Comparative Environmental and Human Health Risk Assessment of Heavy Metal Contamination near Dhaka’s Tannery Estates

This study studies contamination outlines, pollution causes, and allied health influences in two tannery estate locations in Dhaka, Bangladesh: Hemayetpur, Savar (new) and Hazaribagh (old). Soil and vegetable samples were collected from industrial areas (IA) and residential/agricultural areas (RA). Four heavy metals—chromium (Cr), cadmium (Cd), lead (Pb), and manganese (Mn)—were enumerated using flame-polarized atomic absorption spectrophotometry (AAS). Statistical tools, including pollution indices, bioconcentration factors (BCF), correlation analysis, and principal component analysis (PCA), were applied to assess health risks. Non-carcinogenic and carcinogenic health risks were evaluated according to WHO/FAO guidelines. Heavy metal concentrations in soils (mg/kg) were: Hazaribagh – Cr: 608.53, Cd: 2.89, Pb: 3.59, Mn: 1.81; Hemayetpur – Cr: 745.93, Cd: 2.93, Pb: 35.47, Mn: 3.23. In vegetables, B. alba contained Cr: 219.86, Cd: 7.73, Pb: 5.23, Mn: 0.56; L. siceraria contained Cr: 391.37, Cd: 8.11, Pb: 5.49, Mn: 2.67. Industrial soils exceeded WHO/FAO permissible limits for Cr and Cd by up to 42 and 14 times, respectively. Cr was the dominant pollutant, followed by Cd, Pb, and Mn. Pollution indices indicated severe contamination, particularly in IA-2 (Hemayetpur). Vegetables revealed high Cd BCFs, with root concentrations exceeding safety threshold levels. Dietary exposure was the primary health risk pathway, with Cd posturing the uppermost ecological risk and Cr the highest carcinogenic risk. Industrial activities, primarily tanning and insufficient effluent treatment via the Common Effluent Treatment Plant (CETP), are the major contamination sources (Cr > Cd > Pb). While RA soils exhibited lower contamination, diffuse pollution was apparent.