Estimation of Pollution Levels and Assessment of Human Health Risks from Potentially Toxic Metals in Road Dust in Mymensingh City of Bangladesh

Abstract

The assessment of toxic metals pollution in road dust in Mymensingh city, Bangladesh and its impact on the health risk of human exposure to toxic metals, is inadequate. A comprehensive investigation was conducted in different land use areas, i.e., commercial areas (CA), medically facilitated areas (MFA), residential areas (RA), and park areas (PA), to determine levels of Cr (chromium), Mn (manganese), Ni (nickel), Co (cobalt), Cu (copper), Zn (zinc), As (arsenic), Cd (cadmium), and Pb (lead) using inductively coupled plasma mass spectroscopy (ICP-MS). We planned to use different pollution indices, such as the geoaccumulation index (Igeo), contamination factor (CF), degree of contamination (Cdeg), ecological risk (Er), pollution load index (PLI), and enrichment factor (EF), to measure the level of contamination in the road dust of Mymensingh City. The average concentration (mg/kg) ranges of toxic metals in the road dust at different land use areas of Mymensingh City were: Cr (40.8–85.5), Mn (370.7–589.2), Co (6.2–8.7), Ni (22.7–34.2), Cu (29.5–72.2), Zn (236.2–467.1), As (4.9–6.29), Cd (0.32–1.07), and Pb (27.4–81.7), respectively. The CF and PLI results showed that the road dust in these zones was contaminated with toxic metals. The indicator Igeo revealed that CA was found to be ‘moderately to heavily contaminated’ ranked with Zn and Cd. Calculation of EF indicated that Cu, Zn, As, Cd, and Pb were highly enriched, while others were moderately enriched. According to the Cdeg findings, CA, MFA, and RA have very high degrees of contamination (Cdeg ≥ 24), while PA was classified as having a considerable degree of contamination (12 ≤ Cdeg < 24). The Er index showed that only Cd posed a ‘medium potential ecological risk’ to a ‘high ecological potential risk’ in road dust. The most common route of exposure was ingestion. The study indicated that the hazard quotient (HQ) and hazard index (HI) in CA, MFA, RA, and PA were less than one for children and adults, which were at a noncarcinogenic risk. The only exception was for children exposed to manganese (HI > 1) in all land use areas. In the research area, no significant carcinogenic health risk was observed for Cr, Ni, As, Cd, and Pb.