Chronic kidney disease (CKD) affects ~15% of the population globally. However, in recent years kidney disease with an unknown etiology (i.e. CDKu) has emerged in rural farming communities in Mesoamerica and South Asia, including in Sri Lanka, where 5-20% of the adult population are affected by the disease. It is hypothesized that the pesticide glyphosate in combination with water hardness and heavy metals is a primary driving factor for CKDu prevalence in Sri Lanka. No studies to date have examined the relationship between drinking water concentrations of glyphosate, water hardness, and heavy metals and CKDu occurrence in rural Sri Lanka, although previous research has demonstrated glyphosate-heavy metal mixtures may cause kidney toxicity. We have conducted an exploratory study to assess concentrations of glyphosate, heavy metals, and hardness in drinking water wells in areas of Sri Lanka with endemic CKDu and those without significant CKDu incidence. Eighteen wells were sampled with 12 CKDu-endemic wells and 6 non-CKDu wells. A novel mixed-mode LC-MS/MS method was used to quantify glyphosate (and its degradation product AMPA) levels in water. ICP-MS was used to quantify 12 heavy metals and water hardness measurements were acquired using a calmagite colorimetric method. Mann-Whitney U-Tests, logistic regressions, and multiple analyses were performed on statistically relevant variables. Results indicated that 100% of CKDu-endemic wells had detectable levels of glyphosate (0.26 µg L^-1 – 3.67 µg L^-1), while 100% of non-CKDu wells had glyphosate levels below the quantitation limit of the method (LOQ = 0.75 µg L^-1). Hardness measurements demonstrated that CKDu-endemic wells had statistically significant differences in calcium hardness levels relative to non-CKDu wells, i.e. 80.6 mg mL^-1 of CaCO₃ compared to 44.8 mg mL^-1 of CaCO₃. ⁵¹V, ⁵⁶Fe, ⁵⁵Mn, ⁶⁰Ni, and ⁷⁵As were detected in both classes of wells, but no differences were statistically significant. Our results indicate that there is a significant correlation (R = 0.61) between glyphosate and hardness levels in wells with respect to CKDu incidence in rural Sri Lanka. Work is ongoing to examine a larger cohort of 200 wells in rural Sri Lanka to further explore associations between drinking water exposure and CKDu.

P. Mangala De Silva

Appearances