Environmental and health risks of metal-contaminated soil in the former tannery area of Hazaribagh, Dhaka
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Environmental and health risks of metal‑contaminated soil in the former tannery area of Hazaribagh, Dhaka Al‑Mizan1 · Md Ariful Islam Juel1,2 · Md Shahin Alam3 · John Pichtel3 · Tanvir Ahmed4 Received: 9 July 2020 / Accepted: 13 October 2020 © Springer Nature Switzerland AG 2020
Abstract Soil and plant samples collected from Hazaribagh, the former tannery area in Dhaka, Bangladesh, were analyzed for heavy metals (Cr, Pb, Ni, Zn, Cd, and Cu). The pollution and health risks of the metals were assessed with commonly used indicators. The mean soil Cr concentration was 4321 mg/kg (range 294–23,148 mg/kg). Most sites had a moderate to high degree of contamination and were classified as extremely polluted (Pollution Load Index > 1). The non-carcinogenic hazard index was greater than 1 for Pb and Cr for both children and adults, which indicates considerable non-cancer health risk. The combined cancer risks for Pb and Cr exceeded the allowable range of 1 × 10−6–1 × 10−4 for most sites (8 out of 11 sites in the case of adults, all sites in the case of children) with Cr being the dominant contributor and oral ingestion the primary pathway. The cancer and non-cancer risks for children were 26- and 3-fold higher, respectively, than for adults. Among all heavy metals, Pb and Zn were the most susceptible to leaching and becoming mobilized in groundwater. Concentrations of Pb, Cr, and Zn in edible parts of vine spinach (Basella alba) exceeded safe limits. However, Pb and Cu showed significant accumulation in plants (Mean Transfer Factor of 1.064 and 0.94, respectively, for Pb and Cu), while Cr exhibited relatively lower bioavailability. The spatial distribution of heavy metal contamination and associated risks presented in this study will allow policymakers to pinpoint areas of intervention for remediation. Keywords Cancer risk · Chromium · Non-carcinogenic risk · Risk assessment · Soil pollution
1 Introduction Heavy metal contamination of soil is a significant hazard and can impart adverse impacts on human health and the environment [1, 2]. Both natural and anthropogenic sources contribute to heavy metal pollution [3, 4]. Natural sources such as volcanic eruptions and weathering of rocks enrich and mobilize heavy metals on the earth’s surface. However, anthropogenic activities, especially over the past few decades, have been documented as the key contributor to increased concentrations of heavy metals in soil and water. Chemical industries, tanneries, mining and smelting, iron and steel industries, agriculture, waste
disposal, battery recycling and oil refining have been responsible for emissions of heavy metals to various environmental compartments [5–10]. In Bangladesh, tannery industries have been at the forefront of environmental pollution for decades. The hub of tanning industries was established in Hazaribagh, Dhaka, about 70 years ago, prior to establishment of relevant environmental regulations. Approximately 185 tanneries operated in the area, which discharged untreated liquid effluent and generated hazardous solid
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