Geochemical and isotopic evidences from groundwater and surface water for understanding of natural contamination in chronic kidney disease of unknown etiology (CKDu) endemic zones in Sri Lanka

Abstract

Chronic kidney disease of unknown etiology (CKDu) is the main health issue in the dry zone of Sri Lanka. Despite many studies carried out, causative factors have not been identified yet clearly. According to the multidisciplinary researches carried out so far, potable water is considered as the main causative factor for CKDu. Hence, the present study was carried out with combined isotopic and chemical methods to understand possible relationships between groundwater; the main drinking water source, and CKDu in four endemic areas in the dry zone. Different water sources were evaluated isotopically (H, H andO) and chemically from 2013 to 2015. Results revealed that prevalence of CKDu is significantly low with the groundwater replenished by surface water inputs. It is significantly high with the groundwater stagnated as well as groundwater recharged from regional flow paths. Thus, the origin, recharge mechanism and flow pattern of groundwater, as well as geological conditions which would be responsible for natural contamination of groundwater appear as the main causative factors for CKDu. Therefore, detailed investigations should be made in order to identify the element(s) in groundwater contributing to CKDu. The study recommends providing drinking water to the affected zones using water sources associated with surface waters.

Spatial Variations in the Stable Isotopic Compositions of Surface and Groundwaters across Central Sri Lanka

“…Particularly in the dry zone, evaporative isotopic enrichments of shallow groundwater have been reported by Song et al (1999), Edirisinghe et al (2014), and Edirisinghe et al (2017b). However, groundwater and spring water samples in this study plot along the LMWL, indicating less evaporative isotopic enrichment (Fig.…”

“…The two major cities of Sri Lanka, Colombo (the capital) and Kandy, mostly rely on surface water for public water supply, but some relatively large urban centers also base their water supply on groundwaters (Villholth & Rajasooriyar 2010, Herath & Ratnayake 2007. However, water quality problems such as CKDu (Edirisinghe et al 2017b) and dental fluorosis (Jayawardana et al 2012), caused by drinking groundwater, are on the rise, and access to safe water supplies is becoming an important issue. Thus, a thorough understanding of the hydrological cycles in Sri Lanka is necessary to manage water resources at the regional scale.…”

“…Edirisinghe et al (2017a) revealed seasonal and spatial δ 18 O and δD variations in rainwater due to monsoon and convectional rainfall and identified an isotopic fractionation on the basis of their long-term observations across central and northern Sri Lanka. Basin-scale stable isotopic analyses have also been used to understand the evolution of groundwater quality (Song et al 1999), assess groundwater recharge mechanisms (Edirisinghe et al 2014), and demonstrate the relationship between groundwater and chronic kidney disease of unknown etiology (CKDu) (Edirisinghe et al 2017b).…”

Factors Affecting the Environmentally Induced, Chronic Kidney Disease of Unknown Aetiology in Dry Zonal Regions in Tropical Countries—Novel Findings

“…Analyses of water samples in multiple studies indicated the lack of proposed nephrotoxins in drinking water in both CKDmfo-affected and non-affected regions [8,[68][69][70][71]. Analysed components include HMs (Cd, Pb, As, and Cr), agrochemicals (fertilizers and pesticides), and toxins such as ochratoxin, algae-related toxins, organochlorines, and organophosphates.…”

“…Most people with CKDmfo consume water from household, stagnant shallow wells that are not connected to the underground water table or deep tube wells [6,14]. However, the prevalence of CKDmfo is low among those who consume surface water from dynamic water sources, such as reservoirs, streams, irrigating canals, and natural springs [68,71]. Meanwhile, there is no evidence that well water in Sri Lanka and other CKDmfo-affected countries is contaminated with fertilizers, pesticides, or HMs causing CKDmfo [14,68,[74][75][76].…”