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Exploring the Root Cause for Chronic Kidney Disease of Unknown Etiology (CKDu) via Analysis of Metal Ion and Counterion Contaminants in Drinking Water: A Study in Sri Lanka

Exploring the Root Cause for Chronic Kidney Disease of Unknown Etiology (CKDu) via Analysis of... Hindawi Journal of Chemistry Volume 2020, Article ID 8670974, 9 pages https://doi.org/10.1155/2020/8670974 Research Article Exploring the Root Cause for Chronic Kidney Disease of Unknown Etiology (CKDu) via Analysis of Metal Ion and Counterion Contaminants in Drinking Water: A Study in Sri Lanka W. P. R. T. Perera , M. D. N. R. Dayananda , and J. A. Liyanage Department of Chemistry, Faculty of Science, University of Kelaniya, Kelaniya 11600, Sri Lanka Correspondence should be addressed to W. P. R. T. Perera; 2017_perera@kln.ac.lk Received 17 July 2020; Revised 5 October 2020; Accepted 7 October 2020; Published 27 October 2020 Academic Editor: Claudio Cameselle Copyright © 2020 W. P. R. T. Perera et al. )is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. )e introduction of elevated amounts of foreign ions into the blood may lead to impairment of the filtration membrane of kidneys and chronic kidney damage. In order to assess the risk of consumption of drinking water (dug well water) in chronic kidney disease of unknown etiology (CKDu), affected areas in Sri Lanka, trace metals, and other counterions in water samples obtained from dug wells were analyzed and compared with a reference area. Drinking water could be the major source that is responsible for entering nephrotoxic ion contaminants into the human body. To achieve the objective, drinking water samples were collected from dug wells in two CKDu endemic areas and a reference area where no CKDu patients were found in a dry season. In the Wewelketiya area (one of the endemic areas), Cd concentrations in 60% of water samples and Pb concentrations in 40% of water samples have exceeded the maximum limit given by Sri Lanka water quality standards. Fluoride concentrations also have exceeded the permissible limits of more than 80% of collected water samples in both CKDu endemic areas. However, none of the water samples in reference areas has reported that Cd, Pb, and fluoride are beyond their maximum permissible limits. Hence, people in the particular CKDu endemic areas are at risk of kidney tissue damage due to long-term exposure to drinking water with elevated levels of some metal ions and counterions. global attention because of the disease’s rapid spread. 1. Introduction However, CKD of unknown etiology CKDu is also prevalent Chronic kidney disease of unknown etiology was first dis- and is progressing rapidly in certain regions of the world, covered in Sri Lanka in the mid-1990s and was mostly especially in Africa, Central America, and Asia [6]. observed among the farmers in the North Central Province )e occurrence of CKDu within the same country will (NCP) of Sri Lanka, and since then, over two decades of a vary with the geographic area. An intimate relationship period, the disease spread dramatically up to the other between water quality and the underlying geology has been farming areas of the country such as Northern, North- recorded repeatedly in various geographical regions of the western, Eastern, Uva, and Central Provinces [1]. Chronic world. Since the CKDu exists in communities where kidney disease (CKD) is a noncommunicable disease that is groundwater is the primary source of drinking water, many related to risk factors such as diabetes or hypertension, past risk factors are hypothesized, for example, unidentified snakebites, and urinary tract infections [2–4]. Another study environmental toxins leading to CKDu [7], chronic pesticide has defined “chronic kidney disease” as either kidney exposure and enhanced level of heavy metals in water and damage or decreased kidney function (decreased GFR) for soil [8], high fluoride levels and potential impacts of AlFx in three months or more [5]. Chronic kidney disease (CKD) is a soil and water [9], and growth of cyanobacteria in water global public health concern, which is attracting increased resources [10, 11]. 2 Journal of Chemistry CKDu was discovered mostly among males in the North selected as CKDu endemic areas for water sampling which Central Province (NCP) of Sri Lanka including Anu- are located in Anuradhapura District and Polonnaruwa radhapura and Polonnaruwa Districts (Table 1), and lately, it district, respectively, in North Central Province, Sri Lanka. has also been detected among women and children. Male Buddahangala GND in Ampara district was selected as the patients are predominantly farmers and/or agricultural la- reference area for the present study. Sampling points for the borers, who are over the age of 40 years [12]. )e distribution drinking water sample collection were selected from shallow of the disease can be associated with some geographical and drinking water wells (dug wells) located in home gardens of socioeconomic factors which have environmental and oc- the residents which are the main sources of water con- cupational origins. NCP of Sri Lanka is a part of the “dry sumption in their daily life. )irty dug wells were selected zone” of Sri Lanka, with a rainfall of ∼1750 to 1000 mm per randomly for the water sampling, and all the sampling sites annum [13], and some studies have shown that the rainfall were located within the same climatic zone (dry zone of Sri map largely overlaps with the region affected by CKDu. Lanka). Sampling locations were recorded in the field using Now, the disease has spread to nearby districts including the global positioning system (GPS) (Figure 1). )e sam- Northwestern, Eastern, and Uva Provinces as well. It is a pling procedure was carried out within August 2019 (dry high burden to the country’s economy due to the high cost of season) for all selected study areas. Triplicated 30 drinking treatments and the poor income of people in remote areas. water samples were collected from each sampling area into Some cohort studies carried out using descriptive hospital uncontaminated Teflon bottles (125 ml) and preserved by records indicated that patients coming to nephrology clinics adding conc. nitric acid (0.10 mL) and stored at 4 C, and in Anuradhapura and Kandy were increasing during the another triplicated 30 drinking water samples were collected period 2001-2002, and the majority of them were CKDu into uncontaminated Teflon bottles (125 ml) without acid- patients [14]. ification and stored at 4 C. )e causes and risk factors for the development of CKDu vary widely. As the CKDu prevails in households where 2.2. Analysis of Water Samples. )e concentration of trace groundwater or well water is the main drinking water source, elements including cadmium, lead, chromium, arsenic, zinc, several risk factors can be hypothesized: (a) chronic expo- copper, sodium, potassium, iron, manganese, cobalt, and sure to chemical pesticides and fertilizers and thereby in- nickel was determined using Inductively Coupled Plasma crease of heavy metals (e.g., Cd, Pb, and As) in water and (b) Mass Spectrometry (ICP-MS-7800-Agilent, Germany). presence of high levels of fluoride and other possible Multielement ICP-MS standards (AccuStandard, USA) were counterions such as phosphates and nitrates [15]. used for instrumental calibration. Two calibration series Ion imbalances of blood and the introduction of a high (1 ppb–50 ppb and 10 ppb to 1000 ppb) were prepared load of foreign ions or molecules into the blood cause using multielement standard. Acidified water samples impairment of the filtration membrane which can result in (with conc. HNO ) were filtered through 0.45 µm syringe protein denaturation. )ose protein molecules pass into the filters before the insertion to the ICP-MS instrument. urine due to the absence of proper maintenance of pore size Phosphate and nitrate concentration in water samples in the membrane. )e glomerular capillaries progressively were measured by Ion Chromatographic method damage the filtration membrane with the high osmotic according to the US-EPA standard procedures (Method pressure gradients and negatively charged proteoglycans can 9056A). Sodium bicarbonate (CASRN 144-55-8) and also be affected by higher concentrations of cations [16–18]. sodium carbonate (CASRN-497-19-7) were used as an Furthermore, toxins are not filtered out from the blood and elution solution, and sulfuric acid (CASRN-7664-93-9) accumulated in the body. When the dysfunction of kidneys was used as a regeneration solution. ACS Reagent grade occurs partially or completely, the normal body perfor- l000 mg/L stock solutions of nitrate and phosphate were mances are altered resulting in some serious health issues used for the standards for anions prepared for a range of with confusing etiology such as chronic kidney disease of concentrations (0.1 mg/L–10 mg/L). Each standard and unknown etiology (CKDu) [19–21]. collected samples were filtered using 0.22-micrometer )e intention of the current study is to assess the drinking nylon filters. Samples were introduced, under the flow rate water quality by evaluating the levels of toxic metals and of 0.7 mL/min into the Ion Chromatograph (Metrohm Eco selected counterions in dug wells of CKDu endemic areas IC). Fluoride concentrations of water samples were compared with a reference area (CKDu nonendemic areas) measured as on-site measurements using calibrated and comment on the risk of consumption of the drinking fluoride meter (Eutech Instrument, pH 510), and when water in selected areas based on Sri Lankan water quality taking the readings, TISAB (III) buffer was used with standards. Besides, the study aims to explore the evidence to water sample in 1 : 1 ratio in order to stabilize the pH of the the link of consumption of well water and the prevalence of medium. Magnesium and calcium concentrations in water kidney disease in selected CKDu endemic areas. samples were determined using a flame atomic absorption spectrophotometer (GBC 5000). A series of standard metal solutions were prepared (10 ppm–500 ppm) sepa- 2. Methodology rately using both Mg and Ca metal ion standards 2.1. Sample Collection. Based on the information obtained (1000 ppm, Bibby Scientific) to obtain the calibration from the Ministry of Health, Sri Lanka, Wewalketiya Grama- curve, and the concentration of Mg and Ca of each water Niladhari division (GND) and Ambagaswewa GND were sample was determined. Journal of Chemistry 3 Table 1: CKDu patients in high-risk areas for chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. District Risk-AGA divisions 2014 2015 Ampara Dehiattakandiya, Maha oya 493 468 Anuradhapura All divisions 8903 8412 Polonnaruwa All divisions 3483 5018 Badulla Rideemaliyadda, Mahiyangana 1010 943 Kurunegala Polpithigama 561 1660 Matale Wilgamuwa 803 1107 Monaragala )anamalwila, Wellawaya, Buttala 246 794 Mullaitivu Welioya 333 486 Vavuniya Vavuniya south, Cheddikulam 163 1933 Trincomalee Padavi siripura, Gomarakadawala 484 426 Hambanthota Tissamharama, Lunugamvehera 0 205 Total 16479 21452 Source: Ministry of Health, Nutrition and Indigenous Medicine, Sri Lanka, 2016. S19 S18 S17 S16 WK_3 S15 S30 WK_7 S14 S13 S12 S11 S28 WK_22 S10 S9 S27 WK_24 S8 WK_5 S7 S26 S29 S22 S24 S21 S20 WK_4 S25 WK_8 WK_10 WK_11 WK_14 Ambagaswewa WK_25 S1 S2 WK_2 S3 WK_29 S5 S6 S4 WK_30 0 0.15 0.3 0.6 0.9 1.2 0 0.15 0.3 0.6 0.9 1.2 Kilometers Kilometers Sampling points Sampling points Wewelketiya_GND Ambagaswewa GND (a) (b) Figure 1: )e distribution of sampling points (Aquifer) which were located in the CKDu prevailed areas: (a) Ambagaswewa GND, Madirigiriya DSD, Polonnaruwa District and (b) Wewalketiya GND, Rambewa DSD, Anuradhapura District, Sri Lanka. 2.3. Geographical Data Treatment and Statistical Data samples which are obtained from the Ambagaswewa GND Analysis. ArcGIS 10.2.2 software package was used to (Madirigiriya DSD in Pollonnaruwa district), Wewalketiya perform surface interpolation for all sampling sites using GND, (Rambewa DSD, in Anuradhapura district), and the estimated mean values to measure the impact of water reference site (Buddhangala GND in Ampara district), re- contamination in the study area. Statistical analysis was done spectively, compared with the permissible limits [22]. When using SPSS Statistics software. Descriptive statistics were considering the causative factors of CKDu, toxic metals are performed on the data sets and a paired t-test was carried out the most important concern including cadmium, chromium, to determine the differences or similarities of the chemical and lead. Cadmium traces naturally occur in phosphate and parameters recorded in each sampling location. have been shown to get into water, soil, and also food through fertilizer application. Cadmium is present as an impurity in phosphate fertilizers and refined petroleum 3. Results and Discussion products [23]. According to Sri Lanka drinking water quality standards, the maximum permissible level (MPL) of cad- Chronic renal failure has recently shown a significant in- crease in some areas in the Anuradhapura and Pollonnaruwa mium (Cd) is 3.000 µg/L [22]. In the present study, 60% of the selected dug wells in Wewalketiya GND in the Anu- districts. Table 2 summarizes the results of trace metals and some of the counterion concentrations of selected well water radhapura district showed elevated Cd levels which exceed 4 Journal of Chemistry Table 2: Descriptive statistics of the chemical composition of well water samples in all the sampling locations: Ambagaswewa GND in Polonnaruwa district, Wewalketiya GND in Anuradhapura district, and reference site (Buddangala GND in Ampara district). Ambagaswewa GND Wewalketiya GND Reference site (Buddhangala GND) Concentration of variables SLS standards SLS 614 : 2013 Mean SD Minimum Maximum Mean SD Minimum Maximum Mean SD Minimum Maximum Cd (g/L) 0.178 0.162 ND 0.660 3.440 2.072 1.120 9.350 0.124 0.008 0.030 0.340 3 Pb (μg/L) 1.229 1.537 ND 6.080 5.422 3.687 1.000 17.350 1.368 0.196 0.000 7.420 10 Cr (μg/L) 0.203 0.423 ND 1.880 11.510 36.860 1.000 48.000 ND ND ND ND 50 As (μg/L) 0.336 0.414 ND 1.650 ND ND ND ND 0.161 0.065 ND 2.850 10 Zn (μg/L) 3.138 5.451 ND 22.59 50.93 20.97 20.00 87.60 4.793 0.790 ND 33.44 3000 Cu (μg/L) 6.470 19.04 ND 175.0 10.61 25.82 3.210 250.0 3.990 1.230 0.210 106.0 1000 Ca (mg/L) 74.10 15.50 ND 135.0 90.7 72.1 11.0 288.0 23.90 14.64 ND 39.83 100 Mg (mg/L) 18.51 25.15 ND 89.57 41.46 31.68 10.00 112.6 16.14 11.90 90.00 156.5 30 Na (mg/L) 1266 1682 205.0 8905 1518 2099 126.0 8845 3684 5175 114.0 8382 200 K (mg/L) 505.4 379.6 0.000 1403 119.2 36.50 14.20 555.3 640.0 582.0 0.000 1832 N/A Fe (mg/L) 6.814 3.957 2.250 17.46 20.27 13.26 6.680 64.38 28.10 95.00 1.000 526.5 0.3 Mn (mg/L) 21.36 44.56 0.130 166.3 11.09 8.540 1.080 41.59 29.80 79.40 0.200 340.2 0.3 Co (mg/L) 0.019 0.072 0.000 0.383 ND ND ND ND ND ND ND ND N/A Ni (mg/L) ND ND ND ND ND ND ND ND ND ND ND ND 0.02 Fluoride (mg/L) 1.260 0.654 0.320 3.160 1.370 0.658 0.220 3.020 0.505 0.081 0.100 3.200 1 Phosphate (mg/L) ND ND ND ND ND ND ND ND ND ND ND ND 2.0 Nitrate (mg/L) 2.520 1.475 0.220 5.890 0.669 0.348 0.150 1.290 1.127 ND 0.110 3.330 50 ND: not detected; N/A: not available. Journal of Chemistry 5 )e health effects due to hard water or bicarbonates and the MPLs. However, drinking water samples obtained from Ambagaswewa GND, Pollonnaruwa district, showed the low sulfates of calcium (Ca) and magnesium (Mg) are significant, and 100 mg/L [22] for Ca and 30 mg/L [22] for Mg are levels of Cd which have not exceeded the MPLs, and also none of the water showed Cd level exceeding the MPLs in the recommended for drinking water. )e results which have reference area. been obtained from the sample analysis show variations in However, previously published reports have interpreted Ca and Mg concentrations in selected dug wells in Amba- that long-term exposure to Cd via drinking water persists in gaswewa and Wewelketiya, and most of the samples have the kidney and can possibly cause kidney failure through reported that Ca and Mg concentrations are beyond the several pathways [24, 25], because both renal proximal tu- MPLs in those CKDu endemic areas. However, in the ref- erence area, the mean concentrations of Ca and Mg have bular damage and decline in glomerular filtration rate (GFR) in humans are due to chronic exposure to Cd [24, 25]. )e been reported to be 23.09 (±14.63) mg/L and 16.14 (±11.90) mg/L, respectively, indicating the low values than CKDu cadmium distribution along the sampling sites in particular GNDs is shown in Figure 2 and cadmium concentrations endemic areas. Long-term exposure to the Ca and Mg ions via drinking water may adversely affect kidney dysfunctions were significantly (p � 0.05) higher in Wewalketiya GND with respect to the reference area. But the Cd concentrations modifying the risk for calcium stones and increasing the risk were not significantly different from the reference in of calcium-containing kidney stones [30]. Ambagaswewa GND. )e increase in geochemical mobility Fluoride can occur naturally in water above desirable of Cd can be seen under acidic environmental conditions levels. Fluoride also has been proposed as a cause of CKDu with the land application of fertilizers and pesticides which [9, 31, 32], and according to Sri Lanka drinking water quality increases the total concentration of Cd in agricultural soils. standard, the maximum permissible level (MPL) of fluoride (F) is 1.0 mg/L [22]. However, the higher fluoride levels in Acidification of soils and surface waters increases the geo- chemical mobility of Cd. Cadmium (Cd) has been suggested the collected drinking water samples (Figure 3) were recorded in Wewalketiya GND (average: 1.370± 0.658 mg/L) as a possible factor contributing to the disease, and the source of contamination can be associated with triple su- and Aambagaswewa GND (average: 1.260± 0.654 mg/L) compared to the reference area (average: 0.505± 0.765 mg/ perphosphate (TSP) application in paddy and other crop cultivations because TSP use is widespread throughout the L), and both CKDu endemic areas have exceeded the MPLs agricultural sector in Sri Lanka and especially in the disease of fluoride in the collected drinking water samples. )e prevailed areas [26]. variations of fluoride levels in all sampling locations are According to the results of the present study, the lead shown in Figure 3. Furthermore, 80% of the samples in levels in Ambagaswewa GND are reported to be 6.080 μg/L Ambagaswewa GND and 95% of samples in Wewalketiya as maximum value with an average of 1.229± 1.537 μg/L, GND were contaminated with fluoride which has exceeded the standard limits [22]. and the lead levels in Wewalketiya GND ranged from 1.000 μg/L to 17.350 ppb with the average of Excessive and long-term exposure to fluoride can be directly related to kidney tissue damage because high 5.422± 3.687 μg/L (Table 2). Even though dug well water samples in Wewalketiya GND showed a huge variation of Pb fluoride zones for groundwater overlap with CKDu-prev- concentrations, 40% of collected samples have exceeded the alent regions in NCP [31]. Patients with reduced glomerular MPLs of Pb, and in case of renal failure, it was reported that filtration rate are having an increased risk of chronic fluoride chronic exposure to Pb can lead to nephrotoxicity charac- toxicity because they have less ability to excrete fluoride via terized by renal effects, such as glomerular sclerosis, inter- urine [33]. According to the dose–effect relationship be- stitial fibrosis, and proximal tubular nephropathy [27] which tween fluoride levels and CKDu [34], unexpected effects of have been commonly observed among the patients with fluoride on cellular systems have been investigated by CKDu in Sri Lanka [23]. Agalakova and Gusev [35] which clearly reveal that fluoride can affect oxidative stress, intracellular redox homeostasis, Apart from that, ranges of Cr concentrations of selected dug wells in Ambagaswewa and Wewelketiya areas were lipid peroxidation, protein synthesis inhibition, gene ex- pression alteration, and apoptosis. reported to be 0.203–0.423 μg/L and 11.5–48.00 μg/L, re- spectively, and all values were below the MPLs. But in the A range of geological factors such as dissolution rates reference area, none of the selected water resources has been and residence times of fluoride-bearing rocks can be related contaminated with Cr. In both humans and animals, to higher fluoride levels in shallow wells in those areas. )e chromium (III) is found as an essential nutrient that plays a minerals, namely, charnockite, granitic, hornblende, and valuable key role in fat, glucose, and protein metabolism, biotitic gneisses [11, 36], and also fluoride-bearing minerals and it is done by the action of insulin [28]. Although such as micas, pyroxene, fluorite, tourmaline, topaz, sphene, and apatite can enhance the fluoride levels in soil [37]. chromium (III) has been found as an essential nutrient, both acute and chronic exposure to high levels via inhalation, Fluoride in the water can be a potential causal factor in the development of the disease because of not only the impacts ingestion, or dermal contact may result in adverse health effects. )e kidney is, therefore, one of the main targeting of fluoride itself but also its interaction with other ionic constituents such as Ca, Na, and possibly Mg that are present organs for Cr in acute high doses and chronic cumulative exposure. In addition to that, renal damage and dysfunction in the drinking water [11]. caused due to chronic Cr exposure could involve both the In particular, collected water samples were having high glomerular and tubule [29]. ionic content with the presence of high amounts of main 6 Journal of Chemistry 4.500 4.000 3.781 3.6607 3.615 3.551 3.56 3.55667 3.5266 3.54 3.492 3.5003 3.458 3.482 3.467 3.47 3.481 3.472 3.48 3.462 3.48 3.43 3.45333 3.423333 3.4 3.408 3.402 3.372 3.363 3.500 2.975 2.98 2.973 3.000 2.500 2.000 1.500 1.000 0.500 0.000 Sampling sites of Wewalketiya GND, Anuradhapura. (a) 0.400 0.350 0.33667 0.28333 0.300 0.27667 0.256 0.24333 0.250 0.22333 0.21667 0.2085 0.205 0.200 0.18667 0.182 0.183 0.18 0.1767 0.1763 0.1667 0.159 0.15667 0.15333 0.15 0.15 0.14333 0.150 0.138 0.12667 0.12333 0.11667 0.109 0.105 0.103 0.103 0.100 0.050 0.000 Sampling sites of Ambagaswewa GND, Pollonnaruwa. (b) Figure 2: Continued. Mean Cd concentration (ppb) Mean Cd concentration (ppb) AM1 WK 1 AM2 WK 2 AM3 WK 3 AM4 WK 4 AM5 WK 5 AM6 WK 6 AM7 WK 7 AM8 WK 8 AM9 WK 9 AM10 WK 10 AM11 WK 11 AM12 WK 12 AM13 WK 13 AM14 WK 14 AM15 WK 15 AM16 WK 16 AM17 WK 17 AM18 WK 18 AM19 WK 19 AM20 WK 20 AM21 WK 21 AM22 WK 22 AM23 WK 23 AM24 WK 24 AM25 WK 25 AM26 WK 26 AM27 WK 27 AM28 WK 28 AM29 WK 29 AM30 WK 30 Journal of Chemistry 7 0.400 0.34667 0.342 0.350 0.323 0.28 0.300 0.25 0.24 0.250 0.22333 0.2033 0.19667 0.200 0.1533 0.150 0.1267 0.117 0.10333 0.08667 0.09667 0.08667 0.073 0.100 0.07333 0.065 0.063 0.053 0.047 0.04 0.04667 0.033 0.035 0.050 0.02333 00 0 0.000 Sampling sites of Buddangala GND, Ampara. (c) Figure 2: Cadmium concentrations in drinking water samples collected from (a) sampling sites of Wewelketiya GND, in Anuradhapura district, (b) sampling sites of Ambagaswewa GND, in Polonnaruwa district, and (c) sampling sites of Buddangala GND (Reference) in Ampara district. 18.000 16.000 14.000 12.000 10.000 8.000 6.000 4.000 2.000 0.000 123456789 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Site number Ampara Ambagaswewa Wewalketiya Figure 3: Variations of fluoride concentrations along the sampling points in the reference site (Buddangala) and disease prevalence areas (Ambagaswewa and Wewalketiya). ions such as Na+ and K+ which are normally found in water. potassium, sodium, magnesium, and calcium and anions )e increased iconicity of drinking water can influence the such as fluoride and phosphates play a major role which are depletion of water molecules near the kidney membrane, present in higher contents in collected drinking water changing water activity and ion activity, osmotic activity, samples from sampling locations [21]. Fertilizer runoff and hydrophobic interactions. When ranking the ions by which contains most of those ionic agents can contribute to their capacity to denature proteins, the cations including the pollution of drinking water sources in that area. Flouride concentration (ppm) Mean Cd concentration (ppb) S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23 S24 S25 S26 S27 S28 S29 S30 8 Journal of Chemistry Similarly, some anions such as fluoride and phosphates are Conflicts of Interest the most active in protein denaturation, while nitrates are )e authors declare that they have no known competing the least effective. Alteration of the composition and hy- financial interests or personal relationships that could have drology of the soil may lead to increased ionicity of adjacent appeared to influence the work reported in this paper. water sources. )e alternating reducing and oxidizing conditions (depending on the environmental and climate conditions of the areas) of soil promote the addition of Acknowledgments iron (Fe) and manganese (Mn) into the soil solution which )e authors would like to acknowledge the National In- would get partly leached out into the water table which is stitute of Fundamental Studies (NIFS), Kandy, Sri Lanka, indicated by the results of having high Fe and Mn contents and would like to thank Mrs. Sachini Rathnasekara and Mr. in all sampling locations (Table 2). )ose redox fluctua- Sudesh Hemal for providing language help, writing assis- tions of soil may decrease the pH of the solution due to tance, and proofreading the article and Amila some nonequilibrium ionic processes such as the con- T. Kannangara, Amitha Suriyaarachchi, and Erandi version of carbonate to bicarbonate and reaction with Udayasiri for supporting the analysis of water samples. )is ambient carbon dioxide (CO ). pH reduction of the soil research was funded by the research project PS/DSP/CKDU/ solution will lead to the release of soil-bound toxic heavy 06/3.5 titled “Establish a CKDu Information and Research metals and those are added to the water sources in those Center at the University of Kelaniya, Sri Lanka.” areas. Intensive usage of chemical fertilizers and pesti- cides is also responsible for the reduction of soil pH levels References [17, 21]. )e kidney needs “good” drinking water [38–40]. It can [1] H. Ranasinghe and M. 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Exploring the Root Cause for Chronic Kidney Disease of Unknown Etiology (CKDu) via Analysis of Metal Ion and Counterion Contaminants in Drinking Water: A Study in Sri Lanka

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Copyright © 2020 W. P. R. T. Perera et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Hindawi Journal of Chemistry Volume 2020, Article ID 8670974, 9 pages https://doi.org/10.1155/2020/8670974 Research Article Exploring the Root Cause for Chronic Kidney Disease of Unknown Etiology (CKDu) via Analysis of Metal Ion and Counterion Contaminants in Drinking Water: A Study in Sri Lanka W. P. R. T. Perera , M. D. N. R. Dayananda , and J. A. Liyanage Department of Chemistry, Faculty of Science, University of Kelaniya, Kelaniya 11600, Sri Lanka Correspondence should be addressed to W. P. R. T. Perera; 2017_perera@kln.ac.lk Received 17 July 2020; Revised 5 October 2020; Accepted 7 October 2020; Published 27 October 2020 Academic Editor: Claudio Cameselle Copyright © 2020 W. P. R. T. Perera et al. )is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. )e introduction of elevated amounts of foreign ions into the blood may lead to impairment of the filtration membrane of kidneys and chronic kidney damage. In order to assess the risk of consumption of drinking water (dug well water) in chronic kidney disease of unknown etiology (CKDu), affected areas in Sri Lanka, trace metals, and other counterions in water samples obtained from dug wells were analyzed and compared with a reference area. Drinking water could be the major source that is responsible for entering nephrotoxic ion contaminants into the human body. To achieve the objective, drinking water samples were collected from dug wells in two CKDu endemic areas and a reference area where no CKDu patients were found in a dry season. In the Wewelketiya area (one of the endemic areas), Cd concentrations in 60% of water samples and Pb concentrations in 40% of water samples have exceeded the maximum limit given by Sri Lanka water quality standards. Fluoride concentrations also have exceeded the permissible limits of more than 80% of collected water samples in both CKDu endemic areas. However, none of the water samples in reference areas has reported that Cd, Pb, and fluoride are beyond their maximum permissible limits. Hence, people in the particular CKDu endemic areas are at risk of kidney tissue damage due to long-term exposure to drinking water with elevated levels of some metal ions and counterions. global attention because of the disease’s rapid spread. 1. Introduction However, CKD of unknown etiology CKDu is also prevalent Chronic kidney disease of unknown etiology was first dis- and is progressing rapidly in certain regions of the world, covered in Sri Lanka in the mid-1990s and was mostly especially in Africa, Central America, and Asia [6]. observed among the farmers in the North Central Province )e occurrence of CKDu within the same country will (NCP) of Sri Lanka, and since then, over two decades of a vary with the geographic area. An intimate relationship period, the disease spread dramatically up to the other between water quality and the underlying geology has been farming areas of the country such as Northern, North- recorded repeatedly in various geographical regions of the western, Eastern, Uva, and Central Provinces [1]. Chronic world. Since the CKDu exists in communities where kidney disease (CKD) is a noncommunicable disease that is groundwater is the primary source of drinking water, many related to risk factors such as diabetes or hypertension, past risk factors are hypothesized, for example, unidentified snakebites, and urinary tract infections [2–4]. Another study environmental toxins leading to CKDu [7], chronic pesticide has defined “chronic kidney disease” as either kidney exposure and enhanced level of heavy metals in water and damage or decreased kidney function (decreased GFR) for soil [8], high fluoride levels and potential impacts of AlFx in three months or more [5]. Chronic kidney disease (CKD) is a soil and water [9], and growth of cyanobacteria in water global public health concern, which is attracting increased resources [10, 11]. 2 Journal of Chemistry CKDu was discovered mostly among males in the North selected as CKDu endemic areas for water sampling which Central Province (NCP) of Sri Lanka including Anu- are located in Anuradhapura District and Polonnaruwa radhapura and Polonnaruwa Districts (Table 1), and lately, it district, respectively, in North Central Province, Sri Lanka. has also been detected among women and children. Male Buddahangala GND in Ampara district was selected as the patients are predominantly farmers and/or agricultural la- reference area for the present study. Sampling points for the borers, who are over the age of 40 years [12]. )e distribution drinking water sample collection were selected from shallow of the disease can be associated with some geographical and drinking water wells (dug wells) located in home gardens of socioeconomic factors which have environmental and oc- the residents which are the main sources of water con- cupational origins. NCP of Sri Lanka is a part of the “dry sumption in their daily life. )irty dug wells were selected zone” of Sri Lanka, with a rainfall of ∼1750 to 1000 mm per randomly for the water sampling, and all the sampling sites annum [13], and some studies have shown that the rainfall were located within the same climatic zone (dry zone of Sri map largely overlaps with the region affected by CKDu. Lanka). Sampling locations were recorded in the field using Now, the disease has spread to nearby districts including the global positioning system (GPS) (Figure 1). )e sam- Northwestern, Eastern, and Uva Provinces as well. It is a pling procedure was carried out within August 2019 (dry high burden to the country’s economy due to the high cost of season) for all selected study areas. Triplicated 30 drinking treatments and the poor income of people in remote areas. water samples were collected from each sampling area into Some cohort studies carried out using descriptive hospital uncontaminated Teflon bottles (125 ml) and preserved by records indicated that patients coming to nephrology clinics adding conc. nitric acid (0.10 mL) and stored at 4 C, and in Anuradhapura and Kandy were increasing during the another triplicated 30 drinking water samples were collected period 2001-2002, and the majority of them were CKDu into uncontaminated Teflon bottles (125 ml) without acid- patients [14]. ification and stored at 4 C. )e causes and risk factors for the development of CKDu vary widely. As the CKDu prevails in households where 2.2. Analysis of Water Samples. )e concentration of trace groundwater or well water is the main drinking water source, elements including cadmium, lead, chromium, arsenic, zinc, several risk factors can be hypothesized: (a) chronic expo- copper, sodium, potassium, iron, manganese, cobalt, and sure to chemical pesticides and fertilizers and thereby in- nickel was determined using Inductively Coupled Plasma crease of heavy metals (e.g., Cd, Pb, and As) in water and (b) Mass Spectrometry (ICP-MS-7800-Agilent, Germany). presence of high levels of fluoride and other possible Multielement ICP-MS standards (AccuStandard, USA) were counterions such as phosphates and nitrates [15]. used for instrumental calibration. Two calibration series Ion imbalances of blood and the introduction of a high (1 ppb–50 ppb and 10 ppb to 1000 ppb) were prepared load of foreign ions or molecules into the blood cause using multielement standard. Acidified water samples impairment of the filtration membrane which can result in (with conc. HNO ) were filtered through 0.45 µm syringe protein denaturation. )ose protein molecules pass into the filters before the insertion to the ICP-MS instrument. urine due to the absence of proper maintenance of pore size Phosphate and nitrate concentration in water samples in the membrane. )e glomerular capillaries progressively were measured by Ion Chromatographic method damage the filtration membrane with the high osmotic according to the US-EPA standard procedures (Method pressure gradients and negatively charged proteoglycans can 9056A). Sodium bicarbonate (CASRN 144-55-8) and also be affected by higher concentrations of cations [16–18]. sodium carbonate (CASRN-497-19-7) were used as an Furthermore, toxins are not filtered out from the blood and elution solution, and sulfuric acid (CASRN-7664-93-9) accumulated in the body. When the dysfunction of kidneys was used as a regeneration solution. ACS Reagent grade occurs partially or completely, the normal body perfor- l000 mg/L stock solutions of nitrate and phosphate were mances are altered resulting in some serious health issues used for the standards for anions prepared for a range of with confusing etiology such as chronic kidney disease of concentrations (0.1 mg/L–10 mg/L). Each standard and unknown etiology (CKDu) [19–21]. collected samples were filtered using 0.22-micrometer )e intention of the current study is to assess the drinking nylon filters. Samples were introduced, under the flow rate water quality by evaluating the levels of toxic metals and of 0.7 mL/min into the Ion Chromatograph (Metrohm Eco selected counterions in dug wells of CKDu endemic areas IC). Fluoride concentrations of water samples were compared with a reference area (CKDu nonendemic areas) measured as on-site measurements using calibrated and comment on the risk of consumption of the drinking fluoride meter (Eutech Instrument, pH 510), and when water in selected areas based on Sri Lankan water quality taking the readings, TISAB (III) buffer was used with standards. Besides, the study aims to explore the evidence to water sample in 1 : 1 ratio in order to stabilize the pH of the the link of consumption of well water and the prevalence of medium. Magnesium and calcium concentrations in water kidney disease in selected CKDu endemic areas. samples were determined using a flame atomic absorption spectrophotometer (GBC 5000). A series of standard metal solutions were prepared (10 ppm–500 ppm) sepa- 2. Methodology rately using both Mg and Ca metal ion standards 2.1. Sample Collection. Based on the information obtained (1000 ppm, Bibby Scientific) to obtain the calibration from the Ministry of Health, Sri Lanka, Wewalketiya Grama- curve, and the concentration of Mg and Ca of each water Niladhari division (GND) and Ambagaswewa GND were sample was determined. Journal of Chemistry 3 Table 1: CKDu patients in high-risk areas for chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. District Risk-AGA divisions 2014 2015 Ampara Dehiattakandiya, Maha oya 493 468 Anuradhapura All divisions 8903 8412 Polonnaruwa All divisions 3483 5018 Badulla Rideemaliyadda, Mahiyangana 1010 943 Kurunegala Polpithigama 561 1660 Matale Wilgamuwa 803 1107 Monaragala )anamalwila, Wellawaya, Buttala 246 794 Mullaitivu Welioya 333 486 Vavuniya Vavuniya south, Cheddikulam 163 1933 Trincomalee Padavi siripura, Gomarakadawala 484 426 Hambanthota Tissamharama, Lunugamvehera 0 205 Total 16479 21452 Source: Ministry of Health, Nutrition and Indigenous Medicine, Sri Lanka, 2016. S19 S18 S17 S16 WK_3 S15 S30 WK_7 S14 S13 S12 S11 S28 WK_22 S10 S9 S27 WK_24 S8 WK_5 S7 S26 S29 S22 S24 S21 S20 WK_4 S25 WK_8 WK_10 WK_11 WK_14 Ambagaswewa WK_25 S1 S2 WK_2 S3 WK_29 S5 S6 S4 WK_30 0 0.15 0.3 0.6 0.9 1.2 0 0.15 0.3 0.6 0.9 1.2 Kilometers Kilometers Sampling points Sampling points Wewelketiya_GND Ambagaswewa GND (a) (b) Figure 1: )e distribution of sampling points (Aquifer) which were located in the CKDu prevailed areas: (a) Ambagaswewa GND, Madirigiriya DSD, Polonnaruwa District and (b) Wewalketiya GND, Rambewa DSD, Anuradhapura District, Sri Lanka. 2.3. Geographical Data Treatment and Statistical Data samples which are obtained from the Ambagaswewa GND Analysis. ArcGIS 10.2.2 software package was used to (Madirigiriya DSD in Pollonnaruwa district), Wewalketiya perform surface interpolation for all sampling sites using GND, (Rambewa DSD, in Anuradhapura district), and the estimated mean values to measure the impact of water reference site (Buddhangala GND in Ampara district), re- contamination in the study area. Statistical analysis was done spectively, compared with the permissible limits [22]. When using SPSS Statistics software. Descriptive statistics were considering the causative factors of CKDu, toxic metals are performed on the data sets and a paired t-test was carried out the most important concern including cadmium, chromium, to determine the differences or similarities of the chemical and lead. Cadmium traces naturally occur in phosphate and parameters recorded in each sampling location. have been shown to get into water, soil, and also food through fertilizer application. Cadmium is present as an impurity in phosphate fertilizers and refined petroleum 3. Results and Discussion products [23]. According to Sri Lanka drinking water quality standards, the maximum permissible level (MPL) of cad- Chronic renal failure has recently shown a significant in- crease in some areas in the Anuradhapura and Pollonnaruwa mium (Cd) is 3.000 µg/L [22]. In the present study, 60% of the selected dug wells in Wewalketiya GND in the Anu- districts. Table 2 summarizes the results of trace metals and some of the counterion concentrations of selected well water radhapura district showed elevated Cd levels which exceed 4 Journal of Chemistry Table 2: Descriptive statistics of the chemical composition of well water samples in all the sampling locations: Ambagaswewa GND in Polonnaruwa district, Wewalketiya GND in Anuradhapura district, and reference site (Buddangala GND in Ampara district). Ambagaswewa GND Wewalketiya GND Reference site (Buddhangala GND) Concentration of variables SLS standards SLS 614 : 2013 Mean SD Minimum Maximum Mean SD Minimum Maximum Mean SD Minimum Maximum Cd (g/L) 0.178 0.162 ND 0.660 3.440 2.072 1.120 9.350 0.124 0.008 0.030 0.340 3 Pb (μg/L) 1.229 1.537 ND 6.080 5.422 3.687 1.000 17.350 1.368 0.196 0.000 7.420 10 Cr (μg/L) 0.203 0.423 ND 1.880 11.510 36.860 1.000 48.000 ND ND ND ND 50 As (μg/L) 0.336 0.414 ND 1.650 ND ND ND ND 0.161 0.065 ND 2.850 10 Zn (μg/L) 3.138 5.451 ND 22.59 50.93 20.97 20.00 87.60 4.793 0.790 ND 33.44 3000 Cu (μg/L) 6.470 19.04 ND 175.0 10.61 25.82 3.210 250.0 3.990 1.230 0.210 106.0 1000 Ca (mg/L) 74.10 15.50 ND 135.0 90.7 72.1 11.0 288.0 23.90 14.64 ND 39.83 100 Mg (mg/L) 18.51 25.15 ND 89.57 41.46 31.68 10.00 112.6 16.14 11.90 90.00 156.5 30 Na (mg/L) 1266 1682 205.0 8905 1518 2099 126.0 8845 3684 5175 114.0 8382 200 K (mg/L) 505.4 379.6 0.000 1403 119.2 36.50 14.20 555.3 640.0 582.0 0.000 1832 N/A Fe (mg/L) 6.814 3.957 2.250 17.46 20.27 13.26 6.680 64.38 28.10 95.00 1.000 526.5 0.3 Mn (mg/L) 21.36 44.56 0.130 166.3 11.09 8.540 1.080 41.59 29.80 79.40 0.200 340.2 0.3 Co (mg/L) 0.019 0.072 0.000 0.383 ND ND ND ND ND ND ND ND N/A Ni (mg/L) ND ND ND ND ND ND ND ND ND ND ND ND 0.02 Fluoride (mg/L) 1.260 0.654 0.320 3.160 1.370 0.658 0.220 3.020 0.505 0.081 0.100 3.200 1 Phosphate (mg/L) ND ND ND ND ND ND ND ND ND ND ND ND 2.0 Nitrate (mg/L) 2.520 1.475 0.220 5.890 0.669 0.348 0.150 1.290 1.127 ND 0.110 3.330 50 ND: not detected; N/A: not available. Journal of Chemistry 5 )e health effects due to hard water or bicarbonates and the MPLs. However, drinking water samples obtained from Ambagaswewa GND, Pollonnaruwa district, showed the low sulfates of calcium (Ca) and magnesium (Mg) are significant, and 100 mg/L [22] for Ca and 30 mg/L [22] for Mg are levels of Cd which have not exceeded the MPLs, and also none of the water showed Cd level exceeding the MPLs in the recommended for drinking water. )e results which have reference area. been obtained from the sample analysis show variations in However, previously published reports have interpreted Ca and Mg concentrations in selected dug wells in Amba- that long-term exposure to Cd via drinking water persists in gaswewa and Wewelketiya, and most of the samples have the kidney and can possibly cause kidney failure through reported that Ca and Mg concentrations are beyond the several pathways [24, 25], because both renal proximal tu- MPLs in those CKDu endemic areas. However, in the ref- erence area, the mean concentrations of Ca and Mg have bular damage and decline in glomerular filtration rate (GFR) in humans are due to chronic exposure to Cd [24, 25]. )e been reported to be 23.09 (±14.63) mg/L and 16.14 (±11.90) mg/L, respectively, indicating the low values than CKDu cadmium distribution along the sampling sites in particular GNDs is shown in Figure 2 and cadmium concentrations endemic areas. Long-term exposure to the Ca and Mg ions via drinking water may adversely affect kidney dysfunctions were significantly (p � 0.05) higher in Wewalketiya GND with respect to the reference area. But the Cd concentrations modifying the risk for calcium stones and increasing the risk were not significantly different from the reference in of calcium-containing kidney stones [30]. Ambagaswewa GND. )e increase in geochemical mobility Fluoride can occur naturally in water above desirable of Cd can be seen under acidic environmental conditions levels. Fluoride also has been proposed as a cause of CKDu with the land application of fertilizers and pesticides which [9, 31, 32], and according to Sri Lanka drinking water quality increases the total concentration of Cd in agricultural soils. standard, the maximum permissible level (MPL) of fluoride (F) is 1.0 mg/L [22]. However, the higher fluoride levels in Acidification of soils and surface waters increases the geo- chemical mobility of Cd. Cadmium (Cd) has been suggested the collected drinking water samples (Figure 3) were recorded in Wewalketiya GND (average: 1.370± 0.658 mg/L) as a possible factor contributing to the disease, and the source of contamination can be associated with triple su- and Aambagaswewa GND (average: 1.260± 0.654 mg/L) compared to the reference area (average: 0.505± 0.765 mg/ perphosphate (TSP) application in paddy and other crop cultivations because TSP use is widespread throughout the L), and both CKDu endemic areas have exceeded the MPLs agricultural sector in Sri Lanka and especially in the disease of fluoride in the collected drinking water samples. )e prevailed areas [26]. variations of fluoride levels in all sampling locations are According to the results of the present study, the lead shown in Figure 3. Furthermore, 80% of the samples in levels in Ambagaswewa GND are reported to be 6.080 μg/L Ambagaswewa GND and 95% of samples in Wewalketiya as maximum value with an average of 1.229± 1.537 μg/L, GND were contaminated with fluoride which has exceeded the standard limits [22]. and the lead levels in Wewalketiya GND ranged from 1.000 μg/L to 17.350 ppb with the average of Excessive and long-term exposure to fluoride can be directly related to kidney tissue damage because high 5.422± 3.687 μg/L (Table 2). Even though dug well water samples in Wewalketiya GND showed a huge variation of Pb fluoride zones for groundwater overlap with CKDu-prev- concentrations, 40% of collected samples have exceeded the alent regions in NCP [31]. Patients with reduced glomerular MPLs of Pb, and in case of renal failure, it was reported that filtration rate are having an increased risk of chronic fluoride chronic exposure to Pb can lead to nephrotoxicity charac- toxicity because they have less ability to excrete fluoride via terized by renal effects, such as glomerular sclerosis, inter- urine [33]. According to the dose–effect relationship be- stitial fibrosis, and proximal tubular nephropathy [27] which tween fluoride levels and CKDu [34], unexpected effects of have been commonly observed among the patients with fluoride on cellular systems have been investigated by CKDu in Sri Lanka [23]. Agalakova and Gusev [35] which clearly reveal that fluoride can affect oxidative stress, intracellular redox homeostasis, Apart from that, ranges of Cr concentrations of selected dug wells in Ambagaswewa and Wewelketiya areas were lipid peroxidation, protein synthesis inhibition, gene ex- pression alteration, and apoptosis. reported to be 0.203–0.423 μg/L and 11.5–48.00 μg/L, re- spectively, and all values were below the MPLs. But in the A range of geological factors such as dissolution rates reference area, none of the selected water resources has been and residence times of fluoride-bearing rocks can be related contaminated with Cr. In both humans and animals, to higher fluoride levels in shallow wells in those areas. )e chromium (III) is found as an essential nutrient that plays a minerals, namely, charnockite, granitic, hornblende, and valuable key role in fat, glucose, and protein metabolism, biotitic gneisses [11, 36], and also fluoride-bearing minerals and it is done by the action of insulin [28]. Although such as micas, pyroxene, fluorite, tourmaline, topaz, sphene, and apatite can enhance the fluoride levels in soil [37]. chromium (III) has been found as an essential nutrient, both acute and chronic exposure to high levels via inhalation, Fluoride in the water can be a potential causal factor in the development of the disease because of not only the impacts ingestion, or dermal contact may result in adverse health effects. )e kidney is, therefore, one of the main targeting of fluoride itself but also its interaction with other ionic constituents such as Ca, Na, and possibly Mg that are present organs for Cr in acute high doses and chronic cumulative exposure. In addition to that, renal damage and dysfunction in the drinking water [11]. caused due to chronic Cr exposure could involve both the In particular, collected water samples were having high glomerular and tubule [29]. ionic content with the presence of high amounts of main 6 Journal of Chemistry 4.500 4.000 3.781 3.6607 3.615 3.551 3.56 3.55667 3.5266 3.54 3.492 3.5003 3.458 3.482 3.467 3.47 3.481 3.472 3.48 3.462 3.48 3.43 3.45333 3.423333 3.4 3.408 3.402 3.372 3.363 3.500 2.975 2.98 2.973 3.000 2.500 2.000 1.500 1.000 0.500 0.000 Sampling sites of Wewalketiya GND, Anuradhapura. (a) 0.400 0.350 0.33667 0.28333 0.300 0.27667 0.256 0.24333 0.250 0.22333 0.21667 0.2085 0.205 0.200 0.18667 0.182 0.183 0.18 0.1767 0.1763 0.1667 0.159 0.15667 0.15333 0.15 0.15 0.14333 0.150 0.138 0.12667 0.12333 0.11667 0.109 0.105 0.103 0.103 0.100 0.050 0.000 Sampling sites of Ambagaswewa GND, Pollonnaruwa. (b) Figure 2: Continued. Mean Cd concentration (ppb) Mean Cd concentration (ppb) AM1 WK 1 AM2 WK 2 AM3 WK 3 AM4 WK 4 AM5 WK 5 AM6 WK 6 AM7 WK 7 AM8 WK 8 AM9 WK 9 AM10 WK 10 AM11 WK 11 AM12 WK 12 AM13 WK 13 AM14 WK 14 AM15 WK 15 AM16 WK 16 AM17 WK 17 AM18 WK 18 AM19 WK 19 AM20 WK 20 AM21 WK 21 AM22 WK 22 AM23 WK 23 AM24 WK 24 AM25 WK 25 AM26 WK 26 AM27 WK 27 AM28 WK 28 AM29 WK 29 AM30 WK 30 Journal of Chemistry 7 0.400 0.34667 0.342 0.350 0.323 0.28 0.300 0.25 0.24 0.250 0.22333 0.2033 0.19667 0.200 0.1533 0.150 0.1267 0.117 0.10333 0.08667 0.09667 0.08667 0.073 0.100 0.07333 0.065 0.063 0.053 0.047 0.04 0.04667 0.033 0.035 0.050 0.02333 00 0 0.000 Sampling sites of Buddangala GND, Ampara. (c) Figure 2: Cadmium concentrations in drinking water samples collected from (a) sampling sites of Wewelketiya GND, in Anuradhapura district, (b) sampling sites of Ambagaswewa GND, in Polonnaruwa district, and (c) sampling sites of Buddangala GND (Reference) in Ampara district. 18.000 16.000 14.000 12.000 10.000 8.000 6.000 4.000 2.000 0.000 123456789 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Site number Ampara Ambagaswewa Wewalketiya Figure 3: Variations of fluoride concentrations along the sampling points in the reference site (Buddangala) and disease prevalence areas (Ambagaswewa and Wewalketiya). ions such as Na+ and K+ which are normally found in water. potassium, sodium, magnesium, and calcium and anions )e increased iconicity of drinking water can influence the such as fluoride and phosphates play a major role which are depletion of water molecules near the kidney membrane, present in higher contents in collected drinking water changing water activity and ion activity, osmotic activity, samples from sampling locations [21]. Fertilizer runoff and hydrophobic interactions. When ranking the ions by which contains most of those ionic agents can contribute to their capacity to denature proteins, the cations including the pollution of drinking water sources in that area. Flouride concentration (ppm) Mean Cd concentration (ppb) S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23 S24 S25 S26 S27 S28 S29 S30 8 Journal of Chemistry Similarly, some anions such as fluoride and phosphates are Conflicts of Interest the most active in protein denaturation, while nitrates are )e authors declare that they have no known competing the least effective. Alteration of the composition and hy- financial interests or personal relationships that could have drology of the soil may lead to increased ionicity of adjacent appeared to influence the work reported in this paper. water sources. )e alternating reducing and oxidizing conditions (depending on the environmental and climate conditions of the areas) of soil promote the addition of Acknowledgments iron (Fe) and manganese (Mn) into the soil solution which )e authors would like to acknowledge the National In- would get partly leached out into the water table which is stitute of Fundamental Studies (NIFS), Kandy, Sri Lanka, indicated by the results of having high Fe and Mn contents and would like to thank Mrs. Sachini Rathnasekara and Mr. in all sampling locations (Table 2). )ose redox fluctua- Sudesh Hemal for providing language help, writing assis- tions of soil may decrease the pH of the solution due to tance, and proofreading the article and Amila some nonequilibrium ionic processes such as the con- T. Kannangara, Amitha Suriyaarachchi, and Erandi version of carbonate to bicarbonate and reaction with Udayasiri for supporting the analysis of water samples. )is ambient carbon dioxide (CO ). pH reduction of the soil research was funded by the research project PS/DSP/CKDU/ solution will lead to the release of soil-bound toxic heavy 06/3.5 titled “Establish a CKDu Information and Research metals and those are added to the water sources in those Center at the University of Kelaniya, Sri Lanka.” areas. Intensive usage of chemical fertilizers and pesti- cides is also responsible for the reduction of soil pH levels References [17, 21]. )e kidney needs “good” drinking water [38–40]. It can [1] H. Ranasinghe and M. 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Journal of ChemistryHindawi Publishing Corporation

Published: Oct 27, 2020

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