Pollution indexing and health risk assessments of trace elements in indoor dusts from classrooms, living rooms and offices in Ogun State, Nigeria

Heavy metals are known to have a negative impact on human health especially children through oral ingestion. Total metal concentrations were determined in indoor dust from 19 locations consisting of classrooms, living rooms and offices in Ogun State, Nigeria. Digestion and instrumentation reproducibility were validated using certified reference materials (BCR 723 (Road Dust), NIST 2711a (Montana Soil) and NIST SRM 1640e (Trace element in water)). The measured and certified values showed good agreement. Potential threat levels using geo-accumulation (Igeo) and human health risk for both children and adult were assessed. The mean Igeo levels for the classified and probable carcinogens is in the order Cd (4.84)>Cr (3.28)>Pb (2.61)>Ni(2.48)>As (1.64) while other elements are in the order Zn (5.41)>Ba (4.86)>Sr (4.38)>Zn (4.27)>V (3.24)>Cu (3.14)>Hg (2.61)˜TI (2.61). For human health risk, ingestion was the main route of exposure followed by dermal uptake and inhalation. Hazard index values for all studied metals were lower than the safe level of 1 while Hg vapor exhibited the highest risk value (0.13) in the case of children. The carcinogenic risk for As, Cd, Co, Cr, Ni and Pb were all within the acceptable level (10-4–10-6), but there was potential carcinogenic risk posed by Cr for both adults and children.