Evaluation of health risks associated with potential toxic elements (PTEs) in urban public automobile parks soil dust in Northwest, Nigeria

Public automobile parks soil dust is a significant source of inhalable particulate matter in metropolitan environments worldwide. This study aims to examine the health risks associated with ten potential toxic elements (As, Ba, Cd, Cr, Cu, Ni, Hg, Li, Zn and Pb) and their composition in motor parks in the Northwest region of Nigeria. For this, dust samples are collected from 13 motor parks in the study region. The collected samples are digested and analysed for ten potential toxic element using Inductively Coupled Plasma Mass Spectrometer while Hg was analysed using a Cold Vapor Atomic Fluorescence Spectrophotometer. The highest mean concentration is noted for Ba (189.37 mg/kg) followed by Zn (157.53 mg/kg), Cu (115.26 mg/kg) and Cr (67.01 mg/kg). Enrichment factor (EF) and contamination factor (CF) are calculated as Ba and Zn show the highest EF and CF. Additionally, the health risk assessment for PTEs shows that the elements with the highest health index are As, Pb, Cr, and Ba; the health index of these elements indicates a potential health risk; ingestion is the main pathway, and children appear to be at a higher risk than adults. According to guidelines 10-4 –10-6, the risk of cancer from potentially toxic elements in motor park dust was found to be low for both adults and children in three pathways. Different pollution levels are reflected in the geo-accumulation index, with certain metals presenting serious ecological risks. The study also reveals different pollution patterns in automobile parks by comparing its findings with those of other studies conducted around the world. Principal component analysis (PCA) provided justification for the metal content in dust that was regulated by a combination of anthropogenic and natural sources. The report highlights the necessity of putting remedial measures into place to address the environmental and public health problems associated with metal pollution.

公共停车场土壤粉尘是全球城市环境中可吸入颗粒物的重要来源。本研究旨在探究尼日利亚西北部区域机动车停车场土壤粉尘中十种潜在毒性元素（Potential Toxic Elements，以下简称PTEs，包含As、Ba、Cd、Cr、Cu、Ni、Hg、Li、Zn、Pb）的组成特征及其关联的健康风险。为此，本研究于研究区域内的13处机动车停车场采集了粉尘样品。采集的样品经消解处理后，采用电感耦合等离子体质谱仪（Inductively Coupled Plasma Mass Spectrometer，ICP-MS）分析十种PTEs的含量，其中汞（Hg）则采用冷蒸气原子荧光分光光度计（Cold Vapor Atomic Fluorescence Spectrophotometer，CVAFS）进行检测。各元素的平均浓度以钡（Ba）最高，达189.37 mg/kg，其后依次为锌（Zn，157.53 mg/kg）、铜（Cu，115.26 mg/kg）与铬（Cr，67.01 mg/kg）。研究计算了富集因子（Enrichment Factor，EF）与污染因子（Contamination Factor，CF），结果显示钡（Ba）与锌（Zn）的EF与CF值均为最高。此外，针对PTEs的健康风险评估结果显示，健康指数最高的元素为砷（As）、铅（Pb）、铬（Cr）与钡（Ba）；上述元素的健康指数表明存在潜在健康风险，且经口摄入为主要暴露途径，儿童所面临的健康风险显著高于成人。依据10^-4~10^-6的癌症风险阈值指南，机动车停车场土壤粉尘中PTEs经三种暴露途径所引发的癌症风险，在成人与儿童群体中均处于较低水平。地质累积指数（Geo-accumulation Index）的计算结果反映了不同的污染程度，部分金属元素呈现出严重的生态风险。本研究通过与全球其他同类研究的结果进行对比，揭示了不同区域机动车停车场的污染特征差异。主成分分析（Principal Component Analysis，PCA）结果表明，粉尘中金属元素的含量主要受人为源与自然源的共同调控。本研究强调，需采取针对性修复措施，以应对金属污染引发的环境与公共健康问题。