Index-based evaluation of pollution characteristics and health risk of potentially toxic metals in schools dust of Shiraz megacity, SW Iran

The concentrations of eight potentially toxic metals (i.e., As, Co, Cr, Cu, Cd, Ni, Pb, and Zn) and their contamination levels in dust collected from some schools of Shiraz city, Iran, have been studied in this work. The pollution of studied metals was assessed using ordinary pollution indices (i.e., PI, I-geo, and EF). The results of calculated pollution load index (PLI) revealed that the contamination status can be more likely attributed to the anthropogenic activities in this region. The results also indicated that traffic and combustion of fossil fuels as well as industrial activities are primary sources that rised heavy metals concentration in school dust. The noncancer risk of individual metals for both children and adults followed the decreasing trend of Pb > Cr > As > Ni > Cd > Cu > Zn > Co and Cr > Pb > As > Cd > Ni > Cu > Zn > Co, respectively. The HI value of Pb and Cr for children is very close to the safety limit, while HI values of other studied metals were fallen in the safe level. In terms of carcinogen risk, Cr, As, and Pb presented in the major of schools were found to be within the cancer threshold limit. However, the cancer risk of exposure to Cd, Ni, and Co was the lowest and could be neglected. The findings indicate that more investigations should be spend on potentially toxic metal contaminations in Shiraz schools, especially for Cr, As, and Pb.