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

Assessment of heavy metals and radionuclides pollution in an agro-mining river system: implications for environmental and human health

This study assessed heavy metal (Cu, Ni, Pb, Zn and Cd) and radionuclide (²²⁶Ra, ²³²Th and ⁴⁰K) pollution and associated risks in the Likuyu River system, Tanzania. Surface water and sediments were collected from five sites along a 22.7 km river stretch, while soils and leafy vegetables were sampled from adjacent farms. Heavy metals were analysed by atomic absorption spectrometry and radionuclides by high-purity germanium gamma spectrometry. Risk assessment used contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI), bioaccumulation factor (BAF), non-carcinogenic risk, carcinogenic risk (CR), annual effective dose (AED), radium equivalent activity (Raeq), annual ingestion dose (Ding) and excess lifetime cancer risk (ELCR). Heavy metals in river water were below detection limits and complied with WHO drinking-water limits: The Zn, 3–5 mg L⁻¹; Cd, 0.003 mg L⁻¹; Ni, 0.07 mg L⁻¹; Cu, 2.0 mg L⁻¹; and Pb, 0.0135 mg L⁻¹. The Ni in sediments at Sites A and E reached 32.1 ± 26.90 and 35.97 ± 6.51 mg kg⁻¹, respectively, exceeding the threshold effect concentration of 22.7 mg kg⁻¹ but remaining below the probable effect concentration of 48.6 mg kg⁻¹. Pollution indices indicated generally low sediment contamination, with CF values mostly below 1, Igeo values from −5.49 to −0.40, and PLI values from 0.077 to 0.251, although slight Zn enrichment occurred at Site A (CF = 1.14). Soils were weakly polluted, with PLI values of 0.078–0.105; however, Site SOD showed localized Ni enrichment, with CF = 1.577 and Igeo = +0.07, reaching 107.2 ± 1.40 mg kg⁻¹, exceeding the TBS limit of 50 mg kg⁻¹. Bioaccumulation results showed strong Zn uptake in napa cabbage (BAF >12), cowpea (BAF ~8) and okra (BAF ~6), and Pb accumulation in okra (BAF ~6) and cowpea (BAF ~5), whereas Ni and Cd had BAF

Heavy Metal Contamination and Ecological Risk Assessment of Soils Around Mzedi Municipal Dumpsite, Blantyre, Malawi: Implications for Food Safety in Subsistence Farming Areas

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.

Heavy Metal Contamination, Source Identification, Human Health Risk and Sustainability Assessment of Soils Across Industrial, Agricultural, and Residential Land-Use Areas in Rivers State, Nigeria

Heavy metal contamination poses significant ecological and public health concerns due to its persistence, toxicity, and bioaccumulative potential of toxic metals, threatening environmental quality and sustainable development. This study evaluated the distribution, pollution status, health risks, and sources of heavy metals in soils from industrial, agricultural, and residential areas of Rivers State, Nigeria, using Inductively Coupled Plasma–Mass Spectrometry (ICP-MS). Elevated concentrations of As, Mn, Se, Zn, and Co were detected across the study locations. Arsenic recorded the highest concentration in the Trans-Amadi industrial area (366.8 mg/kg), while Mn and Zn reached maximum concentrations of 1312 mg/kg and 327.9 mg/kg in Woji and Egi, respectively, exceeding the DPR limits for soil HMs. Pollution indices, including contamination factor, geo-accumulation index, enrichment factor, pollution load index, and Nemerow Integrated Pollution Index, revealed moderate to severe contamination, with the industrial zone exhibiting a NIPI value of 12.5. Health risk assessment identified ingestion as the dominant exposure pathway. Hazard quotient values for As (9.15) in the children category exceeded USEPA-acceptable limits, indicating potential non-carcinogenic risks. Carcinogenic risk assessment identified arsenic as the principal carcinogenic contaminant, with ingestion-derived Incremental Lifetime Cancer Risk (ILCR) values in the industrial area exceeding the USEPA maximum acceptable lifetime cancer risk threshold (1 × 10−4), particularly among children, whereas the carcinogenic risks associated with the other investigated metals generally remained within acceptable or tolerable limits. Source identification indicated that industrial emissions, vehicular activities, waste disposal, and agricultural practices were the primary contributors to heavy metal accumulation. These findings provide critical scientific evidence for targeted remediation, pollution prevention, and informed health-risk environmental management to protect soil quality, ecosystem integrity, and public health. The study supports evidence-based policies that advance sustainable land management, environmental protection, and progress in Rivers State, Nigeria.

Assessment of Human Health Risks Posed by Soil Contamination with Heavy Metals and Arsenic in a City with the Developed Metalworking Industry

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.

Groundwater Contamination and Probabilistic Health Risk Assessment of Heavy Metals in Coal Mining Areas of Punjab, Pakistan

Concentrations, Human Health Risks, Household Knowledge and Awareness of Heavy Metal Contamination in Ogbanokwute Spring Water, Enugu State, Nigeria

Heavy metal contamination of drinking water poses significant environmental and public health concerns due to the persistence, toxicity, and bioaccumulation of these pollutants. Consequently, the objective of this paper was to evaluate the Concentrations, Human Health Risks, Household Knowledge and Awareness of Heavy Metal Contamination in Ogbanokwute Spring Water, Enugu State, Nigeria using appropriate standard methods including structured questionnaire administered to 360 households. Chromium, lead, arsenic, and silver were not detected, while cadmium, aluminium, and zinc concentrations were within the World Health Organization (WHO) permissible limits. Heavy Metal Pollution Index (HPI) values (19.80 and 58.92), Metal Index (MI) values (0.658 and 1.537), and Degree of Contamination (Cd) values (−6.342 and −5.463) indicated low levels of contamination. Hazard Quotient (HQ) and Total Hazard Index (THI) values were below 1, indicating negligible non-carcinogenic health risks. Respondents demonstrated low-to-moderate knowledge and low awareness of the health effects of heavy metal contamination despite their heavy reliance on untreated spring water. Although the spring water is currently safe for consumption, inadequate public awareness may increase future vulnerability should contamination occur. Overall, Ogbanokwute Spring Water is presently safe for drinking with respect to heavy metal contamination. However, continuous water quality monitoring and community-based environmental health education are recommended. By integrating water quality assessment, human health risk evaluation, and community perception, this study provides evidence to support informed drinking water management and public health interventions.