Glyphosate and Fluoride in High-Hardness Drinking Water Are Positively Associated with Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka

Chronic kidney disease of uncertain etiology (CKDu) has emerged as a serious public health concern in farming communities globally, especially in Sri Lanka with 5%-20% of the adult population affected by the disease in CKDu-endemic regions. It is hypothesized that drinking water contamination of glyphosate in combination with water hardness and co-occurring trace elements contribute to CKDu in Sri Lanka. However, no studies to date have comprehensively examined this hypothesis. Here, we conducted a large field study to measure and compare drinking water chemical burden in CKDu-endemic areas with CKDu-nonendemic areas in rural Sri Lanka. Chemical measures of water quality included glyphosate, water hardness, and trace elements, including fluoride. Glyphosate was detected in 44% of endemic wells and 8% of nonendemic wells. Fluoride was detected in 99% of endemic wells and 80% of nonendemic wells. Logistic regression revealed that the presence of elevated glyphosate, fluoride, hardness, and vanadium in wells was positively associated with CKDu prevalence. The co-occurrence of glyphosate and high hardness indicate potential complexation of glyphosate in wells from CKDu-endemic areas. Collectively, our work represents the first definitive assessment of glyphosate presence in regions with geogenic high water hardness and fluoride and demonstrates a strong correlation with CKDu incidence.

Automated summary

Chronic kidney disease of uncertain etiology (CKDu) is a serious public health concern in farming communities, particularly in Sri Lanka. This study found that glyphosate, water hardness, and trace elements, including fluoride, in drinking water were associated with CKDu prevalence. The presence of elevated levels of glyphosate, fluoride, hardness, and vanadium in wells was positively correlated with CKDu incidence.