P. Lenka

Age-dependent dose and health risk due to intake of uranium in drinking water from Jaduguda, India

Uranium is a heavy metal that is not only radiologically harmful but also a well-known nephrotoxic element. In this study, occurrence of uranium in drinking water samples from locations near the uranium mining site at Jaduguda, India, was studied by Laser-induced fluorimetry. Uranium concentrations range from 0.03 ± 0.01 to 11.6 ± 1.3 µg l(-l), being well within the US Environmental Protection Agency drinking water limit of 30 μg l(-1). The ingestion dose due to the presence of uranium in drinking water for various age groups varies from 0.03 to 28.3 μSv y(-1). The excess lifetime cancer risk varies from 4.3×10(-8) to 1.7×10(-5) with an average value of 4.8×10(-6), much less than the acceptable excess lifetime cancer risk of 10(-3) for radiological risk. The chemical risk (hazard quotient) has an average value of 0.15 indicating that the water is safe for drinking.

Suitable gamma energy for gamma-spectrometric determination of 238U in surface soil samples of a high rainfall area in India

The paper presents a systematic study on suitability of various gamma lines for monitoring of (238)U activity in soil samples around a uranium mineralized zone of Kylleng Pyndengsohiong Mawthabah (Domiasiat), Meghalaya in India. The area lies in a plateau region which recieves the highest average annual rainfall (12,000mm) in the world. The geochemical behaviour of the uranium and its daughter products at such wet climatic conditions imposes restrictions to assess (238)U through gamma lines of radon decay products. Soil samples were collected from nine locations around the uranium mineralization zone for analysis. The ratio of the concentration of uranium obtained from gamma energies of radium daughter products to the 63.29keV of (234)Th was found to vary from 1.01 to 2.07, which indicates a pronounced disequilibrium between uranium and radium daughters. The results obtained from various gamma energies were validated from the data generated by Instrumental Neutron Activation Analysis (INAA) technique. The (238)U activities from the two analytical methods show a well fitted regression line with correlation coefficient 0.99 which validates the reliability of 63.29keV energy for estimation of uranium in such conditions.

Concentrations of uranium in drinking water and cumulative, age-dependent radiation doses in four districts of Uttar Pradesh, India

The present work deals with the determination of uranium concentrations in drinking and ground water samples by laser fluorimetry and calculation of cumulative, age-dependent radiation doses to humans. The concentrations were found to be between 0.20 ± 0.03 and 64.0 ± 3.6 μg L−1, with an average of 11.1 ± 1.5 μg L−1, well within the drinking water limit of regulatory bodies. The concentrations of uranium increase with depth of water samples collection. The estimated annual ingestion dose due to the intake of uranium through drinking water for all age groups varied between 0.2 and 137 μSv a−1, with an average of 17.3 μSv a−1. The mean annual ingestion dose is 5% of the global average ingestion dose, for infants, marginally higher than for other age group. Most effective dose values were less than 20 μSv a−1.

Ingestion dose from 238U, 232Th, 226Ra, 40K and 137Cs in cereals, pulses and drinking water to adult population in a high background radiation area, Odisha, India

A natural high background radiation area is located in Chhatrapur, Odisha in the eastern part of India. The inhabitants of this area are exposed to external radiation levels higher than the global average background values, due to the presence of uranium, thorium and its decay products in the monazite sands bearing placer deposits in its beaches. The concentrations of (232)Th, (238)U, (226)Ra, (40)K and (137)Cs were determined in cereals (rice and wheat), pulses and drinking water consumed by the population residing around this region and the corresponding annual ingestion dose was calculated. The annual ingestion doses from cereals, pulses and drinking water varied in the range of 109.4-936.8, 10.2-307.5 and 0.5-2.8 µSv y(-1), respectively. The estimated total annual average effective dose due to the ingestion of these radionuclides in cereals, pulses and drinking water was 530 µSv y(-1). The ingestion dose from cereals was the highest mainly due to a high consumption rate. The highest contribution of dose was found to be from (226)Ra for cereals and drinking water and (40)K was the major dose contributor from the intake of pulses. The contribution of man-made radionuclide (137)Cs to the total dose was found to be minimum. (226)Ra was found to be the largest contributor to ingestion dose from all sources.

Radiological assessment of surface water quality around proposed uranium mining site in India

The gross alpha and gross beta activities were estimated for radiological assessment of surface water quality around the proposed uranium mining site Kylleng Pyndengsohiong Mawthabah (Domiasiat), West Khasi Hills District, Meghalaya situated in a high rainfall area (12,000mm) in India. 189 Surface water samples were collected over different seasons of the year from nine different locations covering around 100km(2). Gross beta activities were found to vary from 144 to 361mBq/L which is much below the prescribed WHO limit of 1000mBq/L for drinking water. Gross alpha activities varied from 61 to 127mBq/L. These values are much below the reported gross alpha values by other countries. In about 7% of the samples the alpha activities remain exceeded the WHO guideline limit of 100mBq/L. Surface water samples collected during the summer season of the year show higher activity whereas low activity was found from samples collected during monsoon season. Results show that all water sources are acceptable as drinking water for human consumption from the radiological point of view, the higher gross alpha concentrations in a few locations remains so only for short duration during the summer season.

Distribution of norm and 137Cs in soils of the Visakhapatnam region, Eastern India, and associated radiation dose

The specific activity of naturally occurring radioactive materials and (137)Cs in surface soils around the new Bhabha Atomic Research Centre site at Visakhapatnam region, Eastern India, has been determined using high-resolution gamma-ray spectrometry as part of a baseline radiological survey. Radiation hazard for the samples was assessed by radium equivalent activity (Raeq) and absorbed gamma dose rate (D). The mean absorbed gamma dose rate was found to be 104.9 nGy h(-1). The average annual effective dose equivalent was found to be 0.13 mSv y(-1).

Source identification of particulate matter and associated intake of elements through inhalation in an industrial area of Odisha, India

Particulate matter concentrations were measured in an industrial region in the Ganjam district of Odisha. The average levels of suspended particulate matter (SPM) were measured to be 142 ± 8 and PM10 of particulate matter with a size of less than 10 micrometers (PM10) to be 50 ± 15 μg m−3. Out of the 14 elements determined, Ca, Na, Mg, Fe, and K contributed more than 95% of the total weight. In enrichment factors, the trace elements, i.e., Zn, Pb, Cd, and Hg were observed to be highly enriched in the SPM and PM10. Factor analysis indicates that more than 75% of the variance was due to five component factors, which have eigenvalues greater than 1. Intake of elements through inhalation route to adults has been estimated.

Daily intake of manganese by local population around Kylleng Pyndengsohiong Mawthabah (Domiasiat), Meghalaya in India

Present work is carried out adjacent to worlds highest rainfall area Kylleng Pyndengsohiong (KP) Mawthabah (Domiasiat), Meghalaya in India to establish the baseline value of manganese intake through dietary route by the local tribe population in view of proposed uranium mining. The locally available food items collected from villages surrounding the proposed uranium mining site at KP Mawthabah (Domiasiat) were analysed using Energy Dispersive X-Ray Fluorescence (EDXRF) Technique. The manganese concentration in different food categories varies from 2.76-12.50 mg kg(-1) in cereals, 1.8-4.20 mg kg(-1) in leafy vegetables, 0.30-13.50 mg kg(-1) in non leafy vegetables, 0.50-15.30 mg kg(-1) in roots and tubers, 0.70-1.50 mg kg(-1) in fruits and 0.12-0.96 mg kg(-1) in flesh food. The mean dietary intake of Mn was found to be 3.83+/-0.25 mg d(-1) compared to Recommended Dietary Allowances (RDAs) of 2-5 mg d(-1). The daily intake of Manganese by the local tribe population is comparable with the value (3.7 mg d(-1)) recommended by International Commission on Radiological Protection (ICRP) for reference man and lower than the intake value observed for Indian and other Asian population.

An assessment of the radiological scenario around uranium mines in Singhbhum East district, Jharkhand, India

The present work deals with the prevalent radiological scenario around uranium-mining sites in the Singhbhum East district of Jharkhand state, India. The concentration of naturally occurring radioactive materials (NORMs) was estimated from 27 soil samples collected around three regions in the study area, namely Bagjata, Turamdih and Jaduguda. The mean activity concentrations of (238)U in Bagjata, Turamdih and Jaduguda regions were found to be 128.6, 95.7 and 49.2 Bq kg(-1), respectively. Similarly for (232)Th and (40)K the activity concentrations were found to be 57.3, 78.4, 68.9 and 530, 425 and 615 Bq kg(-1) in the Bagjata, Turamdih and Jaduguda regions, respectively, which are comparable with other reported values worldwide, except for some high values. The calculated gamma dose rate, obtained from the concentrations of (238)U, (232)Th and (40)K in the samples, was compared with the observed dose rate in air. A good correlation (0.96) was observed between the calculated and the observed gamma dose rate. The annual outdoor effective dose rate was estimated and the values falls between 0.04-0.3, 0.07-0.3 and 0.07-.14 mSv y(-1) with mean values of 0.14, 0.12 and 0.11 mSv y(-1) for the Bagjata, Turamdih and Jaduguda regions, respectively. The terrestrial dose rates in all the three regions are comparable with other reported values worldwide, except for a few high values in Greece, Rio Grande Do Norte (Brazil) and Kalpakkam (India).

Optimization of 210Po estimation in environmental samples using an improved deposition unit

Abstract Measurement of 210Po in environmental matrices is important due to its very high specific activity, present in every compartment of the environment due to a daughter product of uranium (238U), accumulative and highly toxic in nature. Conventional method for 210Po estimation is by auto-deposition onto both sides of a silver disc followed by alpha spectrometry of both the sides. A new deposition unit having the facility to hold the silver disc and magnetic stirring bar has designed and fabricated for 210Po estimation in which only one side is counted. In the conventional method, the total activity is distributed to the both sides of the silver disc and more counting time is required whereas in the improved deposition unit, only one side contain all the activity so that one time counting is required with better statistical significance. The same has been observed in spike recovery and water sample assessment. The tracer recovery in the conventional method was 72% – 88% and 70% – 85% whereas for the new deposition the recovery is 87% – 99% and 78% – 94% for spike recovery study and environmental samples, respectively. Certified tracers were analysed for the assurance of the reliability of the method and the results were in good agreement with the recommended value with a relative error <20%. The MDA of the method is 1.5 mBq for the estimation of 210Po at 3σ confidence level, 86400 s. counting time and 100 ml of water sample, taking the detector efficiency and chemical yield into consideration. The results obtained from both the methods were compared statistically. χ2 test, repeatability parameters, relative bias measurement and linearity test was performed for both the methods. The % difference between the two methods in terms of linearity is 0.2%. From the χ2 test it can be concluded that the measured data by two methods falls within 99% confidence interval. The modified deposition unit enhance the statistical significance, reduce the counting time, improved detection level, accuracy and precision and more suitable for determination of 210Po in environmental samples as the levels in various environmental matrices is very low and close to the method detection level.