Drinking water quality and chronic kidney disease of unknown etiology (CKDu): synergic effects of fluoride, cadmium and hardness of water

Abstract

High prevalence of chronic kidney disease of unknown etiology (CKDu) in some regions of the world is suspected mainly due to a toxin-mediated renal failure. We examined the incidence of CKDu and potable chemical water quality in a CKDu-affected region. This region has been identified as a high-risk zone for CKDu (location: latitude: 8.3500°-9.0000°, longitude: 80.3833°-81.3000°, North Central Province, NCP, Sri Lanka) by the World Health Organization (WHO). However, within this macro-region, small pockets of CKDu non-prevalence zones do exist; notably, the residents in those pockets consume spring water. Therefore, the drinking water quality of four areas, namely high-CKDu-prevalence areas (zone I), low-CKDu-prevalence area (zone II), the CKDu-free isolated pockets (zone III) and control areas (controls) were examined for F, Al, Cd, and As, and hardness and the statistical analysis were carried out to probe possible correlations among these parameters. The fluoride and hardness concentrations of water in zone III and control areas are much lower compared to zones I and II, and the water hardness is ~61 mg/L CaCO3. In zones I and II, the harness of drinking water is ~121-180 mg/L CaCO3; however, Al, Cd and As concentrations are almost comparable and below WHO recommendations. In most of the locations in zones I and II, the F concentration in drinking water is higher than the WHO recommendations. The peculiar distribution patterns of CKDu point to a synergic effect of trace elements in water for etiology of the disease.

Endemic Nephropathy Around the World

“…suggested that hard water could enhance the cytotoxic properties of fluoride 79 . Undeniably, fluoride levels in drinking water from endemic regions are above WHO safe levels for tropical countries80, 81; however, adjoining farms have not seen significant CKD u 82 . Other theories include the formation of fluoro-aluminium complexes when boiling fluoride-rich water in aluminum kettles (often constructed from discarded car engines).…”

Upregulation of Oxidative Stress Related Genes in a Chronic Kidney Disease Attributed to Specific Geographical Locations of Sri Lanka

“…Studies have analyzed the amount of trace and ultra trace elements in drinking water and have found moderate to high levels of fluoride in affected regions [29]. Wasana et al [30] found strong relation between synergistic effects of fluorine, cadmium, and hardness of drinking water and prevalence of CKDu. Dharma-wardana et al [31] hypothesize that CKDu in the NCP is linked with fertilizer runoff into the river systems from agricultural activity in the central hills which increases the ionicity of the drinking water which has potential to further damage the protein structures in the kidney.…”

Removal of fluoride from aqueous solution by porous Vaterite calcium carbonate nanoparticles

“…This shows that there is some correlation between fluoride in drinking waters and the occurrence of CKDU. However, there are no evidence to confirm that fluoride alone is causing CKDU except that two reports showing excess fluoride and calcium together damaging kidneys of laboratory mice [40].…”