Assessment of Heavy Metal Contamination and Human Exposure Risk in Drinking Water Sources of Gaidau Community, Sokoto, Northwestern Nigeria

The term 'heavy metals' refers to a class of elements characterized by high density and significant toxicity, even at minimal concentrations. The contamination of water resources with these metals has become a pronounced environmental problem of critical importance. Heavy metals are introduced into aquatic systems from a multitude of sources, which encompass industrial effluent, runoff from agricultural lands, substandard waste management practices, and natural geological phenomena. Upon entering a water supply, these metallic elements can demonstrate remarkable persistence over extended durations, thereby presenting substantial hazards to both human populations and the broader ecosystem. Certain demographic groups, specifically children and expectant mothers, exhibit heightened vulnerability to the effects of these metals and face an elevated risk of developmental complications. The presence of heavy metals such as lead, mercury, cadmium, and arsenic in water supplies is linked to severe health conditions, including but not limited to neurological impairment, renal failure, and various forms of cancer. In the Gaidau Community, located in Sokoto, Nigeria, residents are confronted with considerable health threats stemming from the contamination of their water sources by heavy metals. This investigation was designed to quantify the concentration levels and ascertain the human exposure risk associated with specific heavy metals—namely cadmium (Cd), copper (Cu), nickel (Ni), iron (Fe), and zinc (Zn)—within the drinking water of the Gaidau Community. The community has undergone swift modernization, a process that has amplified concerns regarding the potential for metallic contamination of its local water bodies. Although initial observations suggested the presence of potentially hazardous concentrations of heavy metals, the precise degree of exposure among the local populace has not been systematically recorded, which complicates the formulation of effective remediation plans. This research endeavors to conduct a methodical evaluation of heavy metal levels in Gaidau's water supply. It utilizes sophisticated monitoring approaches, including wastewater-based epidemiology (WBE), to quantify population-wide exposure and establish a robust scientific foundation for future public health initiatives. A descriptive cross-sectional study framework was adopted to evaluate the existing contamination levels in a variety of water sources, including boreholes, local wells, and streams, within the Gaidau Community. Water specimens were procured from these designated sources and subjected to analysis via Atomic Absorption Spectrophotometry (AAS) at the Chemistry Department of Ahmadu Bello University, Zaria. The analytical results consistently demonstrated that streams contained the most elevated concentrations of the targeted heavy metals, followed in descending order by wells and then boreholes. Specifically, cadmium concentrations in stream water (mg/L) surpassed the levels found in well water ( mg/L) and borehole water ( mg/L). Copper concentrations reached their peak in streams (mg/L), while nickel levels in streams ( mg/L) were markedly higher than those recorded in wells ( mg/L) and boreholes ( mg/L). Iron concentrations were also substantially higher in streams (mg/L) when compared to wells ( mg/L) and boreholes ( mg/L). A similar distribution was observed for zinc, with its highest concentration (mg/L) also found in stream water. This investigation highlights a significant degree of heavy metal contamination across the water sources available to the Gaidau Community, with streams being the most affected, thereby posing substantial health risks to the inhabitants. The outcomes of this study strongly indicate the necessity for focused public health interventions aimed at curtailing exposure to heavy metals and alleviating the associated health dangers.