemiological, and clinical studies. Many recent studies have indicated the beneficial effects of low doses of radiation, whereas some studies have suggested harmful effects even at low doses. This review article introduces various studies reporting both the beneficial and harmful effects of low-dose radiation, with a critique on the extent to which respective studies are reliable. Epidemiological studies are inherently associated with large biases, and it should be evaluated whether the observed differences are due to radiation or other confounding factors. On the other hand, well-controlled laboratory studies may be more appropriate to evaluate the effects of low-dose radiation. Since the number of such laboratory studies is steadily increasing, it will be concluded in the near future whether low-dose radiation is harmful or beneficial and whether the linear-no-threshold (LNT) theory is appropriate. Many recent biological studies have suggested the induction of biopositive responses such as increases in immunity and antioxidants by low-dose radiation. Based on recent as well as classical studies, the LNT theory may be out of date, and low-dose radiation may have beneficial effects depending on the conditions; otherwise, it may have no effects.

Color Doppler Evaluation of Isovolumetric Relaxation Time and of Signals Arising from Axons of the Median Nerve as a Means to Evaluate Mitochondrial Functionality in the Context of Immunotherapy of Cancer and Chronic Conditions Associated with Mitochondrial Dysfunction

“…Hormesis, by favoring the evolutionary selection of more efficient electron transport chains in mitochondria would then prevent and/or counteract mitochondrial dysfunction with associated excessive ROS production. Such a concept of hormesis in the context of radiations and cancer is well documented (Luckey, 2008;Shibamoto and Nakamura, 2018) and it can be hypothesized that the effects observed in a recent study on multiple myeloma can be ascribed to phenomena of hormesis leading to enhanced mitochondrial efficiency possibly through enhancement of coherent states at quantum level (Antonucci et al, 2019b). Whatever the case, the procedures described above represent a rapid and simple method to study mitochondrial functionality at the macroscopic and possibly at the quantum level, with a number of practical applications.…”

Manifestations of allostatic load in residents of radiation contaminated areas aged 18–24 years

“…In epidemiological studies related to the radiation exposure of the population, certain results are considered to be consequences of concomitant factors and certain biased views (Shibamoto & Nakamura, 2018). Some authors suggest that the risk of harm to the body from chronic small-dose irradiation (from 0.001 to 0.30 Gy) caused by the contamination of the territory due to the Chornobyl accident is hyperbolized, and further, that the fear of possible consequences, creates more health problems, than the radiation itself.…”

Biological Effects of Continuous Low-Dose-Rate Irradiation in Silkworms and Mice: Growth Promotion and Tumor Transplantability

“…This phenomenon of delay in tumor appearance has been observed in other studies, 9 , 10 and would imply a manifestation of stimulation of immune responses. Some molecular level evidences for such low-dose effects have been reported 17 – 22 ; low-dose radiation was found to stimulate cell proliferation via the activation of the mitogen-activated protein kinase (MAPK) pathway, 17 – 19 and p53 mutation was found to be involved in low-dose radiation-induced hormesis, adaptive response, radioresistance and genomic instability. 20 , 21 These mechanisms are related to each other and might cause an immunological response.…”

“…If we succeed in clarifying the conditions for observing growth promotion and for reducing tumor transplantability in mice, we plan to examine the immunological parameters of the mice, since the stimulatory effects of low-dose radiation on the immune system have been reported. 22 …”