Lung damage by thoron progenies versus possible damage redemption by lung stem cells: a perspective

Abstract

Purpose

Natural radiation is the major source of human exposure to ionizing radiation. About 52% of the total dose received from the high natural background radiations (HNBR) areas are due to inhalation dose from radon (²²²Rn)/thoron (²²⁰Rn) and their progenies. Hence, we reviewed the biological effects of ²²²Rn/²²⁰Rn and their progenies on lung tissue, and the possible role of lung stem cells in salvaging the damage caused by ²²²Rn/²²⁰Rn and their progenies.

Materials and Method

We have extensively reviewed articles among several hits obtained in PubMed, Scopus, and Elsevier databases with keywords ‘Radon/Thoron’ OR Thoron progeny/Radon progeny OR ‘Thoron/Radon inhalation and lungs’, and proceed for further analysis. Also, databases related to oxidative damage to lung stem cells by radiation and the repair mechanisms involved by the lung stem cells were also included.

Results

Based on the existing epidemiological data on radon in residential buildings, we found that evidence exists on the association of radon induced lung carcinogenesis, but the data regarding the role of thoron induced lung damage is very limited and inconclusive. We also found that limited information has been provided based on ecological designs, leading to poor documentation of health statistics, in particular, organ-specific cancer rates. Finally, we tried to elucidate the possible mechanisms of lung injury induced by thoron inhalation and the probable role of lung stem cell toward the redemption of such oxidative damages.

Conclusion

Existing epidemiological data on thoron inhalation and associated health outcomes are limited and inconclusive. Further, in vivo experiments, with respect to radon/thoron inhalation dose rate ranges corresponding to the HNBR areas will be helpful in understanding the cellular and molecular effects.

Keywords:

• Thoron
• ionizing radiation
• lung stem cells
• oxidative damage
• repair mechanisms

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Acknowledgment

The authors thank the Stem Cells and Regenerative Medicine Centre of Yenepoya Research Centre/Yenepoya (Deemed to be University) for providing the online library resources for writing this review article.

Author contributions

DC carried out the extensive literature review and writing the manuscript. US contributed to the writing and artwork of the manuscript. NNB provided detailed inputs regarding radon and thoron, their physical properties and possible biological effects and contributed to the formulation and reviewing of the manuscript. BKS provided detailed inputs regarding the physical properties of radon and thoron, formulation and reviewing of the manuscript. SSP contributed the formulation and reviewing and approving of the manuscript. BB conceptualized the outline and flow of the manuscript, wrote, reviewed, and approved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors express thanks to Board of Research in Nuclear Sciences, Department of Atomic Energy, Government of India for sanctioning a Research Project on this subject with grant no. 36(4)/14/51/2016. No funding was utilized for preparing this manuscript.

Notes on contributors

Debajit Chaudhury

Debajit Chaudhury is exploring his PhD in the Stem Cells and Regenerative Medicine Center, Yenepoya Research Center, at Yenepoya (deemed to be University), Mangalore, under the co-guidance of Drs. Sudheer Shenoy P and Bipasha Bose. He has a Master's degree in Medical Biochemistry. His research areas are Radiation Biology, Lung Stem Cell Biology, Molecular Biology, and Toxicology.

Utsav Sen

Utsav Sen is a Senior Research Fellow exploring his PhD, funded by the Indian Council of Medical Research (ICMR) for his PhD work in the Stem Cells and Regenerative Medicine Center, Yenepoya Research Center, at Yenepoya (deemed to be University), Mangalore, under the co-guidance of Drs. Bipasha Bose and Sudheer Shenoy P. He has a Master's degree in Biotechnology. His research areas are Regenerative and Cancer Stem Cell Biology.

Nagesh N. Bhat

Nagesh N. Bhat currently works at the Radiological Physics & Advisory Division, Bhabha Atomic Research Center. His research includes Biodosimetry, Radiation biology, charged particle radiation biology, instrumentation and automation of facilities for radiation biology studies.

Bijay Kumar Sahoo

Bijay Kumar Sahoo currently works at the Radiological Physics & Advisory Division, Bhabha Atomic Research Center. His research involves instrumentation of radon and thoron, modeling radon, thoron transport in porous media, application in earthquake precursory study, uranium and thorium mining and milling industries, uranium and thorium geo exploration and occupational and ambient dosimetry.

Sudheer Shenoy P

Sudheer Shenoy P is an Associate Professor in of Stem cells and Regenerative Medicine Center, Yenepoya Research Center, at Yenepoya (Deemed to be University), Mangalore. His research program focuses on Regenerative and Cancer Stem Cells, Muscle Stem Cells. He holds a PhD degree in Biochemistry with 14 years of post-PhD research experience.

Bipasha Bose

Bipasha Bose is an Associate Professor at the Stem cells and Regenerative Medicine Center, Yenepoya Research Center, at Yenepoya (Deemed to be University), Mangalore. Her current research program focuses on radiation biology, Regenerative and Cancer Stem Cell biology. She holds a PhD in Applied Biology-Molecular Carcinogenesis and has 17 years of post-PhD research experience.