EFFECT OF WATER HARDNESS ON NON-COMMUNICABLE DISEASES, INCLUDING CHRONIC KIDNEY DISEASE OF MULTIFACTORIAL ORIGIN (CKDMFO/CKDUO)

Environmental pollution, including air and water contamination, causes or aggravates many acute and chronic human diseases. Although scientific literature prior to the last decade showed some associations between hardness/softness of water with cardiovascular diseases, recent data do not support this proposition. Previously postulated associations were derived from the data generated from observations and uncontrolled epidemiological and cohort studies, the results of which have not been confirmed. It was claimed that consumption of soft water increased cardiovascular diseases whereas hard water decreased them. Critical evaluation of recent data support neither of these claims. Recently, an association between drinking hard water (or ionicity) and chronic kidney disease of multifactorial origin (CKDmfo/CKDuo) has been proposed but disputed by others. CKDmfo/CKDuo is prevalent in dry-zonal, agriculture-based tropical countries, including Sri Lanka. Most regions affected by CKDmfo had hard water for centuries, but this disease has manifested only during the past few decades. However, during the past four decades, there had been several key changes in these agricultural regions, such as the increased use of agrochemicals associated with the green revolution, environmental pollution, and human behavioral changes including abandoning traditional agricultural methods and unhealthful food habits. Despite the absence of scientific data, few claim that CKDmfo is caused by the hypothetical complexes of pesticides, heavy metals, and hard water. Even if such complexes are formed, these components are insoluble in water and highly unlikely to be absorbed through the gastrointestinal tract. Apart from the well-known association of the consumption of hard water and chronic dehydration with urinary stones, there are no other scientifically established associations of water hardness with human diseases. Considering the pathophysiology and after a detailed review of published literature, the author concludes there is no confirmatory scientific evidence to support these hypotheses.