Ph.D student, Birla Institute of Technology and Science,Pilani,K K Birla Goa campus
Environmental toxicology and its contribution in the development of Chronic Kidney disease
Chronic Kidney disease (CKD) is a global health problem and the 12th leading cause of death worldwide with common risk-factors being diabetes and hypertension .However, recently, a growing concern has aroused about a new-form of CKD not caused by any of these risk-factors termed as CKD of unknown-etiology (CKDu). It is prominent in developing-countries like India, Sri-Lanka and some central-American countries (Costa-Rica, Nicaragua, Panama and El-Salvador).This disease mainly affects kidney's tubular interstitium belonging to the type of Chronic Kidney Disease viz. Chronic tubulo-interstitial nephritis (CTN)which is caused by chronic exposure to environmental-toxins like heavy-metals (lead, arsenic, cadmium), mycotoxins, pesticides (diazinon).
This wave of CKDu-cases has managed to engulf a few villages of the infamous tourist destination of INDIA i.e.Goa specifically the Canacona sub-district for the past two decades. The causation of this mysterious form of disease has remained unknown till the present date and therefore in the quest of finding the cause(s) of this CKDu-disease, a joint-team from NIOH(National Institute of Occupational-Health)and ICMR (Indian Council of Medical-Research)in 2005, checked for role of ochratoxin, arsenic and cadmium (in water and food)in the etiology but nothing conclusive was obtained. Hence we took up the challenge to decipher the etiology of this endemic mysterious-form of CKDu and we hypothesize that the causal factors of this disease in the taluka is related to exposure to environmental toxins as it is unlinked to common causative agents like diabetes and hypertension.
During the course of this study, various potential and newly emerging environmental nephrotoxins and risk-factors of the global CKDu-problem will be analysed using this Indian sub-district as a case-study.The cellular and molecular mechanisms of nephrotoxicity of emerging toxins(viz.silica ,lead etc.) in development of CKDu will be elucidated;with special emphasis being given on the nephrotoxic potential of silica (which has never been explored till the present date). These research results can be extrapolated to the worldwide scale wherein necessary diagnostic,preventive and remediation measures can be undertaken to reduce the future incidences and the global burden of CKDu. This study aims to provide relief from the misery of CKDu which the residents of the Indian sub-district have been enduring for past 25 years.
Abstract: Chronic kidney disease of unknown etiology (CKDU) is endemic among the rural farming communities in several localities in and around the North Central region of Sri Lanka. This is an interstitial type renal disease and typically has an insidious onset and slow progression. This study was conducted to identify the pathological features in the different clinical stages of CKDU. This is a retrospective study of 251 renal biopsies identified to have a primary interstitial disease from regions endemic for CKDU. Pathological features were assessed and graded in relation to the clinical stage. The mean age of those affected by endemic CKDU was 37.3 ± 12.5 years and the male to female ratio was 3.3:1. The predominant feature of stage I disease was mild and moderate interstitial fibrosis; most did not have interstitial inflammation. The typical stage II disease had moderate interstitial fibrosis with or without mild interstitial inflammation. Stage III disease had moderate and severe interstitial fibrosis, moderate interstitial inflammation, tubular atrophy and some glomerulosclerosis. Stage IV disease typically had severe interstitial fibrosis and inflammation, tubular atrophy and glomerulosclerosis. The mean age of patients with stage I disease (27 ± 10.8 years) was significantly lower than those of the other stages. About 79.2%, 55%, 49.1% and 50% in stage I, II, III and IV disease respectively were asymptomatic at the time of biopsy.
Pub.: 03 Dec '15, Pinned: 25 Sep '17
Abstract: In many developing countries in the South Asian region, screening for chronic diseases in the community has shown a widely varying prevalence. However, certain geographical regions have shown a high prevalence of chronic kidney disease (CKD) of unknown etiology. This predominantly affects the young and middle-aged population with a lower socioeconomic status. Here, we describe the hotspots of CKD of undiagnosed etiology in South Asian countries including the North, Central and Eastern provinces of Sri Lanka and the coastal region of the state of Andhra Pradesh in India. Screening of these populations has revealed cases of CKD in various stages. Race has also been shown to be a factor, with a much lower prevalence of CKD in whites compared to Asians, which could be related to the known influence of ethnicity on CKD development as well as environmental factors. The difference between developed and developing nations is most stark in the realm of healthcare, which translates into CKD hotspots in many regions of South Asian countries. Additionally, the burden of CKD stage G5 remains unknown due to the lack of registry reports, poor access to healthcare and lack of an organized chronic disease management program. The population receiving various forms of renal replacement therapy has dramatically increased in the last decade due to better access to point of care, despite the disproportionate increase in nephrology manpower. In this article we will discuss the nephrology care provided in various countries in South Asia, including India, Bangladesh, Pakistan, Nepal, Bhutan, Sri Lanka and Afghanistan.
Pub.: 23 Jan '16, Pinned: 25 Sep '17
Abstract: In the last two decades, chronic kidney disease of unknown etiology (CKDu) has emerged as a significant contributor to the burden of chronic kidney disease (CKD) in rural Sri Lanka. It is characterized by the absence of identified causes for CKD. The prevalence of CKDu is 15.1-22.9% in some Sri Lankan districts, and previous research has found an association with farming occupations.A systematic literature review in Pubmed, Embase, Scopus, and Lilacs databases identified 46 eligible peer-reviewed articles and one conference abstract.Geographical mapping indicates a relationship between CKDu and agricultural irrigation water sources. Health mapping studies, human biological studies, and environment-based studies have explored possible causative agents. Most studies focused on likely causative agents related to agricultural practices, geographical distribution based on the prevalence and incidence of CKDu, and contaminants identified in drinking water. Nonetheless, the link between agrochemicals or heavy metals and CKDu remains to be established. No definitive cause for CKDu has been identified.Evidence to date suggests that the disease is related to one or more environmental agents, however pinpointing a definite cause for CKDu is challenging. It is plausible that CKDu is multifactorial. No specific guidelines or recommendations exist for treatment of CKDu, and standard management protocols for CKD apply. Changes in agricultural practices, provision of safe drinking water, and occupational safety precautions are recommended by the World Health Organization.
Pub.: 12 Jul '16, Pinned: 25 Sep '17
Abstract: The emergence of a new form of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka's North Central Province (NCP) has become a catastrophic health crisis. CKDu is characterized as slowly progressing, irreversible, and asymptomatic until late stages and, importantly, not attributed to diabetes, hypertension, or other known risk factors. It is postulated that the etiology of CKDu is multifactorial, involving genetic predisposition, nutritional and dehydration status, exposure to one or more environmental nephrotoxins, and lifestyle factors. The objective of this limited geochemical laboratory analysis was to determine the concentration of a suite of heavy metals and trace element nutrients in biological samples (human whole blood and hair) and environmental samples (drinking water, rice, soil, and freshwater fish) collected from two towns within the endemic NCP region in 2012 and 2013. This broad panel, metallomics/mineralomics approach was used to shed light on potential geochemical risk factors associated with CKDu. Based on prior literature documentation of potential nephrotoxins that may play a role in the genesis and progression of CKDu, heavy metals and fluoride were selected for analysis. The geochemical concentrations in biological and environmental media areas were quantified. Basic statistical measurements were subsequently used to compare media against applicable benchmark values, such as US soil screening levels. Cadmium, lead, and mercury were detected at concentrations exceeding US reference values in many of the biological samples, suggesting that study participants are subjected to chronic, low-level exposure to these elements. Within the limited number of environmental media samples, arsenic was determined to exceed initial risk screening and background concentration values in soil, while data collected from drinking water samples reflected the unique hydrogeochemistry of the region, including the prevalence of hard or very hard water, and fluoride, iron, manganese, sodium, and lead exceeding applicable drinking water standards in some instances. Current literature suggests that the etiology of CKDu is likely multifactorial, with no single biological or hydrogeochemical parameter directly related to disease genesis and progression. This preliminary screening identified that specific constituents may be present above levels of concern, but does not compare results against specific kidney toxicity values or cumulative risk related to a multifactorial disease process. The data collected from this limited investigation are intended to be used in the subsequent study design of a comprehensive and multifactorial etiological study of CKDu risk factors that includes sample collection, individual surveys, and laboratory analyses to more fully evaluate the potential environmental, behavioral, genetic, and lifestyle risk factors associated with CKDu.
Pub.: 07 Sep '16, Pinned: 25 Sep '17
Abstract: M Selvarajah, P Weeratunga, S Sivayoganthan, N Rathnatunga, S Rajapakse Indian Journal of Nephrology 2016 26(5):357-363 Chronic kidney disease of unknown etiology (CKDu) is a major healthcare issue in Sri Lanka. This study included 125 consecutive patients with a diagnosis of CKDu undergoing renal biopsy at one hospital from 2008 to 2012. Associations between renal outcome parameters, epidemiological data, and histopathological findings were examined and regression models constructed based on univariate associations with outcome variables as serum creatinine >1.2 and stage of CKD >3. The mean patient age was 46.21 years (standard deviation = 11.64). A marked male predominance was noted. A positive family history of CKD was seen in 35.8%. Prominent histopathological features were glomerular sclerosis (94.8%), interstitial infiltration (76%) with lymphocytic infiltration, interstitial fibrosis (71.2%), and tubular atrophy (70.4%). Importantly, significant histological changes were seen in patients with early CKDu. For CKD stage >3 independent associations were: interstitial fibrosis [P = 0.005; odds ratio (OR) =0.153] and interstitial infiltrate (P = 0.030; OR = 0.2440. For serum creatinine >1.2, independent predictors were >50% glomerular sclerosis (P = 0.041; OR = 0.92), tubular atrophy (P = 0.034; OR = 0.171, and more than 40 residential life years (P = 0.009; OR = 9.229). Chronic tubulointerstitial nephritis (TIN) appears to be the predominant histopathological finding in patients with CKDu, with significant renal pathology established early on in the course of the disease. Interstitial infiltration appears to be an independent association of advancing CKD, CKDu, histopathology, histology, and TIN.
Pub.: 29 Aug '16, Pinned: 25 Sep '17
Abstract: An epidemic of chronic kidney disease of unknown etiology (CKDu) has been occurring in Sri Lanka over the past decade, primarily among rice farming communities. The national healthcare system is struggling to address the medical needs of the growing number of affected individuals who need to be treated with dialysis and renal transplants.
Pub.: 01 May '16, Pinned: 25 Sep '17
Abstract: An alarming increase in chronic kidney disease with unknown etiology (CKDu) has recently been reported in several provinces in Sri Lanka and chronic exposures to toxic trace elements were blamed for the etiology of this disease. Keratinized matrices such as hair and nails were investigated to determine the possible link between CKDu and toxic element exposures. Elements Li, B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Ba, Hg and Pb of hair and nails of patients and age that matched healthy controls were determined with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results showed that trace element contents in the hair of patients varies in the order of Zn> Fe> Al> Mn> Cu> Ba> Sr> Ni> Pb> Cr> B> Hg> Se> Mo> Co> As> Li> Cd while Fe> Al> Zn> Ni> Cu> Mn> Cr> Ba> Sr> B> Pb> Se> Mo> Co> Hg> Li> As> Cd in nail samples. The hair As levels of 0.007 to 0.165 μg g−1 were found in CKDu subjects. However, no significant difference was observed between cases and controls. The total Se content in hair of CKDu subjects ranged from 0.043 to 0.513 μg g−1 while it was varied from 0.031 to 1.15 μg g−1 in controls. Selenium in nail samples varied from 0.037 μg g−1 to 4.10 μg g−1 in CKDu subjects and from 0.042 μg g−1 to 2.19 μg g−1 in controls. This study implies that substantial proportions of Sri Lankan population are Se deficient irrespective of gender, age and occupational exposure. Although some cutaneous manifestations were observed in patient subjects, chemical analyses of hair and nails indicated that patients were not exposed to toxic levels of arsenic or the other studied toxic elements. Therefore the early suggested causative factors such as exposure to environmental As and Cd, as suggested earlier, can be ruled out.
Pub.: 02 Aug '16, Pinned: 25 Sep '17
Abstract: Objective. To infer the influence of internal and external oxidative stress in chronic kidney disease patients of unknown etiology (CKDu) in Sri Lanka, by analyzing expression of genes related directly or indirectly to oxidative stress: glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase mu 1 (GSTM1), glucose-6-phosphate dehydrogenase (G6PD), fibroblast growth factor-23 (FGF23), and NLR family pyrin domain containing 3 (NLRP3). Methods. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was carried out for the selected populations: CKDu patients (n = 43), chronic kidney disease patients (CKD; n = 14), healthy individuals from a CKDu endemic area (GHI; n = 9), and nonendemic area (KHI; n = 16). Fold changes were quantified relative to KHI. Results. GCLC had greater than threefold upregulation in all three study groups, with a maximum of 7.27-fold upregulation in GHI (p = 0.000). GSTM1 was not expressed in 25.6% of CKDu and 42.9% of CKD patients, but CKDu patients expressing GSTM1 showed upregulation of 2.60-fold (p < 0.05). Upregulation of FGF23 and NLRP3 genes in CKD and CKDu was observed (p < 0.01), with greater fold changes in CKD. Conclusion. Results suggest higher influence of external sources of oxidative stress in CKDu, possibly owing to environmental conditions.
Pub.: 16 Dec '16, Pinned: 25 Sep '17
Abstract: In Sri Lanka, there exists chronic kidney disease of both known (CKD) and unknown etiologies (CKDu). Identification of novel biomarkers that are customized to the specific causative factors would lead to early diagnosis and clearer prognosis of the diseases. This study aimed to find genetic biomarkers in blood to distinguish and identify CKDu from CKD as well as healthy populations from CKDu endemic and non-endemic areas of Sri Lanka.The expression patterns of a selected panel of 12 potential genetic biomarkers were analyzed in blood using RT-qPCR. Fold changes of gene expressions in early and late stages of CKD and CKDu patients, and an apparently healthy population of a CKDu endemic area, Girandurukotte (GH) were calculated relative to apparently healthy volunteers from a CKDu non-endemic area, Kandy (KH) of Sri Lanka, using the comparative CT method.Significant differences were observed between KH and early stage CKDu for both the insulin-like growth factor binding protein 1 (IGFBP1; p = 0.012) and kidney injury molecule-1 (KIM1; p = 0.003) genes, and KH and late stage CKD and CKDu for the glutathione-S-transferase mu 1 (GSTM1; p < 0.05) gene. IGFBP1 and KIM1 genes showed significant difference between the early and late stage CKDu (p < 0.01). The glutamate cysteine ligase catalytic subunit (GCLC) gene had significantly different expression between KH and all the other study groups (p < 0.01). The GH group was significantly different from the KH group for the oxidative stress related genes, G6PD, GCLC and GSTM1 (p < 0.01), and also the KIM1 gene (p = 0.003). IGFBP1, insulin-like growth factor binding protein 3 (IGFBP3), fibronectin 1 (FN1) and KIM1 showed significant correlations with serum creatinine, and IGFBP1, KIM1 and kallikrein 1 (KLK1) with eGFR (p < 0.05).A panel consisting of IGFBP1, KIM1, GCLC and GSTM1 genes could be used in combination for early screening of CKDu, whereas these genes in addition with FN1, IGFBP3 and KLK1 could be used to monitor progression of CKDu. The regulation of these genes has to be studied on larger populations to validate their efficiency for further clinical use.
Pub.: 21 Jan '17, Pinned: 25 Sep '17
Abstract: Research published on Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka has been undertaken largely from biomedical and epidemiological perspectives. The main objective of these studies has been to identify the etiology of the disease, which affects as much as 15-21% of the population in some regions and is associated with kidney failure. Few studies have sought to address how CKDu is socially and behaviorally situated in the affected districts. The present study, informed by structural violence theory, utilized a mixed-method approach that analyzed primary and secondary data for Medawachchiya District Secretariat Division in Anuradhapura District for 2010 and 2015, and examined CKDu as a manifestation of social inequality and exclusion and the creation of a marginalized group of agricultural laborers. Data include historical analyses, a case-control study, ecologic analysis of features of communities and CKDu prevalence, and direct observations and interviews with people in affected communities. In 2010, the most important factor associated with CKDu was private dug wells that were used for supplying water to homes. In 2015, when the number of patients had increased, CKDu was more closely linked to occupation, especially male wage labor. The male wage laborer, being the poorest of the poor, has become a particularly vulnerable social category in agricultural settlements in Medawachchiya. The co-occurrence of this social category and CKDu can be regarded as unintended consequences of the official agricultural colonization policy that started during British colonial times and has continued since independence.
Pub.: 27 Feb '17, Pinned: 25 Sep '17
Abstract: Chronic-Kidney-Disease of Unknown-etiology (CKDu) has been reported in developing-countries like Sri-Lanka, India and Central-America without sparing the Indian sub-district (namely Canacona) located in south-Goa. The disease etiology is unlinked to common causes of diabetes and hypertension and assumed to be environmentally induced due to its asymptomatic-nature and occurrence in groundwater relying communities. This study aimed to understand environmental risk-factors underlying CKDu-etiology using Indian sub-district (Canacona) as case-study. Biochemical-analysis of CKDu-affected and non-affected individual's blood and detailed hydro-geochemical analyses of CKDu-affected and non-affected region's groundwater (drinking-water)were conducted. Trace geogenic-element-silica was highly dominant in affected-region's groundwater, thus its nephrotoxic-potential was analysed via in-vitro cytotoxicity-assays on human-kidney-cell-lines. All CKDu-affected-subjects showed increased-levels of serum-urea (52.85 mM),creatinine (941.5 μM),uric-acid (1384.5 μM), normal blood-glucose (4.65 mM), being distinct biomarkers of environmentally-induced CKD-'chronic-tubulo-interstitial-nephritis'. Affected-subjects reported high blood-lead levels (1.48 μM)suggesting direct-nephrotoxicity resulting in impaired blood-clearance and also exhibits indirect-nephrotoxicity by disrupting calcium-homeostasis causing skeletal-disorders and prolonged-consumption of NSAID's (pain-alleviation), indirectly causing renal-damage. Affected-region's groundwater was acidic (pH-5.6), resulting in borderline-lead (9.98 μgL(-1)) and high-silica (115.5 mgL(-1))contamination. Silica's bio-availability (determining its nephrotoxicity) was enhanced at groundwater's acidic-pH and Ca-Mg-deficient-composition (since these cations complex with silica reducing bioavailability). Silica exhibited renal-proximal-tubular-cytotoxicity on long-term exposure comparable with affected-region's groundwater silica-levels, by apoptosis-mediated-cell-death resulting in tubular-atrophy, interstitial-fibrosis and irreversible renal-damage (CKD). Thus this study provides novel-insights into nephrotoxic-potential of trace-geogenic-element-silica in CKDu causation. It highlights direct-indirect nephrotoxicity exhibited by lead at low-levels due to its bio-accumulative-capacity. Silica's nephrotoxic-potential can be considered when deciphering etiology of CKDu-problem in developing-countries (relying on groundwater).
Pub.: 16 Mar '17, Pinned: 25 Sep '17
Abstract: Environmental toxin/s is alleged to be the contributory factor for the chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. The potential of drinking water as a medium for the nephrotoxic agents in the affected subjects has been comprehensively discoursed in the recent past. The present study was aimed to assess the effect of replacing the habitual drinking water on the kidney function of CKDu patients residing in the North Central Province of Sri Lanka: METHODS: An interventional study was carried out to assess the disease progression rate of a CKDu population whose habitual drinking water was replaced by bottled spring water certified by Sri Lanka Standard (SLS) for a period of 18 month along with a population of CKDu patients who continued with their usual drinking water. Kidney function of subjects in both groups were monitored in terms of blood pressure, serum creatinine, serum calcium, serum phosphorus, hemoglobin, estimated glomerular filtration rate and urinary protein at 6 months intervals during the intervention and follow up periods.Diminished disease progression rate was observed in CKDu patients in the intervention group when compared with the non- intervention group based on serum creatinine, Hb, estimated glomerular filtration rate and urinary protein levels. Extensive interventional studies are required to generalize effect of drinking water on CKDu population.The habitual drinking water is likely to be a contributory factor towards the progression of the disease.
Pub.: 04 Apr '17, Pinned: 25 Sep '17
Abstract: Chronic kidney disease of unknown aetiology (CKDu) is prevalent in the North Central Province (NCP) of Sri Lanka and ingestion of dug well water is considered a potential causative factor. Three CKDu prevalent villages were selected from the NCP based on the number of CKDu patients in the locality.Forty Wistar rats were divided into four groups with 10 rats each. Group No 1, 2 and 3 were given water from selected dug wells. Control group was given tap water from Colombo. Water samples were analysed for fluoride, iron, arsenic, cadmium and calcium. Histopathological examination of liver and kidney tissues were performed.Significant reduction of glomerular filtration rate (GFR) was observed in two test groups compared to the control group (p0.05). In one group hepatocellular carcinoma with elevated serum liver enzymes was observed whilst hepatitis was observed in another test group (p<0.05). But mixed lesions were common in all affected rats. Significantly high renal tubular lesion index was observed in all three experimental groups (p<0.05) and high glomerular lesion index (p=0.017) was observed in one test group. Cadmium, arsenic and iron contents were below detectable levels in the NCP water sources and tap water from Colombo.Different wells may have different concentrations of environmental toxins and depending on the severity of the toxin contents GFR and grade and type of liver and kidney lesions may vary. High fluoride and other undetected toxins in shallow dug wells may be the causative factors for renal and liver lesions in these Wistar rats.
Pub.: 10 Apr '17, Pinned: 25 Sep '17
Abstract: The main causes of chronic kidney disease (CKD) globally are diabetes and hypertension but epidemics of chronic kidney disease of unknown etiology (CKDu) occur in Central America, Sri Lanka, India and beyond. Althoug also being observed in women, CKDu concentrates among men in agricultural sectors. Therefore, suspicions fell initially on pesticide exposure, but currently chronic heat stress and dehydration are considered key etiologic factors. Responding to persistent community and scientific concerns about the role of pesticides, we performed a systematic review of epidemiologic studies that addressed associations between any indicator of pesticide exposure and any outcome measure of CKD. Of the 21 analytical studies we identified, seven were categorized as with low, ten with medium and four with relatively high explanation value. Thirteen (62%) studies reported one or more positive associations, but four had a low explanation value and three presented equivocal results. The main limitations of both positive and negative studies were unspecific and unquantified exposure measurement ('pesticides'), the cross-sectional nature of most studies, confounding and selection bias. The four studies with stronger designs and better exposure assessment (from Sri Lanka, India and USA) all showed exposure-responses or clear associations, but for different pesticides in each study, and three of these studies were conducted in areas without CKDu epidemics. No study investigated interactions between pesticides and other concommittant exposures in agricultural occupations, in particular heat stress and dehydration. In conclusion, existing studies provide scarce evidence for an association between pesticides and regional CKDu epidemics but, given the poor pesticide exposure assessment in the majority, a role of nephrotoxic agrochemicals cannot be conclusively discarded. Future research should procure assessment of lifetime exposures to relevant specific pesticides and enough power to look into interactions with other major risk factors, in particular heat stress.
Pub.: 26 May '17, Pinned: 25 Sep '17
Join Sparrho today to stay on top of science
Discover, organise and share research that matters to you