Jul 2026· IPS Journal of Public Health· Vol 6, pp. 798-806· 0 citations· 45 references
Abstract
Soils were sampled from the decommissioned auto-mechanic village in Old Nekede, Owerri, Imo State, Nigeria, and analysed for six trace metals (Co, Ni, Fe, Zn, Pb and Al) in both the topsoil (0–15 cm horizon) and subsoil (15–30 cm horizon). Sampling stations were established at minimum inter-station distances of 100 m on a georeferenced grid. Ecological risk was assessed using the Hakanson potential ecological risk index (RI) and the monomial potential ecological risk factor (Er). Human health risk via ingestion, dermal contact, and inhalation pathways was calculated for adult and child receptors at each station following established USEPA protocols. Residual concentrations of Fe and Zn dominated the contamination profile, with topsoil Fe reaching 1,267.25 mg/kg and topsoil Zn reaching 253.00 mg/kg. Pb and Ni were below the analytical detection threshold (<0.001 mg/kg) at all stations. Ecological risk index values (RI) ranged from 13.9 to 59.0, classifying the site as low-to-moderate ecological risk, with the highest individual Er associated with cobalt. Non-carcinogenic hazard indices (HI) exceeded the USEPA threshold of 1.0 for child receptors at three of the five stations investigated, driven primarily by the ingestion pathway and attributable to Zn and Co. Cobalt carcinogenic risk remained within the USEPA acceptable range (10−6 to 10−4) for both receptor groups at all stations. Passive site recovery over five years post-relocation has proven insufficient. Findings support the need for ecological restoration, groundwater management, and enforceable land-use policy.
Automobile mechanic activities can introduce potentially toxic metals into surrounding soils through the disposal of spent engine oil, metallic scraps, batteries and other vehicle-related wastes. This study assessed heavy metal contamination, ecological risk and potential human-health risks in soils from automobile mechanic villages at Coal Camp and Emene, Enugu State, Nigeria. Soil samples were digested using a nitric acid–perchloric acid mixture and analysed for Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn using Atomic Absorption Spectrophotometry (AAS). Contamination and ecological risks were evaluated using the contamination factor (CF), pollution load index (PLI), degree of contamination (Cdeg), modified degree of contamination (mCd), geo-accumulation index (Igeo) and potential ecological risk index (PERI). Human-health exposure was evaluated through dermal contact and soil ingestion using estimated average daily dose (ADD), hazard quotient (HQ), hazard index (HI) and incremental lifetime cancer risk (ILCR). Zinc recorded the highest concentrations at Coal Camp (1.2338 mg/kg) and Emene (1.2327 mg/kg), whereas mercury exhibited the highest contamination and ecological-risk contribution. The highest CF values were recorded for Hg at Coal Camp (10.075) and Emene (7.280), while Igeo values of 2.748 and 2.279 indicated moderate-to-strong Hg pollution, respectively. Coal Camp recorded higher Cdeg (11.270), mCd (1.127), PLI (0.0133) and RI (436.52) than Emene, which recorded Cdeg (8.417), mCd (0.842), PLI (0.0124) and RI (322.98). All HQ and HI values were below 1, indicating low non-carcinogenic risk through soil ingestion. Total ILCR values ranged from 4.882 × 10⁻⁷ to 1.359 × 10⁻⁶, with children showing higher estimated risks than adults. Overall, the soils exhibited low overall metal pollution based on PLI, but Hg represented the principal contaminant of concern and contributed substantially to ecological risk. Improved management of automobile wastes and regular monitoring of mechanic-village soils are recommended.
Unknown authors· Asian Journal of Physical an...· 0 citations
Heavy metal contamination of agricultural soils near the Ota Industrial Estate, southwestern Nigeria, was assessed using a six-module Python pipeline that integrates geochemical indexing, ecological-risk modelling, and human-health risk assessment. Cu, Pb, Zn, and Cd were analysed at 12 sites. Cu, Pb, and Zn were within WHO/FAO permissible limits. Cd concentrations exceeded the WHO/FAO guideline of 0.80 mg/kg at half of the locations (IN1--IN6, up to 3.09 mg/kg), and two locations exceeded the upper limit of 3.0 mg/kg. Contamination-factor analysis classified Pb at the vehicle-workshop zones (IN7--IN9) as considerable to very high, with CF up to 12.61, and classified Cu/Zn as moderate to very high at fabrication and galvanisation zones. The mean ecological risk index (RI) for the estate was 64.5 ± 24.1, indicating low overall risk, although Cd and Pb fell within moderate Er bands in some sub-zones. Independent recomputation showed that none of five originally proposed metal-pair correlations was significant; however, a strong Pb--Cd correlation was Bonferroni-significant (r = 0.946, p = 0.0012), indicating a shared anthropogenic source. US EPA RAGS non-carcinogenic hazard indices were below unity for adults (HI = 0.014) and children (HI = 0.126). Carcinogenic risk was not quantified because validated oral slope factors for Cd or Pb are unavailable in IRIS. The principal regulatory basis for clean-up is the Cd exceedance. The open-source pipeline provides a reproducible framework for soil-contamination assessment in West African regulatory contexts.
C. Ogunkoya, G. Layade· Terratmosphera· 0 citations
Aim: This study assessed the ecological risk posed by six heavy metals [lead (Pb), zinc (Zn), nickel (Ni), copper (Cu), chromium (Cr), and cadmium (Cd)] in soils and surface waters.
Study Design: Soil samples were collected at two depths (0–15 and 15–30 cm) from 12 stations across Onna, Mkpat Enin, Eastern Obolo, and Uyo in Akwa Ibom State. Surface-water samples were also collected, and Uyo served as the reference location.
Methodology: Composite soil samples were collected using a stainless-steel soil auger. Following acid digestion, metal concentrations were determined by atomic absorption spectrophotometry (AAS). The contamination factor (CF), degree of contamination (C-deg), geoaccumulation index (Igeo), single-metal ecological risk factor, and comprehensive potential ecological risk index (RI) were calculated using average-shale background values and the methods of Müller and Hakanson.
Results: Except for nickel at Onna Station 3 (57.5 mg/kg), which exceeded the adopted agricultural and residential soil guideline values, soil-metal concentrations were below the relevant limits. In surface water, lead and nickel exceeded the adopted WHO guideline values at all four locations, whereas chromium and cadmium exceeded the guidelines at two locations. Most CF and Igeo values indicated low contamination, although cadmium showed the greatest relative enrichment at several stations.
Conclusion: Although several stations, including the reference location, showed moderate-to-considerable single-metal risk from cadmium, RI remained below 150 at all soil stations, indicating low overall potential ecological risk. The results provide baseline information for environmental monitoring and remediation prioritisation in the studied oil-producing areas.
U. U. Ubong, A. D. Akpan, U. G. Isotuk· Asian Journal of Physical an...· 0 citations
Traffic-derived heavy metal contamination of roadside soils poses significant public health risks in rapidly urbanising sub-Saharan African cities, yet probabilistic risk assessment remains rare in this region. This study characterised lead (Pb) and arsenic (As) concentrations in surface soils (0–20 cm) at five traffic-corridor sites along an urban-to-peri-urban gradient in Benin City, Nigeria, and evaluated ecological and human health risks using geochemical pollution indices, the Håkanson ecological risk framework, and a USEPA multi-pathway human health risk assessment model augmented by Monte Carlo (MC) simulation. Soil Pb ranged from 4.38 to 16.80 mg kg⁻¹ and As from 0.81 to 2.13 mg kg⁻¹, exceeding the local geochemical control by 52–119-fold and 63–95-fold, respectively. Pollution indices referenced to global shale background classified all sites as uncontaminated (Igeo < 0; CF < 1), yet locally-normalised contamination factors indicated very high anthropogenic enrichment, exposing a critical limitation of global background standards for the inherently metal-poor soils of the Benin Formation. Ecological risk was low at all sites (RI: 3.24–5.73); however, As contributed disproportionately to composite risk due to its higher toxic response factor. Deterministic non-carcinogenic hazard indices remained below 1.0 for both children and adults. Total carcinogenic risk (TCR) from As ingestion exceeded the acceptable threshold of 1 × 10⁻⁶ at all contaminated sites (children: 1.52–2.33 × 10⁻⁵; adults: 1.31–1.99 × 10⁻⁵). Critically, MC simulation demonstrated that As carcinogenic risk exceeded 10⁻⁶ at probabilities of 61–96% for children and 43–89% for adults — identifying As ingestion as the modal, not worst-case, risk outcome. Soil As concentration (ρ = 0.71–0.83) and ingestion rate (ρ = 0.55–0.68) were the dominant sources of exposure variance. These findings provide the first probabilistic HHRA of roadside soils in Benin City and demonstrate that deterministic methods alone are insufficient to characterise As carcinogenic risk in low-concentration, high-slope-factor contexts.
Ozekeke Ogbeide, Faith Omorotionmwan· Dutse Journal of Pure and Ap...· 0 citations
Heavy metal contamination in recreational soils may present environmental and public health concerns, particularly in areas exposed to traffic, commercial activities, and other anthropogenic inputs. This study assessed the concentrations, pollution status, ecological risk, and human health risks associated with selected heavy metals in playground soil collected from Filin Police Station, Batagarawa Local Government Area, Katsina State, Nigeria. Topsoil samples were collected from three locations at a depth of 0–10 cm using a systematic sampling approach. Heavy metal concentrations were determined using atomic absorption spectrophotometry after sample preparation and acid digestion. The results were used to estimate the geo-accumulation index, enrichment factor, contamination factor, pollution load index, potential ecological risk index, target hazard quotient, hazard index, and incremental lifetime cancer risk. Iron (1.42 ± 0.0201 mg/kg), manganese (1.34 ± 0.0045 mg/kg), and chromium (1.27 ± 0.0125 mg/kg) had the highest measured concentrations, while cadmium (0.09 ± 0.0010 mg/kg) and copper (0.04 ± 0.0048 mg/kg) occurred at the lowest levels. The geo-accumulation index, contamination factor, pollution load index, and potential ecological risk index generally indicated low contamination and low ecological risk. However, enrichment factor values suggested possible anthropogenic influence for chromium, lead, and zinc. Health risk estimates indicated that dermal exposure was the main contributor to non-carcinogenic risk in both children and adults. Chromium, nickel, and cadmium indicated potential carcinogenic concern for children, while lead, chromium, and nickel indicated potential carcinogenic concern for adults.
Abdullahi Nasir, A. Usman, Aliyu Ibrahim Yaradua et al.· Asian Journal of Applied Che...· 0 citations
Uncontrolled disposal of municipal solid waste is a growing environmental concern in developing countries, contributing to heavy metal accumulation in surrounding soils and water. This study assessed the concentrations, spatial distribution, and ecological risks of heavy metals around the Mzedi municipal dumpsite in Blantyre, Malawi. Composite soil samples were collected at 0 m, 50 m, 250 m, 400 m, and 650 m from the dumpsite, while surface water samples were taken from a nearby stream receiving runoff. Samples were analyzed for cadmium (Cd), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), and cobalt (Co) using atomic absorption spectrophotometry. Contamination and risk levels were evaluated using the Contamination Factor (CF), Geo-accumulation Index (Igeo), Enrichment Factor (EF), and Potential Ecological Risk Index (PERI). Soil metal concentrations decreased with distance from the dumpsite in the order Fe > Mn > Zn > Cu > Pb > Cd > Co. Cadmium exhibited the highest contamination levels, with CF (70.00), Igeo (5.54), and EF (19.17) at 0 m indicating extremely polluted conditions and severe anthropogenic enrichment. PERI values ranged from 2,181 at 0 m to 117 at 650 m, shifting from very high to low ecological risk. Cadmium contributed > 96% of the total ecological risk, confirming it the dominant contributor to ecological risk. In surface water, Cd (0.006–0.008 mg/L) and Pb (0.025–0.030 mg/L) exceeded WHO drinking water guidelines, confirming leachate-driven contamination of the adjacent stream. While crop metal concentrations were not directly measured, the elevated soil cadmium levels indicate potential for plant uptake and possible human exposure. However, without direct crop analysis, we cannot confirm the extent of food chain transfer, quantify dietary exposure, or assess compliance with food safety standards. This highlights the critical need for targeted crop monitoring studies to validate the inferred human health risks. This study provides the first comprehensive quantitative assessment of ecological risk at the Mzedi dumpsite using multiple contamination indices and robust statistical analysis. The findings support precautionary management measures, including restrictions on farming directly on the dumpsite, upgrading of waste disposal infrastructure, and community awareness programs.
Vincent Gwengwe, E. Vunain· Resources Environment and In...· 0 citations