Contamination and Health Risk Assessment of Heavy Metals in the Soil of Major Cities in Mongolia

Batsuren Dorjsuren,Byambatseren Chuluunpurev,Chultem Batbold,Batdelger Byambaa,Sonomdagva Chonokhuu,Enkhchimeg Battsengel

doi:10.3390/ijerph16142552

Abstract

Using the case of Ulaanbaatar, Erdenet, and Darkhan cities from Mongolia, the study aimed to assess the contamination level and health risk assessment of heavy metals (As, Cr, Pb, Ni, and Zn) in urban soil. A total of 78 samples was collected from a variety of functional areas. The geoaccumulation index (Igeo) and integrated pollution index (IPI) were used in pollution assessment, while the health risk was scored using a hazard quotient (HQ) and health index (HI) for non-carcinogenic heavy metals, as well as a lifetime average daily dose (LADD) for carcinogenic heavy metals. The results show that the concentration of heavy metals in the soil samples taken from Darkhan city, which presented “uncontaminated” values in terms of Igeo for all metals, was relatively lower than other cities within the contamination assessment. Furthermore, the Igeo value signified “uncontimated to heavily contaminated” soil in the Ulaanbaatar and Erdenet cities. Typically, as for the IPI that observed similar trends with Igeo, the mean IPI values in Ulaanbaatar, Erdenet, and Darkhan were 1.33 (moderate level of pollution), 1.83 (moderate level of pollution), and 0.94 (low level of pollution), respectively. In terms of the assessment of potential health risk, there was a particular or different level of ingestion, dermal contact, and inhalation exposure pathway for human health. Among these three different pathways, the ingestion was estimated by the main contributor for health risk. Each value of HQ and HI indicated that soil heavy metals of studied cities were at a safe level (<1) or had the absence of a significant health risk there. In addition, the potential health risk for children was greater than for adults, where heavy metal values of HI for children had a high value compared to adults. We estimated carcinogenic risks through the inhalation exposure, and as a result, there were no significant risks for human health in the studied cities from three elements (As, Cr, and Ni).

Highlights

During the last few decades, the properties of heavy metals in urban soils and street dust from urban roads have gained increasing interest, as indicated by the increasing number of papers [1]
With contamination level in its present condition, by using the geoaccumulation index and integrated pollution index, we indicate the soil heavy metal pollution in three cities in Mongolia
In order to define the health risk assessment, the exposure doses were calculated using the concentration of heavy metals, and the non-cancer risk assessment result was revealed for each analyzed element and city

Summary

Introduction

During the last few decades, the properties of heavy metals in urban soils and street dust from urban roads have gained increasing interest, as indicated by the increasing number of papers [1]. This increase is probably attributed to the potential public health risk due to the intake of heavy metals. The mean concentrations of As (12.78), Cr (65.70), Pb (18.06), Ni (29.30), and Zn (155.17) mg/kg in urban soil of all the sites from Erdenet were from 1.2 to 3.2 times higher than their background values. Whereas the mean concentrations of Cr, Pb, Ni, and Zn were much lower than their MPC, As was 2.13 times higher than the MPC (Table 4)

Objectives

Methods

Results

Discussion

Conclusion