Journal of Radiation Protection and Research

  • 제48권2호
  • /
  • Pages.59-67
  • /
  • 2023
  • /
  • 2508-1888(pISSN)
  • /
  • 2466-2461(eISSN)
대한방사선방어학회 (The Korean Association for Radiation Protection)
권호 표지
DOI QR코드

DOI QR Code

Public Exposure to Natural Radiation and the Associated Increased Risk of Lung Cancer in the Betare-Oya Gold Mining Areas, Eastern Cameroon

  • Joseph Emmanuel Ndjana Nkoulou II (Centre for Atomic Molecular Physics and Quantum Optics, University of Douala) ;
  • Louis Ngoa Engola (Faculty of Engineering and Technology, University of Buea) ;
  • Guy Blanchard Dallou (Faculty of Science and Techniques, Marien Ngouabi University) ;
  • Saidou (Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research) ;
  • Daniel Bongue (Centre for Atomic Molecular Physics and Quantum Optics, University of Douala) ;
  • Masahiro Hosoda (Department of Radiation Sciences, Hirosaki University Graduate School of Health Sciences) ;
  • Moise Godefroy Kwato Njock (Centre for Atomic Molecular Physics and Quantum Optics, University of Douala) ;
  • Shinji Tokonami (Institute of Radiation Emergency Medicine, Hirosaki University)
  • 투고 : 2021.10.25
  • 심사 : 2022.09.06
  • 발행 : 2023.06.30
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

Background: This study aims to reevaluate natural radiation exposure, following up on our previous study conducted in 2019, and to assess the associated risk of lung cancer to the public residing in the gold mining areas of Betare-Oya, east Cameroon, and its vicinity. Materials and Methods: Gamma-ray spectra collected using a 7.62 cm×7.62 cm in NaI(Tl) scintillation spectrometer during a car-borne survey, in situ measurements and laboratory measurements performed in previous studies were used to determine the outdoor absorbed dose rate in air to evaluate the annual external dose inhaled by the public. For determining internal exposure, radon gas concentrations were measured and used to estimate the inhalation dose while considering the inhalation of radon and its decay products. Results and Discussion: The mean value of the laboratory-measured outdoor gamma dose rate was 47 nGy/hr, which agrees with our previous results (44 nGy/hr) recorded through direct measurements (in situ and car-borne survey). The resulting annual external dose (0.29±0.09 mSv/yr) obtained is similar to that of the previous study (0.33±0.03 mSv/yr). The total inhalation dose resulting from radon isotopes and their decay products ranged between 1.96 and 9.63 mSv/yr with an arithmetic mean of 3.95±1.65 mSv/yr. The resulting excess lung cancer risk was estimated; it ranged from 62 to 216 excess deaths per million persons per year (MPY), 81 to 243 excess deaths per MPY, or 135 excess deaths per MPY, based on whether risk factors reported by the U.S. Environmental Protection Agency, United Nations Scientific Committee on the effects of Atomic Radiation, or International Commission on Radiological Protection were used, respectively. These values are more than double the world average values reported by the same agencies. Conclusion: There is an elevated level of risk of lung cancer from indoor radon in locations close to the Betare-Oya gold mining region in east Cameroon. Therefore, educating the public on the harmful effects of radon exposure and considering some remedial actions for protection against radon and its progenies is necessary.

키워드

과제정보

The Centre for Atomic Molecular Physics and Quantum Optics and Institute of Geological and Mining Research are thanked for their support (logistics and allowances) to carry out field work. Hirosaki University supported the project in terms of Equipment and analysis through Japan Society for the Promotion of Science (JSPS), Grants in Aid for Scientific Research (KAKENHI) Grant Number 26305021. Abdus Salam International Centre for Theoretical Physics (ICTP) is acknowledged for its support (OEA-AC-71). This work was partially supported by the Institute of Geological and Mining Research and Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ) (logistics and allowances) to carry out field work. Hirosaki University supported partially the project in terms of Equipment and analysis through JSPS KAKENHI Grant Number 26305021 and ICTP supported partially the project through the OEA-AC-71 project at CEPAMOQ.

참고문헌

  1. United Nations Scientific Committee on the effects of Atomic Radiation (UNSCEAR). Report to the general assembly with scientific annexes. United Nations; 1993.
  2. Ahmed NK, El-Arabi AG. Natural radioactivity in farm soil and phosphate fertilizer and its environmental implications in Qena governorate, Upper Egypt. J Environ Radioact. 2005;84(1):51-64. https://doi.org/10.1016/j.jenvrad.2005.04.007
  3. Kamunda C, Mathuthu M, Madhuku M. An assessment of radiological hazards from gold mine tailings in the province of Gauteng in South Africa. Int J Environ Res Public Health. 2016;13(1):138.
  4. United States Environmental Protection Agency (USEPA). Code of Federal Regulations. Title 40: protection of environment [Internet]. U.S. Government Publishing Office; 2009 [cited 2023 Jan 18]. Available from: https://www.govinfo.gov/content/pkg/CFR-2009-title40-vol15/xml/CFR-2009-title40-vol15-part70.xml
  5. Ministere des Mines, de l'Industrie et du Developpement Technologique. The capacity building project in the mining sector scrutinized by the world bank [Internet]. MINMIDT; 2018 [cited 2023 Jan 18]. Available from: https://www.minmidt.cm/en/the-capacity-building-project-for-the-mining-sector-scrutenized-by-the-world-bank/
  6. Mining Code. Cameroon Law No2016/017, 14 December 2016 [Internet]. Presidency of the Republic of Cameroon; 2023 [cited 2023 Jan 18]. Available from: https://www.prc.cm/fr/actualites/actes/lois/2316-loi-n-2016-017-du-14-decembre-2016port-antcode-minier-ducameroun?highlight=WyJjb2RlIiwibWluaWVyIiwiY29kZSBtaW5pZXIiXQ==
  7. Ngoa Engola L, Ndjana Nkoulou Ii JE, Hosoda M, Bongue D, Saidou, Akata N, et al. Air absorbed dose rate measurements and external dose assessment by car-borne survey in the gold mining areas of Betare-Oya, Eastern-Cameroon. Jpn J Health Phys. 2018;53(1):5-11. https://doi.org/10.5453/jhps.53.5
  8. Ndjana Nkoulou Ii JE, Ngoa Engola L, Hosoda M, Bongue D, Suzuki T, Kudo H, et al. Simultaneous indoor radon, thoron and thoron progeny measurements in Betare-Oya gold mining areas, Eastern Cameroon. Radiat Prot Dosimetry. 2019;185(3):391-401.
  9. Wessel P, Smith WHF. Free software helps map and display data. Eos. 1991;72(41):441-446. https://doi.org/10.1029/90EO00319
  10. Hosoda M, Tokonami S, Omori Y, Sahoo SK, Akiba S, Sorimachi A, et al. Estimation of external dose by car-borne survey in Kerala, India. PLoS One. 2015;10(4):e0124433.
  11. Inoue K, Hosoda M, Shiroma Y, Furukawa M, Fukushi M, Iwaoka K, et al. Changes of ambient gamma-ray dose rate in Katsushika Ward, metropolitan Tokyo before and after the Fukushima Daiichi Nuclear Power Plant accident. J Radioanal Nucl Chem. 2015;303(3):2159-2163. https://doi.org/10.1007/s10967-014-3669-x
  12. Hosoda M, Inoue K, Oka M, Omori Y, Iwaoka K, Tokonami S. Evaluation of environmental radiation level by car-carbone survey: the outline of the investigation of Aomori Prefecture. Jpn J Health Phys. 2016;51(1):27-40. https://doi.org/10.5453/jhps.51.27
  13. Minato S. A response matrix of a 3"ϕ × 3" NaI(Tl) scintillator for environmental gamma radiation analysis. Rep Gov Ind Res Inst Nagoya. 1978;27(12):384-397.
  14. Minato S. Diagonal elements fitting technique to improve response matrices for environmental gamma ray spectrum unfolding. Radioisotopes. 2001;50(10):463-471. https://doi.org/10.3769/radioisotopes.50.10_463
  15. Dallou GB, Ngoa EL, Ndjana NIIJE, Saidou, Tchuente SYF, Bongue D, et al. Norm measurements and radiological hazard assessment in the gold mining areas of Eastern Cameroon. Radiat Environment Med. 2017;6(1):22-28.
  16. United Nations Scientific Committee on the effects of Atomic Radiation (UNSCEAR). Sources and effects of ionizing radiation. Annex B: exposures from natural radiation sources. United Nations; 2000.
  17. Tokonami S, Takahashi H, Kobayashi Y, Zhuo W. Up-to-date radon-thoron discriminative detector for a large scale survey. Rev Sci Instrum. 2005;76(11):113505.
  18. Tokonami S. Why is 220Rn (thoron) measurement important? Radiat Prot Dosimetry. 2010;141(4):335-339. https://doi.org/10.1093/rpd/ncq246
  19. Kranrod C, Tamakuma Y, Hosoda M, Tokonami S. Importance of discriminative measurement for radon isotopes and its utilization in the environment and lessons learned from using the RADUET monitor. Int J Environ Res Public Health. 2020;17(11):4141.
  20. Pornnumpa C, Oyama Y, Iwaoka K, Hosoda M, Tokonami S. Development of radon and thoron exposure systems at Hirosaki University. Radiat Environment Med. 2018;7(1):13-20.
  21. International Organization for Standardization. ISO16641: 2014. Measurement of radioactivity in the environment-Air-Radon 220: Integrated measurement methods for the determination of the average activity concentration using passive solid-state nuclear track detectors [Internet]. ISO; 2014 [cited 2023 Jan 18]. Available from: https://www.iso.org/standard/57347.html
  22. Tokonami S. Characteristics of thoron (220Rn) and its progeny in the indoor environment. Int J Environ Res Public Health. 2020;17(23):8769.
  23. World Health Organization. WHO launches project to minimize risks of radon [Internet]. WHO; 2005 [cited 2023 Jan 18]. Available from: https://www.who.int/news/item/21-06-2005-who-launches-project-to-minimize-risks-of-radon
  24. International Agency for Research on Cancer. Monographs on the evaluation of carcinogenic risks to humans, No. 43: manmade mineral fibres and radon. International Agency for Research on Cancer; 1988.
  25. Ndjana Nkoulou Ii JE, Manga A, Saidou, German O, Sainz-Fernandez C, Kwato Njock MG. Natural radioactivity in building materials, indoor radon measurements, and assessment of the associated risk indicators in some localities of the Centre Region, Cameroon. Environ Sci Pollut Res Int. 2022;29(36):54842-54854. https://doi.org/10.1007/s11356-022-19781-z
  26. Khatibeh AJAH, Ahmed N, Matiullah. Indoor radon levels in some regions of Jordan and assessment of the associated excess lung cancer risk. Nucleus. 1997;34(1-2):11-15.
  27. U.S. Environmental Protection Agency. Radon reduction methods: a homeowner's guide. US EPA Report EPA-86-005. U.S. Environmental Protection Agency; 1986.
  28. International Commission on Radiological Protection. ICRP Publication 50: Lung cancer risk from indoor exposure to radon daughters. Ann ICRP. 1987;17(1):1-60. https://doi.org/10.1016/0146-6453(87)90026-1