Health Risk Assessment of Heavy Metals Accumulated on PM2.5 Fractioned Road Dust from Two Cities of Pakistan.

Haseeb Tufail Moryani,Jiangkun Du,Shuqiong Kong,Jianguo Bao

doi:10.3390/ijerph17197124

Abstract

The aim of this study is to identify and investigate levels of toxic heavy metals in PM2.5 fractioned road dust to better understand the associated inhalation risk and potential health impacts. To achieve this aim, concentrations of seven traffic generated heavy metals (Cu, Pb, Zn, Cd, Ni, Sb, and Cr) were determined in the PM2.5 fraction of road dust samples from four different locations (offices, residential, hospital, and school) in two cities (Karachi and Shikarpur) of Pakistan using ICP-MS. The average concentration values of heavy metals in Karachi were as follows: 332.9 mg/kg Cu, 426.6 mg/kg Pb, 4254.4 mg/kg Zn, 62.3 mg/kg Cd, 389.7 mg/kg Ni, 70.4 mg/kg Sb, 148.1 mg/kg Cr, whereas the average concentration values of heavy metals in Shikarpur were 245.8 mg/kg Cu, 538.4 mg/kg Pb, 8351.0 mg/kg Zn, 57.6 mg/kg Cd, 131.7 mg/kg Ni, 314.5 mg/kg Sb, 346.6 mg/kg Cr. The pollution level was assessed through two pollution indices enrichment factor (EF) and geoaccumulation index (Igeo). These indices showed moderate to extreme level pollution in studied areas of both cities. The health risk assessment through inhalation contact was conducted according to the United States Environmental Protection Agency’s (USEPA) model for children and adults. Both non-cancerous and cancerous risks were characterised in the road dust samples for each location. As yet, there is not a single study on the concentrations of heavy metals in PM2.5 fractions of road dust in Karachi and Shikarpur, findings of this research will facilitate researchers for further investigations in current field.

Highlights

Road dust is known as a heterogeneous mixture of environmental pollutants originated from natural as well as anthropogenic sources
Concentrations of Cu, Pb, Zn, Cd, Ni, Sb, Cr were measured in PM2.5 fraction of road dust samples from four areas of Karachi and Shikarpur, Pakistan
The minimum, maximum, mean and standard deviation (SD) of total metal concentrations associated with PM2.5 fraction are summarized in Tables 2 and 3 and compared to other major Asian cities in on the basis of land use types the descending order with respect to average concentration values of toxic metals in Karachi and Shikarpur ranked as residential area > hospital area > offices area

Summary

Introduction

Road dust is known as a heterogeneous mixture of environmental pollutants originated from natural as well as anthropogenic sources. Erosion, weathering, resuspension, and deposition of soil particles are considered the major road dust sources, whereas emissions from several activities of urbanisation such as traffic, industrial and household emissions are considered the main anthropogenic sources [1]. In addition to a variety of other contaminants, road dust is a source of metal pollutants in urban areas, which can damage human health through ingestion, inhalation or dermal contact [4]. Resuspension of road dust is an important source of atmospheric particulate matter, in the 2.5μm fraction (PM2.5 ) [5,6,7].

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