Radionuclides find their way into the water resources at sites in the vicinity of nuclearfacilities involved in mining, milling, ore separation, purification, etc. The presentedstudy delineates the distribution of radionuclides {Ra and U(nat)} in groundwatersexisting in the vicinity of two proposed uranium mine sites and evaluates their ingestiondose through the intake of drinking water. The study reveals that the U(nat) concentrationin groundwater varied from <0.5 to 11.2μg.l-1 in the Bagjata mining area and from<0.5 to 27.5 μg.l-1 in theBanduhurang mining area, while 226Ra was found in the range of <3.5 to 206 mBq.l-1 and<3.5 to 82 mBq.l-1, respectively, for both areas.Seasonal variation and distribution of radionuclides in the study area did not show anydefinite pattern. A strong positive correlation of U(nat) in groundwater with pH andnegative correlation of 226Ra with pH is shown in the study. The ingestion doseto the public through intake of drinking water is estimated as 9.43μSv.y-1 for Bagjata and 6.28μSv.y-1 for Banduhurang, which is much lower than thereference limit (100 μSv.y-1) given by the WHO.

Ingestion of radionuclides through food intake accounts for a substantial part ofradiation doses and vegetables constitute essential components of the diet, bycontributing protein, vitamins, iron, calcium and other nutrients. Radionuclides can beapprehended in the ecosystem of the East Singhbhum region which is known for its viablegrades of uranium. In the present study, vegetables were collected from the villagesaround the proposed Bagjata mining area and analysed for U(nat), 226Ra,230Th and 210Po. The geometric mean concentration of U(nat),226Ra, 230Th, and 210Po were 0.05, 0.09, 0.17 and 1.12Bq kg-1 fresh weight, respectively. The intake of the radionuclides fromvegetables was found to be 49.58 Bq y-1while the ingestion dose was calculatedto be 11.51 µSv y-1, respectively. The estimated doses are reflecting thenatural background dose via the route of ingestion, which is much belowthe 1 mSv limit set in the new ICRP recommendations. It is lower than the global averageannual radiation dose of 2 400 µSv to man from the natural radiation sources as proposedby UNSCEAR. The total cancer risk due to the consumption of vegetables was calculated tobe 6.65 × 10-9 which is negligible and much lower than the threshold risk valueof 10-6. The study also reveals that water is more conducive forhigh radioactivity occurrence in vegetables compared to soil systems.

Precise and accurate estimation of natural radioactivity is essential in order toappraise the radiation dose to the member of public due to various intakes. In the presentstudy, an attempt has been made to estimate the uranium content in packaged drinking waterby laser induced fluorimetry and then to calculate the committed effective dose. Sixtypackaged drinking water samples of different brands were analysed for uranium content. Thetotal uranium content in these samples was found to be in the range of 0.04–3.88µg l-1. The concentration of uranium is comparable with other reportedworldwide values except a few high values such as 0.5–6000 µg l-1 in Finland,0.1–28 µg l-1 in China, 0.1–40 µg l-1 in Switzerland and 0.04–1400µg l-1 in Jordan and much lower than the drinking water limit of 15µg l-1 (WHO, 2004) and 30 µg l-1 (USEPA, 2000a). The radiationdose due to uranium ingestion through packaged drinking water was found to vary from0.08–3.19 µSv y-1, with an average dose of 1.21 µSv y-1.

Farming on soils situated in high background radiation areas can result to enhanced radiation exposure scenarios and pathways to humans. To assess the likely levels of exposures, farm soil samples were collected from different farmlands in three old tin mining localities (Bitsichi, Bukuru and Ropp) in Jos Plateau Nigeria, known for high radiations. The soil samples were analyzed for the activity concentrations of 226Ra, 232Th and 40K, using gamma-ray spectroscopy. The outdoor annual effective dose rates were calculated using the activity concentrations of the radionuclides and were found to vary from 0.07 mSv to 2.02 mSv across the three localities. Considering dust generation from soil tillage and inadvertent ingestion of soil particles, the likely internal radiation hazards were estimated using conservative dust and soil loading factors. The total average annual effective dose rates due to 226Ra and 232Th that could result from dust inhalation and ingestion of soil particles were 16.9 µSv, 8.1 µSv and 8.8 µSv, respectively for Bitsichi, Bukuru and Ropp. Though these values are about 5% the outdoor exposures to the farmers in those farms and greater than 1 µSv y-1, from the point of view of radiation protection and risk, they are significant. It suffices to say, therefore, that the results of this study will create the possibility of the importance to evaluate the health risk among the farming population and workplace environments which often is not covered by regulations concerning health protection.

Some crops of important nutritive requirements have been collected from farmlands located in Bitsichi an old tin mining town in north central region of Nigeria. The food crops were analyzed in order to determine trace element concentrations level using Neutron Activation Analysis (NAA). The activity concentrations due to natural radionuclides in the food samples and soil samples collected within the root zone of the crops were also determined using gamma-ray spectrometry (GRS). The NAA results obtained showed higher concentration of Potassium among the essential elements in all the crops. Calcium concentration in both maize and Guinea corn was below detection limit and also Zn in Green beans, sweet potato and cassava. The trace elements; Sc, Hf, Sm, and Th, were below detection limit in all the crops except in Green beans. Rubidium (Rb) and lanthanum (La) were below detection limits only in Cabbage. The activity concentrations of the natural radionuclides in the food samples were found to vary between 83 and 129 Bq kg-1 for 40K, 19 and 30 Bq kg-1 for 226Ra and 27 to 41 Bq kg-1 for 232Th. In the soil samples the activity concentrations varied between 177 and 271 Bq kg-1 for 40K, 53 and 96 Bq kg-1 for 226Ra and 73 to 176 Bq kg-1 for 232Th. Results of activity concentration levels of the radionuclides obtained in similar crops collected for control measurements were found to be very low compared to those from the study area. The effective dose due to intake of the food crops considered in the study area was estimated based on the measured activity concentrations of 226Ra and 232Th in the food crops. It was found to vary between 0.01 mSv y-1 (Acha) and 1.35 mSv y-1 (Cassava) with a cumulative total dose estimated as 2.5 mSv y-1. The mining activities in the area are seen to have influenced the concentration of these trace elements and radionuclides in the food crops. However, they are seen not to pose any serious internal health burden due to ingestion given the realities of food choice by individuals in the study area.