Contamination and human health risks of metals in indoor dust from university libraries: A case study from Qingdao, China

Contamination degree and health risks of metals in indoor dust from three university libraries were evaluated. The mean concentrations of Cd, Zn, Cu, Pb, Ni and As in dust were higher than their soil background values. The mean contamination factor (CF) indicated very high contamination of Cd, Zn, and Cu, considerable contamination of Pb, and moderate contamination Ni and As, respectively. The enrichment factor (EF) revealed very severe enrichment of Cd (39.61) and Zn (39.76), severe enrichment of Cu (15.27), moderately severe enrichment of Pb (8.14), moderate enrichment of Ni (3.25), and minor enrichment of As (2.88), Cr (2.30) and Mn (1.38) in the dust. The hazard index showed no significant non-carcinogenic risks of these metals in the dust. The total carcinogenic risk of As from all sites, and of Cd from two sites, were higher than 1 x 10(-6), thereby suggesting the CRs from exposure of As and Cd were not negligible. However, the sum of the TRs did not exceed 1 x 10(-5), indicating the carcinogenic risks are generally acceptable. To conclude, toxic metals in indoor dust from the surveyed libraries may pose potential ecological risks due to high enrichment of Cd, but the health risks are generally acceptable.