Health risks assessment of heavy metal contamination in drinking water collected from different educational institutions of Khulna city corporation, Bangladesh

Clean and safe drinking water is indispensable for maintaining the sound health of humans. The presence of toxic elements in drinking water may cause harmful health effects. In this study, the concentrations of heavy metals in the drinking water of different academic institutions of the Khulna City Corporation (KCC) were determined using an atomic absorption spectrophotometer (AAS). The human health risks were assessed based on estimated daily intake (EDI), target hazard quotient (THQ), hazardous index (HI), and target cancer risks (TCR). The presence of the investigated heavy metals was in the following ranges: Fe (18.5−861.6 µg/L), Mn (0.020−0.564 µg/L), Zn (8.8−96.1 µg/L), Cu (5.6−52.9 µg/L), and As (<0.5−105.3 µg/L). About 52% of the drinking water samples for Mn and 12% for As surpassed the Bangladesh standard (BDS) value of 50.0 µg/L. On the other hand, the As concentration in 88% of the samples exceeded the guideline value of the World Health Organization (WHO) (10.0 µg/L). The analysis of the Pearson’s correlation matrix (r) showed a positive correlation between Zn−Mn, Cu−Mn, Zn−Fe, Cu−Fe, and Fe−Mn at 0.01 levels and Zn−Cu and Fe−As at 0.05 levels, indicating the same pollution source. However, the THQ values of Zn, Cu, Fe, and Mn in all the studied samples were within the threshold risk limit (THQ < 1.0), and hence, safe from metal toxicity. But the THQ and HI of As for both adults and children and the TCR of As for adults in most of the investigated samples exceeded the maximum risk limit (THQ < 1.0; HI < 1.0; and TCR = 10−4), which revealed As could be a potential source of carcinogenic and non-carcinogenic health risks. Therefore, regular monitoring of heavy metals should be carried out to assure good quality drinking water for the students and academic staff.