K. OJEAGA

This study assessed the human health risks associated with heavy metals in groundwater from Oluku, Edo State, Nigeria, with a focus on dermal exposure. Groundwater, a primary domestic water source, is vulnerable to contamination by both natural and anthropogenic activities, including industrial discharge, agricultural runoff, and improper waste disposal. Key heavy metals analyzed included zinc (Zn), cadmium (Cd), manganese (Mn), iron (Fe), and Lead (Pb). Fifteen groundwater samples were collected and analyzed using atomic absorption spectrometry (AAS) following standard procedures. Concentrations were compared against World Health Organization (WHO, 2017) and Nigerian Standard for Drinking Water Quality (NSDWQ, 2007) limits, while potential human health risks were estimated using the United States Environmental Protection Agency (USEPA, 2004) Human Health Risk Assessment (HHRA) framework. Results indicated that zinc (Zn) and iron (Fe) were present at relatively higher levels, with mean concentrations of 3.05 mg/L and 1.53 mg/L, respectively, while lead (Pb) and cadmium (Cd) recorded concentrations of 0.604 mg/L and 0.462 mg/L, exceeding WHO and NSDWQ limits. Chronic Daily Intake (CDI) and Hazard Quotient (HQ) analyses revealed that non-carcinogenic risks from Zn, Fe, and Mn were minimal. However, Pb and Cd posed significant health risks, particularly for children, who exhibited higher exposure levels due to lower body weight and greater dermal contact. Carcinogenic risk assessment further indicated that both Pb and Cd exceeded acceptable USEPA limits, with cadmium presenting the highest lifetime cancer risk. The study concluded that Fe and Zn likely originated from natural geogenic sources within the Benin Formation, while Pb and Cd contamination was predominantly anthropogenic, linked to industrial, domestic, and agricultural activities. The uneven spatial distribution of metals highlighted the influence of proximity to pollution sources. These findings underscore the urgent need for continuous groundwater monitoring, effective waste management, and public health interventions to mitigate exposure risks in Oluku, ensuring the safety of groundwater resources for domestic use.

This study was conducted to investigate the reservoir quality of outcropping sediments in the Lokoja Basange Formation, which is located in the Anambra Basin and specifically determine sieve analysis and characterize the reservoir qualities of the sediments by inferring the porosity of the Lokoja Basange Formation. A total of fourteen (10) samples were collected and analyzed for the study. Freshly obtained samples for sieve analysis were systematically retrieved from different layers on each outcrop in the study area. The reservoir porosity and permeability of the sandstone units of the Lokoja Formations were estimated from sieve analysis. The predictive tools for the determination of reservoir quality of the outcropping sediments in Lokoja Basange which are porosity and textural characteristics and textural parameters of the sediments. The result showed that the mean size of sediments in all ten locations from the area of study ranges from 2.94 - 4.03mm. The highest mean was observed at L9, while the lowest mean was observed in L14. The results from Table 4.11 also showed that at locations L9, L10, L11, L12, and L13, the sediments exhibit coarse characteristics, as indicated by their relatively higher grain sizes, which exceed 2mm. The result showed that the porosity values across all locations are consistent (0.255), indicating that regardless of the variations in grain size distribution, the overall volume of void space within the sediment remains the same. It is recommended that further studies be carried out on this basin so as to determine the provenance of the sediments.

This study assessed heavy metal contamination and associated health risks in soils around a sand mining site in Ikpeshi, Edo State, Nigeria. Soil samples were collected at varying distances from the mine and analyzed for Fe, Zn, Cu, Pb, Cd, Mn, Ni, Cr, and Co. Results showed that most metals were below U.S. EPA limits, except Cobalt (Co). Pollution indices indicated low contamination levels overall, though Cadmium (Cd) showed moderate contamination linked to mining activities. The ecological risk index (RI = 79.11) revealed low ecological threat. Health risk assessment found negligible non-carcinogenic effects, while the Total Carcinogenic Risk (TCR) from Pb, Cd, Ni, and Cr was within the U.S. EPA acceptable range (10⁻⁶ to 10⁻⁴) for both adults and children. However, Cd and Cr contributed most to potential cancer risk. Continuous monitoring and stricter mining regulations are recommended to prevent future health hazards.

This study provides a comprehensive analysis of groundwater flow direction in Iyuku, Auchi, offering valuable insights into hydrogeological conditions and the factors influencing groundwater movement. The wells were chosen to ensure spatial coverage of different geological formations and topographical variations. Key parameters such as hydraulic head, ground surface elevation, and static water level were measured using a Global Positioning System (GPS) device and a dip meter. The hydraulic head was calculated by subtracting the water table depth from the surface elevation, providing insights into groundwater movement. A total number of ten (10) hydraulic head values were analyzed which ranges from 121.92 to 297.882. The collected data were processed using ArcGIS 10.8 software, which was utilized to generate a potentiometric surface map indicating groundwater flow direction. The GIS-based methodology allowed for precise mapping and visualization of the spatial distribution of groundwater movement within the study area. The results of the study revealed that groundwater in Iyuku, Auchi, predominantly flows from the northeastern region toward the southwestern region. This flow pattern is driven by variations in hydraulic head, which is influenced by factors such as topography, geological formations, and groundwater recharge and discharge zones. The presence of fractured basement rocks and
sedimentary deposits in the area plays a crucial role in groundwater movement by creating pathways for water infiltration and flow. Furthermore, the study identified that unregulated human activities, such as improper waste disposal, sewage leaks, and agricultural runoff.

Groundwater serves as a vital source of drinking water for millions worldwide, particularly in regions with limited access to treated surface water. However, its quality is increasingly compromised by contamination from heavy metals (HMs), which originate from both geogenic and anthropogenic sources. These metals pose significant non-carcinogenic health risks due to their persistence, bioaccumulation, and toxicity even at trace concentrations. This study evaluates the non-carcinogenic health risks associated with the ingestion of groundwater contaminated by heavy metals in the selected study area. Concentrations of key heavy metals including arsenic (As), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), and zinc (Zn) were determined using standard analytical techniques. Spatial distribution patterns were analyzed to identify contamination hotspots. Health risk assessments were conducted for both children and adults using established models that calculate hazard quotients (HQ) and hazard indices (HI). The findings reveal varying degrees of exposure risk across age groups and sampling locations, underscoring the urgent need for targeted public health interventions and sustainable groundwater management strategies. This research contributes valuable data to environmental health science and supports policy development aimed at mitigating heavy metal exposure through ingestion pathways.

The study assessed the levels of heavy metals in soils near sand mining sites in Iyuku, Auchi, Edo State, Nigeria and evaluated associated non-carcinogenic health risks through incidental ingestion. Soil samples were collected from ten locations, air-dried, sieved and analyzed for Fe, Zn, Cu, Pb, Cd, Mn, Ni, Cr and Co using atomic absorption spectrophotometry after aqua regia digestion. Mean concentrations were highest for Fe (56.24 mg/kg), followed by Zn (27.15 mg/kg) and Cu (18.76 mg/kg), with Cd and Co at trace levels (0.45 mg/kg and 0.32 mg/kg, respectively). All values fell below World Health Organization (WHO, 2011) and United State Environmental Protection Agency (USEPA, 1992) soil quality guidelines, indicating limited contamination. Chronic daily intake (CDI) via ingestion was calculated for children and adults, revealing higher exposure in children due to behavioural factors. Hazard quotients (HQ) for individual metals and the hazard index (HI) for combined exposure were all below 1, suggesting negligible non-carcinogenic risks. However, elevated Fe and Zn near active pits highlight the need for ongoing monitoring. The findings underscore the importance of regulatory measures to prevent future escalation of risks in similar mining communities, emphasizing sustainable practices to protect vulnerable groups.

The research evaluates the potential health hazards arising from the inhalation of dust contaminated with heavy metals emitted during sand mining operations in Jattu, Auchi, Edo State, Nigeria. Ten surface soil samples were systematically collected
from active mining sites and analyzed for Fe, Zn, Cu, Pb, Cd, Mn, Ni, Cr and Co using Atomic Absorption Spectrophotometry following aqua regia digestion. The results revealed that Fe (52.619mg/kg), Zn (25.586mg/kg), and Cu (21.978mg/kg) were the most abundant metals, while Cd (0.731mg/kg) and Co (2.39mg/kg) occurred in lower concentrations, with all measured values below (WHO, 2010) and (USEPA, 2001) permissible limits, indicating moderate contamination. Risk assessment followed (USEPA, 2011) guidelines to determine the Average Daily Dose (ADD) and Incremental Lifetime Cancer Risk (ILCR) for both children and adults through the inhalation pathway. Findings showed that children experienced higher exposure levels and greater carcinogenic risk than adults due to physiological factors and activity patterns, with chromium contributing the most significant cancer risk. Although the overall ILCR values were within acceptable limits (<1 × 10⁻⁴), the cumulative risks suggest potential long-term health implications, especially for vulnerable populations near mining sites. The study concludes that while non-carcinogenic risks remain low, continuous exposure could elevate cancer risk over time. It recommends the
implementation of dust control measures, periodic monitoring of soil and air quality, stricter regulation of mining operations and further research on heavy metal speciation
and multi-pathway risk assessments to safeguard public health and promote
sustainable sand mining practices.

This study evaluated the non-carcinogenic health risks associated with dermal exposure to heavy metals chromium (Cr), lead (Pb) and zinc (Zn) in groundwater from Ikpeshi, Edo State, Nigeria. The research aimed to quantify metal concentrations, assess health risks across population groups, identify contamination sources and propose mitigation strategies. Groundwater samples were analyzed and risk assessment models were applied using Chronic Daily Intake (CDI), Hazard Quotient (HQ) and Hazard Index (HI) frameworks as outlined by the United States Environmental Protection Agency (USEPA, 2004). Results revealed that chromium exhibited the highest mean concentration (0.177 mg/L), followed by zinc (0.257 mg/L) and lead (0.016 mg/L). Both Cr and Pb levels exceeded the permissible limits set by the World Health Organization (WHO, 2017) and USEPA, primarily due to artisanal and small-scale mining, mine tailings leaching and oxidation of metal-bearing minerals within the Igarra schist belt. Risk assessment outcomes indicated that children are more vulnerable to dermal exposure than adults, given their higher skin surface area-to-body weight ratio and frequent water contact. Chromium was identified as the dominant contributor to non-carcinogenic risks, followed by lead, while zinc showed minimal contribution. Some HI values for children exceeded unity, indicating potential chronic health effects and the mean carcinogenic risk (CR) for Cr approached the USEPA threshold of 1 × 10⁻⁴. The study concludes that chromium and lead pose significant public health concerns in Ikpeshi groundwater. The findings emphasize the need for effective groundwater monitoring, regulation of mining effluents and community-based mitigation strategies such as the use of affordable household filtration systems, rainwater harvesting and public health education to reduce dermal exposure risks and safeguard water quality.

The indiscriminate disposal of solid waste and the proliferation of open dumpsites pose serious threats to soil quality, groundwater integrity and plant health. This study evaluated the ecological risk associated with heavy metals in soils collected around open dumpsites in Oluku, Benin City, Edo State, Nigeria. Ten soil samples were randomly collected using an auger and analyzed for heavy metal concentrations using Atomic Absorption Spectrophotometry (AAS). The mean concentrations of the analyzed metals ranged from 1.22 mg/kg for Cu to 3.05 mg/kg for Mn, following the decreasing order: Mn > Cd > Pb > Cr > Ni > Co > Zn > Fe > Cu. The contamination factor (CF) values for Fe, Zn, Cu, Pb, Cd, Mn, Ni, Cr and Co were 1.23, 1.26, 1.22, 1.95, 2.48, 3.05, 1.36, 1.42 and 1.29, respectively, indicating moderate contamination by Cd and considerable contamination by Mn. The ecological risk factor (Eir) of individual metals revealed that Cd (mean = 74.4) contributed the highest ecological risk, followed by Mn (30.58) and Pb (9.77). The overall potential ecological risk index (RI) was 133.92, suggesting a moderate level of ecological risk in the study area. The findings imply that uncontrolled dumping and anthropogenic activities contribute significantly to the accumulation of toxic metals in the soil, which may pose long-term environmental and health risks. Proper waste management strategies and periodic monitoring of soil quality are therefore recommended to mitigate further contamination and safeguard environmental health.

Heavy metal contamination in soils has become a critical environmental and public health
concern, particularly in regions affected by anthropogenic activities such as mining, industrialization, and poor waste management. This study evaluates the potential non- carcinogenic health risks associated with the inhalation of heavy metals in contaminated soils within Imeke , Etsako-West Local Government Area, Edo State, Nigeria. Soil samples were
systematically collected from varying depths across the study area and analyzed for selected
heavy metals, including lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni), arsenic (As), copper (Cu), zinc (Zn), and iron (Fe), using Atomic Absorption Spectrophotometry (AAS). Standard geochemical indices such as the Enrichment Factor (EF), Geo-accumulation Index
(Igeo), and Pollution Load Index (PLI) were employed to assess the extent of metal contamination. Health risk assessment was conducted following the United States Environmental Protection Agency (USEPA,1989;2004) guidelines, focusing on non-carcinogenic exposure pathways through inhalation. Parameters such as the Average Daily Dose (ADD), Hazard
Quotient (HQ), and Hazard Index (HI) were computed for both adults and children populations to quantify potential health impacts. The results revealed varying degrees of heavy metal
enrichment, with some metals exceeding permissible limits, indicating moderate to considerable
contamination. The calculated hazard indices for certain metals exceeded the acceptable
threshold (HI > 1), suggesting potential adverse health effects, particularly among vulnerable
populations. The study underscores the significance of continuous monitoring, effective land-use planning, and implementation of remediation measures to mitigate the health implications of soil-borne heavy metals in the study area