Abstract
Purpose
To deepen our knowledge on the effects of high levels of indoor radon exposure, we assessed the frequencies of unstable and stable chromosome aberrations and micronucleus (MN), as well as the concentration of an endogenous antioxidant (catalase, CAT), in blood samples of individuals chronically exposed to high indoor radon concentrations in Indonesia (Tande-Tande sub-village, Mamuju, West Sulawesi). Moreover, we also investigated the occurrence of a radio-adaptive response (RAR) in Tande-Tande sub-village inhabitants using the G2 MN assay.
Materials and Methods
The frequencies of dicentric (DC), acentric (AF), ring (R), and translocation (Tr) chromosomes in Tande-Tande inhabitants were compared to those in people living in a reference area with low levels of indoor radon levels (Topoyo village, Indonesia). The number of MN per 1000 binucleated cells (BNC) and CAT concentration per total protein was quantified and compared between groups. Lastly, we irradiated (2 Gy) phytohemagglutinin-stimulated samples in vitro and measured the frequency of MN to verify the occurrence of a RAR in Tande-Tande sub-village inhabitants.
Results and Conclusion
The frequencies of DC, AF, and Tr did not differ between Tande-Tande inhabitants and control subjects (p = 0.350, 0.521, 0.597). The frequency of MN in Tande-Tande inhabitants was significantly lower than that in the control group (p = 0.006). Similarly, CAT concentration in Tande-Tande inhabitants was also significantly lower than that in the control population (p < 0.001). Significant negative correlations were identified for MN number and CAT concentration versus indoor radon concentration, annual effective dose, or cumulative dose both within groups and when all data were analyzed together. Our findings indicate that, despite the high indoor radon levels, Tande-Tande inhabitants are not under oxidative stress, since this group had lower CAT concentration and MN frequency than those in the control group. The negative correlation between MN frequency and indoor radon concentration, annual effective dose, and cumulative dose suggests the occurrence of an RAR phenomenon in Tande-Tande sub-village inhabitants. This interpretation is also supported by the results of the G2 MN assay, which revealed lower MN frequencies after in vitro irradiation of samples from Tande-Tande sub-village inhabitants than those in samples from the control group (p = 0.0069, for cumulative MN frequency; p = 0.0146, for radiation-induced MN only).
Acknowledgements
The authors are grateful to thank the participants of this study for their cooperation. The first author also gratefully acknowledges the SAINTEK scholarship program of the Ministry of Research, Technology and Higher Education of the Republic of Indonesia. We would also like to thank Daniel Moreira for editing and proofreading this manuscript in English.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
Notes on contributors
Dwi Ramadhani
Dwi Ramadhani is a doctoral student in the Doctoral Program for Biomedical Sciences, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia, and a researcher in the Research Center for Radioisotope, Radiopharmaceutical, and Biodosimetry Technology, Research Organization for Nuclear Energy, National Research and Innovation Agency, Indonesia.
Sofiati Purnami
Sofiati Purnami is a researcher in the Research Center for Safety, Metrology, and Nuclear Quality Technology, Research Organization for Nuclear Energy, and National Research and Innovation Agency.
Devita Tetriana
Devita Tetriana is a researcher in the Research Center for Safety, Metrology, and Nuclear Quality Technology, Research Organization for Nuclear Energy, and National Research and Innovation Agency.
Irawan Sugoro
Irawan Sugoro is a researcher in the Research Center for Radiation Process Technology, Research Organization for Nuclear Energy, and National Research and Innovation Agency.
Viria Agesti Suvifan
Viria Agesti Suvifan is a professional staff in the Research Center for Safety, Metrology, and Nuclear Quality Technology, Research Organization for Nuclear Energy, and National Research and Innovation Agency.
Nastiti Rahadjeng
Nastiti Rahadjeng is a radiation oncologist in the Research Center for Safety, Metrology, and Nuclear Quality Technology, Research Organization for Nuclear Energy, and National Research and Innovation Agency.
Septelia Inawati Wanandi
Septelia Inawati Wanandi is a professor in the Department of Biochemistry & Molecular Biology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia.
Heri Wibowo
Heri Wibowo is a lecturer in the Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia.
Ikuo Kashiwakura
Ikuo Kashiwakura is a professor in the Graduate School of Health Sciences, Hirosaki University, Hirosaki, Japan.
Tomisato Miura
Tomisato Miura is a professor at the Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki, Japan.
Mukh Syaifudin
Mukh Syaifudin is a research professor in the Research Center for Radioisotope, Radiopharmaceutical, and Biodosimetry Technology, Research Organization for Nuclear Energy, National Research and Innovation Agency, Indonesia.