HEAVY METALS

In this study, the levels of tin (Sn), antimony (Sb), iron (Fe), cadmium (Cd), lead (Pb), and zinc (Zn) in soil and vegetables were examined, as well as the potential health risks of eating vegetables obtained from areas around second cemetery, Iyakpen, Benin City, Edo state, Nigeria. Soil samples were collected with hand auger from 0 – 20cm depth, air-dried, powdered, and sieved. Four different vegetables (mango, orange, potato and bitter-leaf) were also were randomly collected from around the cemetery and transported to University of Benin Civil engineering laboratory, Benin City, Nigeria, for sample preparation. The vegetables were washed with distilled water to remove any traces of dirt, separated, air-dried and further dried in oven for 72 h at 65 °C to attain constant weight. The dried leaves were then pounded with a mortar and pestle and converted to powder and stored each in a plastic bag for analysis. The soil and vegetable samples were analyzed with a wavelength dispersive X-ray fluorescence spectrometer (SKYRAY INSTRUMENT EDX3600B). Health risk indication parameters (health risk index, daily intake of heavy metals and target health quotient) were evaluated.

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.

Aquatic ecosystems are often subject to contamination by heavy metals due to human and natural activities. This study was conducted to determine the concentrations of heavy metals present in water, sediment and fish samples collected from Ikpoba River, Benin City, Nigeria. Samples were collected over from June to August 2023 and analysed using standard methods. The findings showed that while Cd and Pb were not detected in the water, Ni and Cr exceeded permissible limits. However, the concentrations of Co were within limits. Sediment samples had comparatively low heavy metal content. Benthic fish were found to have higher concentrations of heavy metals than pelagic fish. However, the concentrations of these metals in the samples were below the recommended limits for heavy metals in food. Therefore, it was concluded that the fish in the study area are safe for consumption but the water is not. Hence, routine surveillance and implementation of measures to protect water quality such as prevention of waste discharge are recommended

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.

Heavy metal contamination in aquatic ecosystems is a growing concern due to its persistence, bioaccumulation potential, and toxicity to both wildlife and humans. Amphibians, due to their permeable skin and dual aquatic-terrestrial life cycle, serve as critical bioindicators of environmental pollution. However, traditional bioaccumulation studies often involve lethal sampling, which can negatively impact amphibian populations already facing global decline. This study employed a non-lethal sampling technique using toe clips from amphibians to assess heavy metal contamination in water, sediment, and amphibian tissues from Ikpe River, Edo State, Nigeria, the amphibian toe clips were collected between the months of January to September 2022.
The concentrations of iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), lead (Pb), cadmium (Cd), and nickel (Ni) in surface water, sediment, and amphibian toe clips with the aim of evaluating the effectiveness of amphibian toe clips in the assessment of heavy metals accumulating in amphibians from three stations along Ikpe River, influenced by anthropogenic activities. Analysis of heavy metals in the samples were carried out using Atomic absorption spectroscopy (AAS)

Industrial activities contribute deeply to high emission rates of particulate matter (PM) and other pollutants into the ambient air. The siting of industrial plants in proximity to a populated area can have adverse effects on human health and the environment at large. The industrialization and urbanization of Sagamu city in Ogun state, has led to increased pressure on the city especially on air quality. The chemical complexity of airborne particles makes it necessary to consider their composition and sources of emission. This study was aimed at quantifying Fine particulate (PM2.5) and its heavy metals content in ambient air of industrial areas in Sagamu, Ogun state. The study locations of this research work were Ikorodu- Sagamu industrial area (majorly metal recycling industries) and Sagamu- Abeokuta interchange industrial area (majorly a mixed of Food, Agro￾allied and Brewery industries). The control site is located at Ode-lemo farm settlement in Sagamu, Ogun state. A total of 108 air samples of fine air particulate (PM2.5) were collected. Triplicate samples were collected each month with the aid of Conical Inhalable Sampling (CIS) head at a flowrate of 3.5Lmin-1 for 8hrs per day and for a period of one year. Meteorological data were collected simultaneously with PM2.5 via a specialised weather monitoring equipment (Automated Meteorological station). The PM2.5 filter papers collected were carefully sealed in a polythene bag and preserved prior to the laboratory for analysis. The PM2.5 mass concentration was computed gravimetrically. The loaded filters were subjected to acid digestion prior to analysis. Sixteen (16) metals were identified and quantified using Inductively Coupled Plasma- Optical Emission Spectrometer ICP-OES). Pollution indices such as Contamination factor (CF), Degree of contamination (DC) and Pollution index load (PLI) were assessed on the two industrial areas. Source identification and profiling of PM2.5- bound metals were determined using multivariate analysis which included Enrichment factor, inter-metallic correlation matrix, Principal component analysis (PCA) and Cluster analysis (CA). The two predictive models, Linear Regression Model (LRM) and Gamma Regression Model(GLM) were acquired and tested using the data produced from this work and a software tool R version 2024 which is user friendly.