Authors
Yo Ishigaki, Katsumi Shozugawa, Ryo Ichimiya, Harrizki Arie Pradana, Sidik Permana, Kan Shimazaki, Kazunori Hayashi, Adi Rahmansyah Amir Abdullah, Cici Wulandari
Published in
PloS one. Volume 21. Issue 10. Pages e0348187. Epub Oct 05, 2026.
Abstract
Radioactive contamination in residential areas of Bangka Island, Indonesia, a major tin- and rare earth-producing region, has rarely been studied, although material stored near mineral-processing workshops may pose a long-term health risk. We collected 46 soil samples around 9 mineral-processing workshops in the Selindung District, Pangkal Pinang City: residential soils from 20 locations at two depths (n = 40) and 6 workshop-related sediments. High-purity germanium detector analysis showed that 13 of the 40 residential soil samples exceeded the screening criteria of the IAEA Safety Standards Series No. RS-G-1.7 for naturally occurring radioactive material. Residential contamination was highly heterogeneous and was not explained by a simple monotonic distance relationship (Spearman's ρ = -0.12, p = 0.61). Two upper outliers occurred at 5 and 10 m from the nearest workshops, including the maximum residential activity of 12,992 Bq/kg detected at 5 m, in areas frequently accessed by local residents. Five of 17 locations with quantifiable paired measurements (including 1 tied pair; n = 16 for the Wilcoxon signed-rank test) showed higher activity at 20 cm than at 10 cm, and the paired depth difference was not statistically significant (Wilcoxon p = 0.079), indicating an irregular rather than consistently surface-dominated vertical distribution. Screening-level outdoor annual effective doses for the quantifiable residential samples ranged from 0.051 to 8.46 mSv/y (median 0.42 mSv/y), with the maximum obtained 5 m from a workshop. Nuclide composition analysis further revealed that the activity concentrations of the 238U and 232Th series increased with total radioactivity, whereas 40K showed only a weak correlation. Maximum activities of 238U and 232Th approached levels reported by the IAEA for high-purity monazite sand (6,000-20,000 Bq/kg). These findings demonstrate spatial and vertical heterogeneity of technologically enhanced naturally occurring radioactive material in residential zones, indicating a need for site-specific assessment and long-term monitoring.
PMID:
42832485
Bibliographic data and abstract were imported from PubMed on 06 Oct 2026.
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