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Unregulated artisanal processing and use of conflict minerals is widespread in high background radiation areas of Eastem Africa and there is need for an evidence-based approach to developing appropropriate radiological regulatory frameworks.Extracted coltan is the raw ore taken from soil; processed coltan is obtained after separating soil and coltan using water.We determined the radiogenic and external dose associated with the extraction and processing of columbite-tantalite (coltan) in three different regions of Rwanda using gamma-ray spectrometry and multivariate chemometrics.The average activity concentration of 238U (513 Bq kg-1) and 232Th (57 Bq kg-1) exceed the world average for 238U (35Bq kg-1) and 232Th (30 Bq kg-1),while for 40K (267 Bq kg-1) is below world average of 400 Bq kg-1.Measured absorbed dose rates vary 518.34 - 796.92 nGy h-1 (mean: 666.3±107.4 nGy h-1),522.4 - 820.7 nGy h-1 (mean: 696.6±109.8 nGy h-1),563.8 - 845.7 nGy h-1 (mean: 692.4±104.4 nGy h-1) in Muhanga,Ruli and Ngoma respectively.These doses are twice higher than the values computed based on the natural radionuclide activities in the coltan ore,indicating that most external exposure results from the ambient environment (radioactive dust).The absorbed dose rate values are however 11 times higher than the world average,clearly delineating Rwandas coltan mining belts as HBRA.We calculated effective doses according to the exposure pathways (external exposure due to gamma-rays from radionuclides in the ground,external exposure due to submersions m air containing radioactive dust,intemal exposure due to ingestion and inhalation of radionuclides) and the working scenarios (digging,drying the coltan in open air,grinding,sieving dried coltan).The values of the total effective doses vary 0.0173 - 0.272 mSv y-1 in Muhanga,0.013 - 0.525 mSv y-1 in Ruli and 0.022 - 0.255 mSv y-1 in Ngoma.Inhalation of coltan bearing dust gives rise to the highest dose exposures; estimated up to 0.53 mSv (98 per cent of the total exposure) per annum.The least significant is the extemal exposure from submersion in radiogenically contaminated air.Although processing reduces 40K by a factor of ≈18,it enhances 232Th and 238U by factors of 3 and 5 respectively.Rwandas coltan has therefore important intemational trade implications in terms of radiological quality assurance.Nonetheless artisanal mining of coltan in Rwanda was observed to not significantly contribute to pollution of the environment via radionuclide immobilization from mine tailings as the activities of 40K,232Th and 238U in the mine sediments were equal to those of soils drawn from control locations not associated with the coltan ore rock.Chemometrics analysis of the radionuclides via PCA accurately source-apportioned processed coltan to respective mining areas,showing that ore gamma-ray spectra are complex geochemical fingerprints that can provide a powerful method for the forensic control of illicit trade of coltan.