Comparative analysis of drinking water quality in a CKDu endemic area versus a reference area in Sri Lanka: a topographic perspective

Chronic kidney disease of unknown cause (CKDu) is a serious health issue affecting Sri Lanka's farming communities. Continuous assessment of physico-chemical parameters and trace metals in drinking water sources is crucial for exploring the root cause of CKDu. This study investigates how geographical distribution affects trace metal and fluoride contamination in CKDu endemic Naminigama Grama Niladhari Division (GND) and Sulugune GND (reference area) in the same Divisional Secretariat (DS). Preliminary analysis indicates that trace elements, major elements, and fluoride concentrations of drinking water are within Sri Lanka’s water quality guidelines in both areas. However, long-term exposure to metals may generate risks. This study analysed well water samples from these sites for trace elements (cadmium, lead, chromium, arsenic, zinc, copper, iron) and major elements (sodium, potassium, aluminum) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Additionally, fluoride, magnesium, and calcium levels were measured. Pb, Cd, As, and Cr were within permissible limits according to Sri Lankan water quality guidelines in both areas. However, aluminum levels exceeded limits in both areas. Statistical analysis showed significantly higher concentrations of Na, Mg, Ca, Zn, Cr, As, and Cd in Naminigama than the reference area. In Naminigama, agricultural fields are at higher elevations compared to residential areas, whereas opposite in Sulugune. The metal distribution variation may be due to the geographical condition of the reference area, where surface runoff attenuates agricultural waste, thereby reducing contamination of its drinking water sources. These findings suggest that topography plays a crucial role in water contamination, providing insights into improved water quality management.