Health Risk Assessment, Pollution Indices and Ecological Risk of Chemical Elements in Dust and Soils of Warri Metropolis, Southern Nigeria

Abstract

BACKGROUND AND AIM: Adverse health effects have been linked with human exposure to chemical contaminants via diverse environmental pathways. This study assessed pollution levels, ecological risk and health risk of chemical elements in dust and soils of Warri Metropolis, Southern Nigeria. METHODS: Forty topsoil and settled dust samples were collected from ten sampling sites and analysed for chemical elements using Inductively Coupled Plasma Mass Spectrophotometry. The results were subjected to descriptive and inferential statistical analysis. Pollution Index (PI), Ecological Risk Index (ERI), Nemerov Integrated Pollution Index (NIPI) and Health Risk [Hazard Quotient (HQ) and Cancer Risk (CR)] were also calculated. RESULTS:Results revealed high concentrations (mg/kg) of Cu (2.1-38.4), Zn (21.4-268.0), Ag (0.015-2.720), Hg (0.09-0.51), P (120-1230) and B (3.0-7.0) in dusts; and Cu (1.0-42.7), Zn (6.2-492.0), Ag (0.016-100), Hg (0.05-0.33), P (30-1960) and B (3.0-5.0) in soils. Cu, Zn, Hg and P concentrations were highest and exceeded permissible limits in poultry farm dusts and Pessu soils. PI indicated very strong pollution (P15) for Ag and low pollution (P11) for Zn and Pb. Heavy pollution (NIPI3) in Effurun-Sapele road and Ekpan dusts was attributed to heavy metals. ERI revealed moderate risk for heavy metals in Igbudu market dusts and Pessu soils while other locations had low risks. Non-carcinogenic health risk evaluation showed HQs greater than 1.0 for V, Cr, Mn, Fe, Co, Cu, Zn, Pb, As, Al and Ca, signifying adverse health effects. The CRs of As, Cr, Cd, Ni and Co for children and; Cr and Co for adults were higher than the acceptable limit of 1.0×10⁻⁴, suggesting probable development of cancer. CONCLUSIONS:This study established the occurrence of dust and soil pollution by chemical contaminants from industrial emissions, vehicular sources and open-dumping. The chemical element concentrations pose carcinogenic and non-carcinogenic risks to children and adult residents of the study area. KEYWORDS: Chemical exposures, Heavy metals, Risk assessment, Cancer and cancer precursors, Children's environmental health