The introduction of elevated amounts of foreign ions into the blood may lead to impairment of the filtration membrane of kidneys and chronic kidney damage. In order to assess the risk of consumption of drinking water (dug well water) in chronic kidney disease of unknown etiology (CKDu), affected areas in Sri Lanka, trace metals, and other counterions in water samples obtained from dug wells were analyzed and compared with a reference area. Drinking water could be the major source that is responsible for entering nephrotoxic ion contaminants into the human body. To achieve the objective, drinking water samples were collected from dug wells in two CKDu endemic areas and a reference area where no CKDu patients were found in a dry season. In the Wewelketiya area (one of the endemic areas), Cd concentrations in 60% of water samples and Pb concentrations in 40% of water samples have exceeded the maximum limit given by Sri Lanka water quality standards. Fluoride concentrations also have exceeded the permissible limits of more than 80% of collected water samples in both CKDu endemic areas. However, none of the water samples in reference areas has reported that Cd, Pb, and fluoride are beyond their maximum permissible limits. Hence, people in the particular CKDu endemic areas are at risk of kidney tissue damage due to long-term exposure to drinking water with elevated levels of some metal ions and counterions.

中文翻译：

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通过分析饮用水中的金属离子和反离子污染物，探索病因不明的慢性肾脏病 (CKDu) 的根本原因：斯里兰卡的一项研究

将大量外来离子引入血液可能会导致肾脏滤过膜受损和慢性肾脏损伤。为评估慢性肾病病因不明（CKDu）饮用饮用水（挖井水）的风险，对斯里兰卡受影响地区，对挖井水样中的微量金属和其他反离子进行分析比较带参考区域。饮用水可能是导致肾毒性离子污染物进入人体的主要来源。为实现该目标，在旱季未发现CKDu患者的两个CKDu流行区和一个参考区的挖井中采集饮用水样品。在 Wewelketiya 地区（流行地区之一），60%的水样中的Cd浓度和40%的水样中的Pb浓度超过了斯里兰卡水质标准给出的最高限值。在两个 CKDu 流行区收集的水样中，氟化物浓度也超过了 80% 以上的允许限值。然而，参考区域的水样均未报告 Cd、Pb 和氟化物超出其最大允许限值。因此，由于长期接触某些金属离子和反离子水平升高的饮用水，特定 CKDu 流行地区的人们面临肾组织损伤的风险。在两个 CKDu 流行区收集的水样中，氟化物浓度也超过了 80% 以上的允许限值。然而，参考区域的水样均未报告 Cd、Pb 和氟化物超出其最大允许限值。因此，由于长期接触某些金属离子和反离子水平升高的饮用水，特定 CKDu 流行地区的人们面临肾组织损伤的风险。在两个 CKDu 流行区收集的水样中，氟化物浓度也超过了 80% 以上的允许限值。然而，参考区域的水样均未报告 Cd、Pb 和氟化物超出其最大允许限值。因此，由于长期接触某些金属离子和反离子水平升高的饮用水，特定 CKDu 流行地区的人们面临肾组织损伤的风险。