This study presents a comprehensive multi-pathway exposure assessment of residents in a former tin-mining community in Kanchanaburi Province, Thailand, underlain by granitic bedrock. Indoor and outdoor radon (222Rn), thoron (220Rn), and their progeny were measured seasonally, along with terrestrial gamma dose rates, radionuclides in foodstuffs, and 222Rn in drinking water. The annual mean indoor 222Rn concentration was 19 ± 10 Bq \({\text{m}}^{-3}\), well below the global average. In contrast, 220Rn progeny accounted for 83% of the total inhalation dose (0.9 mSv), identifying 220Rn as the dominant inhalation dose contributor within the granitic and thorium-rich environmental setting of E-Tong Village. The annual ingestion dose from drinking water was very low (0.03 mSv). Dietary ingestion was the primary internal exposure pathway (1.47 mSv), driven largely by 210Po in seafood (1.1 mSv). External gamma-emitting radionuclides contributed 0.45 mSv. The total annual effective dose was estimated at 2.8 mSv, consistent with natural background radiation. Comparisons with a control area suggest that the observed dose levels reflected lithological background rather than residual contamination associated with former mining activities. These findings underscore the need to integrate 220Rn progeny measurements into radiological risk assessments of granitic regions in Southeast Asia.
