Abstract
Heavy metals (HMs) were originally formed in the universe long before human evolution and are now ubiquitous in the environment, where some HMs are good as essential elements for human health while others are not. The purpose of this analytical review is to provide an updated clinical overview on health risks attributable to drinking water containing specific HMs and to discuss new aspects of molecular steps leading to disrupted diseases. This approach was favored because the study cohorts were homogeneous, since exposed individuals lived in households where all members had access to the same drinking water of constant quality. Among the HMs under consideration, aluminum, arsenic, cadmium, chromium, copper, iron, lead, manganese, and mercury were detected in drinking water and represented a health risk if levels were above thresholds recommended by national and international regulatory authorities. For example, (1) aluminum increased the risk of dementia and Alzheimer's disease; (2) arsenic was associated with the development of bladder cancer; (3) cadmium increased the no-carcinogenic, as well as the carcinogenic, health risk; (4) chromium was considered as a risk factor for liver and kidney injury, as well cancer development; (5) copper contributed to cognitive impairment in the aging population and Alzheimer's disease; (6) iron increased the non-carcinogenic health risk; (7) lead impaired neurodevelopmental functions in children; (8) manganese increased the risk of attention-deficit hyperactivity disorder (ADHD); and (9) mercury was causally related to chronic kidney disease. In contrast, for nickel and zinc, no overt health risks have been reported, likely due to low levels in the drinking water, attributable to their low water solubility. Of note is the good news that some HMs represent essential elements for human health. In essence, many HMs were detected in drinking water and exerted non-carcinogenic or carcinogenetic health risks, requiring proactive management of national and international regulatory authorities.