Assessment of Heavy Metals in Shallow Aquifer Boreholes and Possible Links to Chronic Kidney Disease (CKD) In Maiduguri and Environs, Borno State, Nigeria

Abstract

Groundwater contamination by heavy metals is a global environmental and public health concern. In Maiduguri and environs, northeastern Nigeria,
groundwater from the shallow unconfined aquifer is the principal source of drinking water and is highly vulnerable to pollution due to poor sanitation and waste disposal practices in the area. This study assessed heavy metal concentrations in groundwater from 300 shallow aquifer boreholes to evaluate potential health risks, particularly in relation to Chronic Kidney Disease (CKD). Water samples were collected during a 2022 field campaign and analysed for Mercury (Hg), Copper (Cu), Arsenic (As), Cadmium (Cd), Lead (Pb), and Chromium (Cr) using Atomic Absorption Spectrophotometry (AAS, Buck Scientific 210 VGP) following APHA standard methods. Results show that Hg concentrations were below both World Health Organization (WHO) and Nigerian Standards for Drinking Water Quality (NSDWQ) guideline values in all the borehole samples. Cu concentrations exceeded the WHO and NSDWQ in only one borehole sample. Thus, the level of Hg and Cu concentrations in the borehole samples do not appear to pose health concern. However, the concentrations of As, Cd, Pb and Cr in the borehole samples show variable percentages above the WHO/NSDWQ guideline from As-18%; Cd-23%; Pb-48%; and Cr-56%. These indicate significant health risks from exposure to these metals, because Pb and Cd are known nephrotoxicants, while As and Cr (particularly hexavalent
chromium) have been reported to have links to kidney diseases. Therefore, consumption of water from these boreholes with elevated As, Cd, Pb and Cr may contribute to long-term adverse health outcomes, including increased CKD risk. Mitigation measures may include: implementing appropriate water treatment technologies on the affected boreholes; use of alternative treated surface water; and drilling to deeper aquifers free from these contaminants. In addition, there is the need to strengthen waste management practices, continuous groundwater monitoring and public education campaigns, which can reduce exposure to these risks and safeguard community health.