Radiation Hormesis: Historical and Current Perspectives

Baldwin, Jonathan; Grantham, Vesper

doi:10.2967/jnmt.115.166074

Cited by 62 publications

(62 citation statements)

References 20 publications

(37 reference statements)

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“…Similar to the previous studies (Alexandrova et al, 2011;Rozhko at al., 2007), nonlinearity of bioluminescence response to 241 Am is evident from Fig.2; three stages of bioluminescence kinetics are observed: (1) absence of effect (stress recognition), (2) bioluminescence activation (adaptive response), and (3) suppression of the bioluminescence function of the bacteria (toxic effect). Similar responses of organisms to external exposures are usually attributed to the hormesis phenomenon (Kudryasheva and Rozhko, 2015;Burlakova et al, 2004;Calabrese, 2014;Baldwin and Grantham, 2015;Shi et al, 2016).…”

Section: Resultsmentioning

confidence: 64%

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Is bacterial luminescence response to low-dose radiation associated with mutagenicity?

Rozhko

Guseynov

Guseynova

et al. 2017

Journal of Environmental Radioactivity

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Luminous marine bacteria are widely used as a bioassay with luminescence intensity being a physiological parameter tested. The purpose of the study was to determine whether bacterial genetic alteration is responsible for bioluminescence kinetics change under low-dose radiation exposure. Alpha-emitting radionuclide 241Am and betaemitting radionuclide 3H were used as sources of low-dose ionizing radiation. Changes of bioluminescence kinetics of Photobacterium Phosphoreum in solutions of 241Am(NO3)3, 7 kBq/L, and tritiated water, 100 MBq/L, were studied; bioluminescence kinetics stages (absence of effect, activation, and inhibition) were determined. Bacterial suspension was sampled at different stages of the bioluminescent kinetics; the doses accumulated by the samples did not exceed 1 Gy, being close to a tentative limit of a low-dose interval. Sequence analysis of 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose alpha and beta radiation. Previous results on bacterial DNA exposed to lowdose gamma radiation (0.25 Gy) were analyzed and compared to those for alpha and beta irradiation. A conclusion was made that DNA mutations are not associated with bacterial bioluminescence activation and inhibition under the applied conditions of low-dose alpha, beta, and gamma radioactive exposure. To view all the submission files, including those not included in the PDF, click on the manuscript title on your EVISE Homepage, then click 'Download zip file'. Abbreviations:ROS -Reactive Oxygen Species HTO -tritiated water ABSTRACTLuminous marine bacteria are widely used as a bioassay with luminescence intensity being a physiological parameter tested. The purpose of the study was to determine whether bacterial genetic alteration is responsible for bioluminescence kinetics change under low-dose radiation exposure. Alpha-emitting radionuclide 241 Am and betaemitting radionuclide 3 H were used as sources of low-dose ionizing radiation. Changes of bioluminescence kinetics of Photobacterium Phosphoreum in solutions of 241 Am(NO 3 ) 3 , 7 kBq/L, and tritiated water, 100 MBq/L, were studied; bioluminescence kinetics stages (absence of effect, activation, and inhibition) were determined. Bacterial suspension was sampled at different stages of the bioluminescent kinetics; the doses accumulated by the samples did not exceed 1Gy, being close to a tentative limit of a low-dose interval. Sequence analysis of 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose alpha and beta radiation. Previous results on bacterial DNA exposed to low-dose gamma radiation (0.25 Gy) were analyzed and compared to those for alpha and beta irradiation. A conclusion was made that DNA mutations are not associated with bacterial bioluminescence activation and inhibition under the applied conditions of low-dose alpha, beta, and gamma radioactive exposure.

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Section: Resultsmentioning

confidence: 64%

“…Three models exist describing this relationship: linear, threshold, and hormesis models (Kudryasheva and Rozhko, 2015;Burlakova et al, 2004;Calabrese, 2014;Baldwin and Grantham, 2015). The hormesis hypothesis suggests that low-dose radiation can be favorable for living organisms.…”

Section: Introductionmentioning

confidence: 99%

Is bacterial luminescence response to low-dose radiation associated with mutagenicity?

Rozhko

Guseynov

Guseynova

et al. 2017

Journal of Environmental Radioactivity

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“…On the other hand, studies showing the beneficial effects of low-dose radiation are increasing, and now over several hundred papers exist. They are reviewed in other excellent articles [1,2,4], so in the present article, we will introduce studies related to us and those in which we are particularly interested. Meanwhile, recent studies suggest that stem cells reside in the body for a long time and they may accumulate genotoxic damages derived from low-dose radiation; therefore, further investigations on stem cell biology may also be important [22,23].…”

Section: Biological Studies Of Radiation Hormesismentioning

confidence: 99%

“…On the other hand, the effects of lower-dose exposure remain controversial. Some consider radiation exposure below 200 mSv to be hazardous based on the linear-no-threshold (LNT) hypothesis, whereas others consider low-dose exposure to have beneficial effects, known as radiation hormesis and the radioadaptive response [1,2,3,4,5]. Otherwise, however, it may have no effects.…”

Section: Introductionmentioning

confidence: 99%

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

Shibamoto

Nakamura

2018

IJMS

101

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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.

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“…The topics of the threshold, hormesis and DDREF are interrelated with the linear no-threshold theory (LNT). Hormesis and LNT are considered controversial by many scientists; discussion is in [3][4][5][6][7][8]. The LNT is corroborated by the following arguments: the more tracks go through a cell nucleus, the more DNA damage would result and the higher the risk of malignant transformation would be.…”

Section: Arguments Against Linear No-threshold Theory (Lnt)mentioning

confidence: 99%

Biological Effectiveness of Ionizing Radiation: Acute vs. Protracted Exposures

2016

J Environ Stud

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This letter refers to the current discussion around re-evaluation of the dose and dose rate effectiveness factor (DDREF) equal to 2, presently recommended by the International Commission on Radiological Protection. The topics of the threshold, hormesis and DDREF are interrelated with the linear no-threshold theory (LNT). The LNT does not take into account that DNA damage and repair are permanent processes in dynamic equilibrium. Given the evolutionary prerequisite of best fitness, it would be reasonable to assume that living organisms have been adapted by the natural selection to the background levels of ionizing radiation. Accordingly, there must be an optimal exposure level, as it is for many environmental factors. Several studies cited in the literature in support of the LNT and lowering of the DDREF down to 1 are discussed here. In the author's opinion, the dose-effect relationships with non-neoplastic diseases found in certain exposed populations call in question dose-effect relationships with cancer. Self-selection and other biases in epidemiological studies are discussed. The dose-response relationships should be clarified in largescale experiments involving different animal species. In conclusion, the LNT and under-estimation of DDREF tend to exaggerate radiationrelated health risks at low radiation doses and dose rates. Arguments against Linear No-Threshold Theory (LNT)Radiation-related cancer risk estimates have been primarily based on the data from atomic bomb survivors. To adjust the risk estimates at acute exposures to low dose and continuous (low dose rate) exposures, a dose and dose rate effectiveness factor (DDREF) is used [1]. This letter refers to the discussion around re-evaluation of the DDREF value equal to 2, currently recommended by the International Commission on Radiological Protection (ICRP) [2]. The topics of the threshold, hormesis and DDREF are interrelated with the linear no-threshold theory (LNT). Hormesis and LNT are considered controversial by many scientists; discussion is in [3][4][5][6][7][8]. The LNT is corroborated by the following arguments: the more tracks go through a cell nucleus, the more DNA damage would result and the higher the risk of malignant transformation would be. "Decreasing the number of damaged cells by a factor of 10 would be expected to decrease the biological response by the same factor of 10" [9]. This concept does not take into account that DNA damage and repair are permanent processes in dynamic equilibrium. Given the evolutionary prerequisite of best fitness, it would be reasonable to assume that living organisms have been adapted by the natural selection to background levels of ionizing radiation [10]. Accordingly, there must be an optimal exposure level, as it is for many environmental factors: visible and ultraviolet light, different chemical elements and compounds [11], as well as the products from radiolysis of water [12]. Evolutionary adaptation to a changing environmental factor would lag behind its current value and correspond to some ...

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Radiation Hormesis: Historical and Current Perspectives

Cited by 62 publications

References 20 publications

Is bacterial luminescence response to low-dose radiation associated with mutagenicity?

Is bacterial luminescence response to low-dose radiation associated with mutagenicity?

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

Biological Effectiveness of Ionizing Radiation: Acute vs. Protracted Exposures

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