Cytogenotoxicity of drinking water of selected dug wells in an area where chronic kidney disease of unknown aetiology is prevalent in Sri Lanka

Consumption of contaminated groundwater is implicated as a risk factor for chronic kidney disease of unknown aetiology (CKDu), which is a public health problem in some tropical countries, including Sri Lanka. However, the application of bioanalytical tools to assess the potential toxicity of groundwater consumed by CKDu-affected communities has received limited attention.  This study explored for the first time the potential cytogenotoxic risk of drinking water from selected dug wells in a CKDu endemic area in Sri Lanka using in vivo bioassays (Cyprinus carpio erythrocyte-based and Allium cepa root meristem-based tests), complementary to physicochemical analysis. In dug well water used by households with CKDu, fluoride levels in dry and rainy periods, and electrical conductivity, alkalinity, and total hardness levels in the dry period were significantly higher than the well water used by households with no CKDu cases in the same endemic area. Exposure to water of dug wells used by households with CKDu triggered nuclear buds and fragmented nuclei induction in fish erythrocytes and mitosis suppression and induction of condensed nuclei and binuclei in root meristems in most cases. Kidneys of fish exposed to dug well water exhibited renal tubular degeneration. Bioassays revealed cytogenotoxicity of dug well water, which may be due to interactive toxicity of contaminant mixtures including fluoride and other unknown toxicants. Untreated water from such dug wells may pose cytogenotoxic risks to the consumers, influencing disease progression.