Environmental and occupational exposures for chronic kidney disease of unknown aetiology (CKDu): field investigations in rural Sri Lanka

Chronic kidney disease of unknown aetiology (CKDu) is a public health concern, with a male predominance in rural agricultural communities in Sri Lanka. This cross-sectional field study investigated environmental and occupational exposures potentially contributing to CKDu prevalence in rural villages. Field observations and informal conversations with villagers were used to record potential exposures in situ and contextualise how they interacted in daily life. Based on CKDu occurrence in Kandy Teaching Hospital renal biopsy data, 12 villages in Matale and Badulla Districts with variable CKDu occurrence were included. Field observations documented housing conditions, drinking water sources, agricultural activities, and other potential exposures. Unstructured conversations with villagers provided information on less observable exposures, including temporal changes in drinking water supply. Local government offices provided information on village occupations and registered chronic kidney disease (CKD) patients. Agrochemical handling was performed almost exclusively by men and, particularly in paddy fields, often without personal protective equipment (PPE), despite reported use by farmers. Consistent use of improved water sources, such as reverse osmosis filters, was hindered by cost, limited availability and travel time, leading to continued use of well water. Villages with higher estimated CKD prevalence were characterised by greater dependence on agriculture, agrochemical use without adequate PPE and limited access to improved drinking water. This study indicates that exposure measurement for CKDu research should better capture PPE use and drinking water-source use. Structured questionnaires on the primary drinking water source may not capture multiple water-source use. Similarly, closed-ended questions on PPE use may not reflect actual practice unless researchers and farmers share a clear understanding of what constitutes PPE. The finding that men almost exclusively applied agrochemicals may help explain the male predominance of CKDu and warrants further investigation.