Heavy metal health risk assessment of cow’s milk from an industrialized area of Dhaka, Bangladesh

Abstract The objective of this study was to evaluate the contamination level of toxic and essential metals in milk samples with varying lactation periods (1 to 5 years) near an industrial area on the bank of Buriganga River, Dhaka, Bangladesh. Milk samples were collected and analyzed for 6 toxic metals (Cr, Ni, Pb, Hg, Cd, and As) and 5 essential (Ca, Fe, Zn, Mn, and Cu) by using wet digestion and atomic absorption spectroscopy. In this study, maximum metal contamination was detected for Ca, followed by Fe > Cr > Zn > Mn > Cu > Ni > Pb > Hg > Cd > As. The concentration of Fe, Cr, Ni, Pb, and Hg exceeded their respective national and international reference value. The potential health risk for milk consumption was investigated by estimating various exposure indices including; daily intake (EDI), Target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR). The THQ  1 suggested that there might be health risk due to milk consumption. Long-time consumption of those milk samples may raise the carcinogenic risk in terms of TCR values as the TCR values of Cr, Ni, and As were obtained much higher for average consumers which exceed the maximum permeable limit (1.0×10− 6).