Human and ecological risks of metals in soils under different land-use types in an urban environment of Bangladesh

Trace metal contamination in soil is of great concern owing to its long persistence in the environment and toxicity to humans and other organisms. Concentrations of six potentially toxic trace metals, Cr, Ni, Cu, As, Cd, and Pb, in urban soils were measured in Dhaka City, Bangladesh. Soils from different land-use types, namely, agricultural field, park, playground, petrol station, metal workshop, brick field, burning sites, disposal sites of household waste, garment waste, electronic waste, and tannery wast, and construction waste demolishing sites, were investigated. The concentration ranges of Cr, Ni, Cu, As, Pb, and Cd in soils were 2.4-1 258, 8.3-1 044, 9.7-823, 8.7-277, 1.8-80, and 13-842 mg kg^-1, respectively. The concentrations of metals were subsequently used to establish hazard quotients (HQs) for the adult population. The metal HQs decreased in the order of As > Cr > Pb > Cd > Ni > Cu. Ingestion was the most vital exposure pathway of studied metals from soils followed by dermal contact and inhalation. The range of pollution load index (PLI) was 0.96-17, indicating severe contamination of soil by trace metals. Considering the comprehensive potential ecological risk (PER), soils from all land-use types showed considerable to very high ecological risks. The findings of this study revealed that in the urban area studied, soils of some land-use types were severely contaminated with trace metals. Thus, it is suggested that more attention should be paid to the potential health risks to the local inhabitants and ecological risk to the surrounding ecosystems.