Soils and food crops from a former tin mining location in a high background radiation area on the JosPlateau,
Nigeria were collected and analyzed by gamma spectrometry to measure their contents of 40K, 238U and 232Th. As well as collecting samples, in situ dose rates on farms were measured using a precalibrated
survey meter. Activity concentrations determined in food crops were compared with the local food
derivatives or diets to investigate the possible removal or addition of radionuclides during food preparation
by cooking or other means. Potassium-40 was found to contribute the highest activity in all the food
products. The activity concentration of 40K, 238U and 232Th in local prepared diets ranged between 60
and 494 Bq kg1
, between BDL and 48 Bq kg1 and between BDL and 17 Bq kg1
, respectively. The
internal effective dose to individuals from the consumption of the food types was estimated on the basis
of the measured radionuclide contents in the food crops. It ranged between 0.2 mSv y1 (beans) and
2164 mSv y1 (yam) while the annual external gamma effective dose in the farms due to soil
radioactivity ranged between 228 mSv and 4065 mSv.
2007 Elsevier Ltd. All rights reserved.
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