Abstract
Unexplained or unclear etiology of chronic kidney disease (CKDu) has been reported in Sri Lanka’s North Central Province (NCP) for more than two decades. Meanwhile, high exposure to heavy metals/metalloids and their accumulation are recognized as the origin of many acute and chronic diseases in certain vulnerable human tissues including kidneys. This study evaluates the contamination status of heavy metals/metalloids of the drinking water and agricultural soil in two CKDu endemic areas compared with a reference area in Sri Lanka based on common indexes and attribute of the commonly used fertilizers evaluated to identify the basic sources of toxic metals in the agricultural soil. Mean concentrations of heavy metals/metalloids such as Mn, Co, As, Cd, Pb, Cu, Zn, and Fe in drinking water of CKDu endemic areas were far below Sri Lankan water quality standards (permissible limits). In addition, all sampling locations dropped below the medium range of the heavy metal pollution index of water (HPI 15–40). Geoaccumulation indexes (Igeo) of soil reveal that paddy soil in CKDu endemic areas is being moderately polluted with toxic metals/metalloids such as As, Pb, Cu, Ni, Cr, Zn, and Cd. On the other hand, the application of fertilizers, which contained a high dose of toxic metals, could be the driving force for agricultural soil pollution, and limitless application of low-quality fertilizer would lead to more soil contamination with heavy metals. Hence, hazardous metals can be incorporated into the food chains via contaminated paddy soil.
Highlights
Chronic kidney disease unknown etiology (CKDu) was first discovered in Sri Lanka in the mid-1990s, mainly found among farmers in Sri Lanka’s North Central Province (NCP); since the disease has spread dramatically over a span of two decades, including other agricultural areas of the country such as the North, North West, Eastern, Uva, and Central Provinces [1,2,3]
Geographic “hotspots” of CKDu have emerged in a number of countries, including El Salvador, Guatemala, Mexico, Nicaragua, Bulgaria, Croatia, Serbia, India, and Sri Lanka [5], and it is prevalent among agricultural workers with several symptoms including fatigue, panting, lack of appetite, nausea, and anemia [6]. e studies of CKDu in Sri Lanka are significant because of the increasing number of Sri Lankans who are suffering from CKDu since the 1990s, e.g., more than 50,000 patients diagnosed with late-stage kidney disease, and the majority of these patients are reported from the North Central Province (NCP) [7]
In accordance with the literature, an investigation of 210 children in China found that drinking water with more than 2.00 mg/L fluoride had increased levels of N-acetyl glucosamine (NAG) and y-glutamyl transpeptidase in their urine, both of which are markers of renal tubular damage [22]. e present study has found that mean fluoride contents in the CKDu endemic areas have exceeded the permissible limits for drinking water fluoride (1.00 mg/L) (SLS 614 : 2013) (Figure 1)
Summary
Chronic kidney disease unknown etiology (CKDu) was first discovered in Sri Lanka in the mid-1990s, mainly found among farmers in Sri Lanka’s North Central Province (NCP); since the disease has spread dramatically over a span of two decades, including other agricultural areas of the country such as the North, North West, Eastern, Uva, and Central Provinces [1,2,3]. Ose toxicants exist as clusters in the environment [9] Exposure to those may be linked to conditions such as neurotoxicity in human kidneys. Exposure to metals such as As, Cd, Hg, Cr, Ni, Mn, and Fe present in the drinking water significantly collaborated with the functional and structural integrity of kidneys [10, 11]. High creatinine levels indicate a weak glomerular filtration process which means reduced ability to excrete waste products from the blood through urine [9]
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