Assessing the link between groundwater quality and kidney failure of unknown aetiology in Belgium

Chronic kidney disease (CKD) is a global public health problem as it represents a major risk factor for accelerated cardiovascular disease and premature ageing. CKD may progress to kidney failure (KF) that can lead to death. Over the last decades, case series of CKD have emerged among agricultural workers in developing countries. The cause of this epidemic remains unknown, and the disease was consequently named CKD of unknown aetiology (CKDu). Several arguments lead to think that CKDu is linked to the exposition to environmental toxicants. Additionally, a recent study, in 2020, pointed out a high incidence of unexplained KF (KFu) in agricultural regions in California expanding the problem of CKDu to developed countries. In Belgium, on average for 20% of patients with KF no known causes were identified. For those patients, the presence of toxicants could have had adverse effects on their kidneys. In a retrospective epidemiological study, we combined data from more than 30,000 incident patients with KF and concentrations of 17 pollutants collected in groundwater bodies in Belgium (1 million samples) over a 15-year period to assess potential associations between environmental factors and incidence of KFu. Using this large dataset, we identified hotspots of KFu in the west of Belgium, with a significantly higher incidence of KFu compared to the rest of Belgium. In those hotspots of KFu, we uncovered higher groundwater concentrations of fluoride and TM (arsenic, chrome, mercury and lead) and a higher prevalence of levels above the national median, as compared to the rest of Belgium. We concluded that the presence of higher concentration of TM and fluoride in groundwater of those regions, as the result of heavy application of fertilisers, could have had adverse effects on their kidneys.