Chromosome aberrations, micronucleus frequency, and catalase concentration in a population chronically exposed to high levels of radon

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).

Keywords:

• Antioxidant
• catalase
• cytogenetic
• micronucleus
• Mamuju
• radon

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

This work was supported by the Environmental Radioactivity Research Network Center (ERAN) [grant number I-21-14] and University of Tsukuba and the National Nuclear Energy Agency of Indonesia (Badan Tenaga Nuklir Nasional) with contract number 080.01.06 3447.001001.052.A and conducted as a BATAN Annual Research Project in 2019.

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.