Concentrations of uranium in drinking water and ...

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

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Akhilesh Kumar Yadav , Sunil Kumar Sahoo , Swagatika b

c

d

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Mahapatra , A. Vinod Kumar , Govind Pandey , Pradyumna Lenka & R.M. Tripathi

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Department of Mining Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India b

Health Physics Division, Bhabha Atomic Research Centre, Mumbai, India c

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, India d

Civil Engineering Department, Madan Mohan Malaviya Engineering College, Gorakhpur, India Accepted author version posted online: 13 Jun 2014.Published online: 11 Jul 2014.

To cite this article: Akhilesh Kumar Yadav, Sunil Kumar Sahoo, Swagatika Mahapatra, A. Vinod Kumar, Govind Pandey, Pradyumna Lenka & R.M. Tripathi (2014): Concentrations of uranium in drinking water and cumulative, age-dependent radiation doses in four districts of Uttar Pradesh, India, Toxicological & Environmental Chemistry, DOI: 10.1080/02772248.2014.934247 To link to this article: http://dx.doi.org/10.1080/02772248.2014.934247

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Toxicological & Environmental Chemistry, 2014 http://dx.doi.org/10.1080/02772248.2014.934247

Concentrations of uranium in drinking water and cumulative, age-dependent radiation doses in four districts of Uttar Pradesh, India Akhilesh Kumar Yadava,d*, Sunil Kumar Sahoob, Swagatika Mahapatrab, A. Vinod Kumarc, Govind Pandeyd, Pradyumna Lenkab and R.M. Tripathib a Department of Mining Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India; bHealth Physics Division, Bhabha Atomic Research Centre, Mumbai, India; c Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, India; dCivil Engineering Department, Madan Mohan Malaviya Engineering College, Gorakhpur, India

(Received 4 February 2014; accepted 7 June 2014) The present work deals with the determination of uranium concentrations in drinking and ground water samples by laser fluorimetry and calculation of cumulative, agedependent radiation doses to humans. The concentrations were found to be between 0.20 § 0.03 and 64.0 § 3.6 mg L¡1, with an average of 11.1 § 1.5 mg 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 mSv a¡1, with an average of 17.3 mSv 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 mSv a¡1. Keywords: age-dependent radiation dose; laser fluorimeter; natural radioactivity; uranium

1. Introduction Naturally occurring radionuclides of terrestrial origin are mostly primordial radionuclides of the uranium and thorium decay series. Being a primordial radionuclide, uranium is present in every compartment of the environment with a wide variation in concentrations, depending on regional geological formations or prevailing environmental conditions, due to leaching from its natural deposits, release from uranium industries, combustion of coal and other fuels, and use of phosphate fertilizers. Uranium dissolves readily in oxygenrich waters, which accounts for its presence in surface water, groundwater, and the sea. Most dissolved uranium comes from weathering of igneous rocks that form the earth’s original crust (Essien, Sandoval, and Kuroda 1985; Tadmor 1986). Being a radioactive element, it entails radiation exposure to the general population which is inescapable (Almgren, Isaksson, and Barregard 2008). Considering its omnipresent nature, uranium poses some radiation risk to human life according to the present ICRP recommendation (ICRP72 1996). Uranium is both radiologically and chemically toxic, with the exposure dose from drinking water depending upon its solubility. In nature, uranium is predominantly found as oxide of which the hexavalent state is particularly important while almost all tetravalent compounds are insoluble *Corresponding author. Email: [email protected] Ó 2014 Taylor & Francis

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(Rani and Singh 2006). Health effects of uranium are of carcinogenic and non-carcinogenic nature (WHO 1998), based on its radiological risk and the chemical risk as trace metal. When uranium has entered the human body, the radiation dose is delivered through alpha emission. The nephrotoxic heavy metal uranium exerts its detrimental effects by chemical action, mostly on the proximal tubules of humans. Acute exposure of about 0.1 mg kg¡1 body weight to soluble uranium results in transient damage to the kidneys (USEPA 2000). Therefore, estimations of its concentrations in water and food are imperative for assessment of radiation exposure and the public dose and health risk. Exposure to natural alpha emitters due to drinking water consumption may be crucial in certain geological areas (UNSCEAR 2008). The present work deals with the estimation of total uranium content in drinking water and subsequent computation of ingestion dose to humans due to uranium intake in four districts of Uttar Pradesh. The present work is the first study reporting total uranium concentrations in drinking and ground water in the study region. 2. Materials and method 2.1. Sampling Thirty-eight drinking water samples collected from tap, river, bore-well, and open-well drinking water sources were analyzed from four districts of Uttar Pradesh: Khalilabad, Gorakhpur, Maharajganj, and Kushinagar following the IAEA standard protocol (IAEA 1989). The map of the sampling area is shown in Figure 1. One liter of water sample was collected at different depths (0
80 meter) in pre-acid pre-cleaned polyethylene containers and then preserved.

Figure 1. Sampling locations shown in maps of India and Uttar Pradesh.

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2.2. Analytical techniques Glassware used for sample processing was soaked in 10% nitric acid for 15 days and then rinsed thoroughly with double distilled water before use. A reagent blank was considered along with each batch of the sample processing, and concentrations observed in the reagent blank were subtracted from the same batch of samples. Determination of total uranium was carried out in the laboratory of the Environmental Assessment Division, Bhabha Atomic Research Centre, by laser fluorimetry. Details of instrument calibration, optimization of parameters, reagents required, and analytical procedure are given elsewhere (Sahoo et al. 2009).

2.3. Quality assurance and quality control The accuracy and reliability of the method are verified by cross method analysis. Twenty water samples were analyzed by both adsorption stripping voltammetry and laser fluorimetry (Patra et al. 2013). The results are in good agreement with each other and a correlation coefficient of 0.97 has been shown in Figure 2. Precautions were taken to achieve a dust-free laboratory environment and a steady temperature.

3. Results and discussion 3.1. Concentrations of uranium The total uranium concentration in drinking water varied from 0.2 § 0.02 to 64.0 § 3.6 mg L¡l, with an average value of 11.2 § 1.4 mg L¡l. A box-whisker plot is shown in Figure 3. Large variation of the data may be attributed to heterogeneous distribution of uranium concentration in the sampling area. The coefficient of skewness was found to be 2.0, indicating that the data were right skewed. Variations of distribution in uranium

Figure 2. Comparison of the uranium concentration measurement by two techniques: laser fluorimetry and adsorbing stripping voltammetry.

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Figure 3. Box-whisker plot of the total uranium concentration observed.

concentration increase with depth and then decrease, as shown in Figure 4. The highest uranium concentration was observed in the water samples collected from a depth of 30
60 meters. Only three water samples were collected from a depth of 80-meters. The frequency distribution of uranium concentration in drinking water samples is shown in Figure 5. Figure 5 shows that about 18% of the samples contained uranium less than 1 mg L¡l and 61% of the total samples had 1
10 mg L¡l uranium. Ninety percent of the

Figure 4. Distribution of average uranium concentration with depth.

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Figure 5. Frequency and cumulative percentage distribution of uranium concentration.

measured data had values less than 30 mg L¡l, which are consistent with the guideline levels of both WHO and USEPA for uranium in drinking water. Only 2% of the data had values greater than the AERB (AERB 2004) limit of 60 mg L¡l (Figure 6). The uranium concentration observed in the present study is comparable with other studies worldwide (Table 1). However, the uranium concentration in all the water samples from Khalilabad,

Figure 6. Relative distribution of samples with uranium concentration lower than the WHO and USEPA (30 mg L¡1) limits for drinking water.

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Table 1. Uranium concentrations in drinking water reported previously.

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Sl. no.

Country

1 2

Ontario, Canada Central Australia

3 4 5 6 7 8 9

China, Asia Allahabad, India United States India Hyderabad, India Jaduguda, India Khalilabad, Gorakhpur, Maharajganj, and Kushinagar from Uttar Pradesh, India

Range of uranium concentration (mg L¡1) 0.05
4.21 >20.0 0.004
28.0 0.08
471.27 0.012
3.08 0.1
19.6 0.6
82.0 0.03
11.6 0.02
64.0

References OMEE (1996) Hostetler, Wischusen, and Jacobson (1998) UNSCEAR (2008) Rani and Singh (2006) UNSCEAR (2008) Sahoo et al. (2009) Balbudhe et al. (2012) Patra et al. (2013) Present study

Kushinagar, and Maharajganj is well within the recommended limit of 30 mg L¡l (USEPA 2000). 3.2. Age-dependent radiation dose Radiation dose due to intake of uranium through drinking water pathways for different age groups was calculated using ICRP 72 dose coefficients (ICRP72 1996) and prescribed water intake rates for different age groups (DRIs 2005). The ingestion dose due to uranium intake through drinking water pathways was calculated by using the following formula: Ingestion dose ðSv year ¡ 1 Þ ¼ concentration ðBq L ¡ 1 Þ £ intake ðL year ¡ 1 Þ £ dose conversion factor ðSv Bq ¡ 1 Þ The activity concentration of uranium was calculated by using the unit conversion factor (1 mg L¡l D 0.024751 Bq L¡l). The water intake rates assumed for infants 0
6 and 7
12 months old and children 1
3 and 4
8 years old are 0.7, 0.8, 1.3, and 1.7 L day¡1, respectively. The water intake rates assumed for males in the age groups of 9
13, 14
18, and >18 were 2.4, 3.3, and 3.7 L day¡1, respectively. The water intake rates assumed for females in the age group of 9
13, 14
18, and >18 were 2.1, 2.3, and 2.7 L day¡1. During pregnancy and lactation, the water intake rates assumed were 3.0 and 3.8 L day¡1. The estimated annual ingestion dose due to intake of uranium through drinking water for all age groups varied between 0.2 and 137 mSv a¡1 with an average value of 17.2 mSv a¡1. However, the mean annual ingestion dose is only 5% of the global average ingestion dose. Large variations in the dose value can be attributed to the variations in uranium concentration. Table 2 shows the range of ingestion dose due to intake of uranium through drinking water for various age groups. Comparison of the mean annual ingestion dose for various age groups of male and female is presented in Figure 7. The ingestion dose for infants is marginally higher as compared to other age groups because of a relatively

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Table 2. Age
dependent ingestion dose (mSv a¡1) due to intake of uranium. Annually ingested dose due to uranium uptake with drinking water (mSv a¡1) Life stage group

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Infants Children Males

Females

Age

Min.

Max.

0
6 months 7
12 months 1
3 years 4
8 years 9
13 years 14
18 years Adults 9
13 years 14
18 years Adults

0.4 § 0.01 0.5 § 0.02 0.3 § 0.01 0.2 § 0.03 0.3 § 0.04 0.4 § 0.05 0.3 § 0.06 0.3 § 0.03 0.3 § 0.04 0.2 § 0.04 0.2 § 0.05 0.3 § 0.06

137 § 8.5 156 § 14.3 90 § 6.3 78 § 6.2 94 § 7.8 127 § 10.8 96 § 12.1 82 § 6.8 89 § 7.5 70 § 8.8 76 § 9.8 98 § 12.4

Pregnancy Lactation

higher dose coefficient for infants. This means that they are more radiosensitive. (Though the intake of water is less in the case of infants, the dose coefficient is five times more as compared to that for adults.) The dose in the case of males is higher as compared to that for females which is due to higher water intake rates. The higher dose during the lactation period may be attributed to the need of more water in that period. Since 53% of water samples were found to contain less than 5 mg L¡l of uranium, the radiation dose due to uranium intake will be near to the lower bound of the dose range. From the frequency

Figure 7. Ingestion dose variation with age groups.

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Figure 8. Frequency and cumulative percentage distribution of effective dose due to uranium in drinking water.

distribution graph of annual ingestion dose for the adult population (Figure 8), it is clear that most of the effective dose values were less than 20 mSv a¡1.

4. Conclusions This study is the first of its kind where the uranium concentration in drinking water has been reported The uranium concentration in drinking water was found to be 0.2 § 0.03 to 64.0 § 3.6 mg L¡l with an average value of 11.1 § 1.4 mg L¡l. Ninety percent of the measured data have values less than 30 mg L¡l, which is consistent with the guideline level for uranium in drinking water of USEPA. Only 2% of the data have values greater than the AERB (AERB 2004) limit of 60 mg L¡l. The estimated annual ingestion dose due to intake of uranium through drinking water for all age groups varied between 0.2 and 137 mSv a¡1 with an average value of 17.2 mSv a¡1. However, the mean annual ingestion dose is only 5% of the global average ingestion dose. The ingestion dose for infants is marginally higher as compared to other age groups due to a higher dose coefficient for infants on account of their higher radiosensitivity. Fiftythree percent of water samples were found to contain less than 5 mg L¡l of uranium. This leads to the conclusion that the ingestion dose due to uranium intake would be near to the lower bound of the dose range. Therefore, it can be concluded that the drinking water sources in the study region are free of adverse human health risk due to the presence of uranium.

Acknowledgments The corresponding author would like to express sincere thanks to Shri V.D. Puranik, Ex Head, for extending the permission of research work at the Environmental Assessment Division, Bhabha Atomic Research Centre, Mumbai, and to Shri Rameshwar Sharma and Shri Ramraksha Yadav for their encouragement and support during the study.

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506. DRIs (Dietary Reference Intakes). 2005. Dietary Reference Intakes for Water, Potassium, Sodium Chloride, and Sulfate. Panel on Dietary Reference Intakes for Electrolytes and Water. Standing Committee on the Scientific Evaluation of Dietary References Intake. Food and Nutrition Board. Institute of Medicine of the National Academies. Washington, DC: The National Academies Press. Accessed on 28 December 2013. http://www.nap.edu/openbook.php? record_id=10925 Essien, I.O., D.N. Sandoval, and P.K. Kuroda. 1985. “Deposition of Excess Amount of Natural U from the Atmosphere.” Health Physics 48: 325
331. Hostetler, S., J. Wischusen, and G. Jacobson. 1998. Western Water Study (Wiluraratja Kapi): Groundwater Quality in the Papunya-Kintore Region. Canberra: Australian Geological Survey Organisation. IAEA (International Atomic Energy Agency). 1989. Measurement of Radionuclides in Food and the Environment. Technical Report Series 295, Vienna, Austria. Accessed on 30 June 2014. http:// www-pub.iaea.org/MTCD/Publications/PDF/trs295_web.pdf ICRP72 (International Commission on Radiological Protection). 1996. “Age Dependent Doses to the Members of the Public from Intake of Radionuclides Part 5, Compilation of Ingestion and Inhalation Coefficients.”Annals of the ICRP 26 (1): 1
91. OMEE (Ontario Ministry of Environment and Energy). 1996. Monitoring Data for Uranium 1990
1995. Toronto: OMEE Ontario Drinking Water Surveillance Program. Patra, A.C., S. Mohapatra, S.K. Sahoo, P. Lenka, J.S. Dubey, R.M. Tripathi, and V.D. Puranik. 2013. “Age-Dependent Dose and Health Risk Due to Intake of Uranium in Drinking Water from Jaduguda, India.” Radiation Protection Dosimetry 155 (2): 210
216. Rani, A., and S. Singh. 2006. “Analysis of Uranium in Drinking Water Samples Using LaserInduced Fluorimetry.” Health Physics 91 (2): 101
107. Sahoo, S.K., S. Mohapatra, A. Chakrabarty, C.G. Sumesh, V.N. Jha, R.M. Tripathi, and V.D. Puranik. 2009. “Distribution of Uranium in Drinking Water and Associated Age-Dependent Radiation Dose in India.” Radiation Protection Dosimetry 136 (2): 108
113. Tadmor, J. 1986. “Atmospheric Release of Volatilized Species of Radio Elements from Coal-fired Plants.” Health Physics 50: 270
273. UNSCEAR. 2008. United Nations Scientific Committee on the Effect of Atomic Radiation. New York: United Nations General Assembly. USEPA (United States Environmental Protection Agency). 2000. National Primary Drinking Water Regulations: Radionuclides. Federal Register. Vol. 65, no. 236, December 7, 2000. Final Rule. 40 CFR Parts 9, 141, and 142. WHO. 1998. Guidelines for Drinking Water Quality. 2nd ed. Geneva: World Health Organization.