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article · Asian Journal of Physical and Chemical Sciences

Environmental and Human Health Risk Assessment of Heavy Metals in Soils from Automobile Mechanic Villages in Enugu State, Nigeria

In plain language

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. Researchers analysed soil samples for ten heavy metals using Atomic Absorption Spectrophotometry and evaluated contamination and risks using various indices. Zinc showed the highest concentrations, but mercury was identified as the principal contaminant, exhibiting high contamination factors and moderate-to-strong pollution. Coal Camp generally recorded higher contamination indices than Emene. Non-carcinogenic health risks from soil ingestion were low, but incremental lifetime cancer risks were observed, with children showing higher estimated risks. Overall, while metal pollution was low based on the Pollution Load Index, mercury posed a significant ecological risk.

Key takeaways

  • Heavy metal contamination, ecological risk, and human health risks were assessed in soils from automobile mechanic villages in Enugu State, Nigeria.
  • Mercury was identified as the principal contaminant of concern, contributing significantly to ecological risk in both locations.
  • While overall metal pollution was low based on the Pollution Load Index, specific metals like mercury showed moderate-to-strong pollution levels.
  • Non-carcinogenic health risks from soil ingestion were low, but incremental lifetime cancer risks were observed, with children showing higher estimated risks than adults.
  • Improved management of automobile wastes and regular monitoring of soils in mechanic villages are recommended.

Why it matters

This research highlights how activities in automobile mechanic villages can contaminate local soils with heavy metals, posing risks to ecosystems and human health. Understanding these risks is crucial for developing strategies to protect communities, especially children, from exposure to harmful pollutants and for ensuring environmental sustainability in affected areas.

Commercialisation angle

The abstract recommends improved management of automobile wastes and regular monitoring of mechanic-village soils. This suggests a need for environmental monitoring services, waste management solutions, and regulatory compliance tools for local authorities and businesses operating in or near such areas. This research provides foundational data for policy development and applied environmental management.

AI-generated from the published abstract. Always read the original work before citing.

Abstract

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.

Research topics

  • Heavy metals in environment
  • Heavy Metal Exposure and Toxicity
  • Geochemistry and Elemental Analysis

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DOI: 10.9734/ajopacs/2026/v14i3339

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