Risk attribution for chronic kidney disease of unknown etiology (CKDu) with cyanotoxin exposure

The study assessed the cyanotoxin exposure risk for chronic kidney disease of unknown etiology (CKDu) via drinking water, analyzing microcystins (MCs), nodularin (NOD), and cylindrospermopsin (CYN). In two CKDu endemic areas, Girandurukotte and Dehiattakandiya, Sri Lanka, 154 water samples were collected along with 38 from a CKDu non-endemic area, Sewanagala, Sri Lanka. Cyanotoxins were detected using high-performance liquid chromatography (HPLC). MCs were found in 24.3% of CKDu, 17.0% of CKD and 31.7% of Healthy individuals’ well waters in the CKDu endemic areas, with 26.8% of Healthy individuals’ in the non-endemic area. About 93% of water samples exceeded the World Health Organization (WHO) guideline value for MCs in drinking water (1 µg/L). For CYN, the prevalence was 46.6% of CKDu, 19.6% of CKD, 23.2% of Healthy individuals’ in the CKDu endemic areas and 10.7% of Healthy individuals’ in the non-endemic area. The CYN mean concentration in CKDu well waters was approximately five-fold higher compared to the non-endemic area (ANOVA, p = 0.04). No association was observed between cyanotoxin prevalence in well waters and health status of being CKDu, CKD or Healthy. Most (35.7%) of CKDu individuals exceeded the WHO-recommended tolerable daily intake value (0.03 µg/kg bw/d) for CYN. NOD was not detected in any water sample. Prolonged exposure to MCs and CYN in drinking water may increase stress and weaken the kidneys, rendering it a potential risk factor for CKDu.