2026· Dutse Journal of Pure and Applied Sciences· 0 citations
Abstract
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.
Urban soil contamination by potentially toxic elements (PTEs) poses increasing ecological and public health concerns in rapidly industrializing environments. This study assessed PTE concentrations, contamination status, ecological risks, and human health implications of soils from Abuja and Kano, Nigeria, using deterministic and probabilistic risk assessment approaches. Sixteen topsoil samples (0–15 cm) collected from residential, commercial, and industrial locations were analyzed for Pb, Cd, Ni, Cr, and Al using atomic absorption spectrophotometry following aqua regia digestion. Mean concentrations of Pb (9.60 ± 4.29 vs 6.38 ± 3.08 mg/kg), Cd (1.53 ± 0.53 vs 1.12 ± 0.45 mg/kg), Ni (7.66 ± 1.71 vs 5.85 ± 1.42 mg/kg), Cr (9.86 ± 1.35 vs 8.23 ± 1.61 mg/kg), and Al (364.75 ± 96.47 vs 291.88 ± 80.39 mg/kg) were significantly higher in Kano than Abuja. Contamination assessment showed moderate Cd contamination (CF = 3.73–5.10), PLI values of 1.42 (Kano) and 1.16 (Abuja), Igeo values indicating unpolluted-to-moderately polluted soils, and enrichment factors suggesting moderate anthropogenic enrichment of Cd and Pb. Ecological risk indices revealed Cd as the dominant contributor, with Eᵣ values of 111.9–153.0 and total RI values of 176.4–229.8, indicating moderate-to-considerable ecological risk. Estimated daily intake followed the order ingestion > dermal > inhalation, with children exhibiting higher exposure levels than adults. Non-carcinogenic risks remained acceptable (HQ and HI < 1), with maximum HI values of 0.38 for children and 0.21 for adults in Kano. Incremental lifetime cancer risks values were highest for Cd (6.39 × 10⁻⁶ in Kano children and 4.38 × 10⁻⁶ in Kano adults) and lowest for Ni (4.41 × 10⁻⁹ in Kano children and 3.02 × 10⁻⁹ in Kano adults), with lower corresponding values in Abuja (9.78 × 10⁻⁷–1.71 × 10⁻1⁰ for children and 6.72 × 10⁻⁷–1.17 × 10⁻1⁰ for adults), all remaining within acceptable risk thresholds. Monte Carlo simulation confirmed consistently higher exposure probabilities in Kano. Continuous monitoring, stricter emission control, and targeted child-focused exposure mitigation are recommended for sustainable urban environmental management.
Aliyu Zakari-Jiya, I. O. Akande, G. Udom et al.· Discover Environment· 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
This study evaluated the influence of multiple traffic-related conditions, including proximity to a road, car parking, highway, road junction, and transport stop, commonly observed yet largely overlooked in many non-metropolitan cities of developing nations, on trace element (TE) contamination in roadside soil and the associated risks in a secondary South African city. Among the evaluated TEs (As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Zn), mean Cu and Pb concentrations exceeded national soil quality guidelines at 100% and 86% of sites, respectively, whereas pollution assessment revealed generally moderate Sb, Pb, Cr, Ni, Co, Mn, and Zn contamination at > 71% of sites; indicating 73% of TEs as potential environmental threats. Of the seven examined localities, a mean pollution load index above 1 suggested soil pollution at a site affected by most traffic conditions. Regression analysis indicated positive relationships between road proximity and concentrations of all TEs, with significant (p < 0.05) associations for 75% of the identified contaminants, along with As and Ba. Significant positive correlations between TEs exhibiting higher contamination suggested shared sources. This was further supported by principal component analysis, which associated 73% of TEs with one or more traffic variables, primarily road proximity, transport stop, and highway, and secondarily car parking. Moreover, origin from multiple traffic sources was suggested for most TEs. Nearly moderate ecological risks for Cd and Pb at two sampling points, and potential cancer risks for children from As, require follow-up investigation. The findings provide valuable insights into the globally underexamined pollution footprint of multiple traffic-related factors and highlight the need for their management to promote ecosystem sustainability in comparable cities.
This study assessed heavy metal contamination and associated ecological and human health risks at a municipal dumpsite using established pollution indices and risk models. Soil samples collected from three stations (A–C) during rainy and dry seasons were analyzed for Cd, As, Fe, Zn, Cr, Pb, and Hg. Results showed clear seasonal and spatial variations, with higher concentrations generally recorded in the dry season. Cadmium exhibited the highest contamination, with CF values ranging from 12.74–23.40 and EF values of 191.6–211.6, indicating very high anthropogenic enrichment. The Igeo values for Cd (3.09–3.96) classified the site as strongly polluted, while Pb showed moderate pollution (Igeo: 0.60–1.65). Other metals remained largely within unpolluted categories (Igeo ≤ 0). The degree of contamination (Cd) ranged from 16.74–31.78, indicating considerable contamination, while PLI values (0.51–1.01) suggested moderate overall pollution with localized deterioration. Ecological risk assessment identified Cd as the major contributor to risk, reflecting its high toxicity and elevated concentration. Human health risk assessment revealed ingestion as the dominant exposure pathway. The total hazard index (THI) for children (3.97 × 10²) was significantly higher than for adults (4.25 × 10¹), exceeding the safety threshold (THI > 1). Arsenic and cadmium contributed most to risk, with ingestion HQ values of 205.3 and 70.0, respectively, for children. Dermal exposure contributed moderately, while inhalation was negligible (10⁻³).Overall, the dumpsite poses significant ecological and human health risks, necessitating improved waste management, environmental monitoring, and remediation strategies.
Ezechi, Ejikeme Chigozie, Iyioku Magnus Ugochukwu· 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
Introduction: The study was conducted to assess health risks posed by soil pollution to the population of Kolchugino, one of the old industrial centers of the Vladimir Region.
Objective: To assess carcinogenic and non-carcinogenic health risks to the population of the city of Kolchugino caused by soil pollution with heavy metals and arsenic from metal works.
Materials and Methods: Health risk assessment was conducted in accordance with Russian Guidelines R 2.1.10.3968–23 based on soil concentrations of gross forms of As, Co, Cr, Cu, Ni, Pb, and Zn measured in the city of Kolchugino in 2023. Both carcinogenic and non-carcinogenic risks from oral, inhalation, and dermal exposures were calculated by three age groups (children under 7 years of age, children aged 7–17 years, and adults aged 18 years and over). Statistical processing and mathematical calculations were performed using Microsoft Excel.
Results: We established that values of the total carcinogenic risk were acceptable and ranged from 4.92×10–5 to 6.99×10–5. Ingestion was the priority route of exposure contributing the most to the carcinogenic risk and the total hazard index. The highest hazard indices were estimated for children under 7 years of age. Contamination of urban soils with heavy metals and arsenic posed the highest risks of disorders of the skin and of the nervous, cardiovascular, respiratory, and endocrine systems in the population of Kolchugino. The limitations of the study were related to exposure estimates, reference doses, and slope factors.
Conclusion: Our findings show that carcinogenic and non-carcinogenic health risks posed by soil contamination in the industrial city of Kolchugino are within acceptable limits. The central nervous system, especially in children, is the most vulnerable to non-carcinogenic effects of heavy metals.
A. Martsev, O. Selivanov, Yuri N. Kurbatov et al.· ЗДОРОВЬЕ НАСЕЛЕНИЯ И СРЕДА О...· 0 citations