Bio-Accessibility and Health Risk Assessment of Heavy Metals in Indoor Dust From Higher Institutions in Ondo State, Nigeria

Abstract

Quality of indoor air has been a major concern over time particularly in urban areas. Amidst the indoor air parameters, particulate matter/dust is of core interest owing to the fact that it acts as sediment for metals and other pollutants. Considering the ample amount of time spent indoor by students, this study has been mapped out to investigate the quality of air in tertiary institutions in Ondo State, Nigeria based on their proximity to more anthropogenic activities. Herein, pH, conductivity, and anion concentrations in the indoor dust samples were estimated employing standard analytical methods. Our findings revealed a sequence of anion concentration level as follows, Cl−>SO42−>NO3−. Also, the concentrations of some selected metals were analyzed using flame atomic absorption spectrophotometer (FAAS). The variation in metal concentration observed in most study sites was in the order Cu > Zn > Cr > Pb > Cd. The mean heavy metal variation followed the trend based on the sample collection sites considered in the present study with FE > OA > FU > HT and Cu (0.480mg/kg), Zn (0.409mg/kg), Cr (0.407mg/kg), Pb (0.149mg/kg) and Cd (0.029mg/kg) being the highest concentration of each of the metals. However, all the metal concentrations were below the permissible level. The result from non-carcinogenic study indicates that the average daily dose (by ingestion) was found to be the core exposure pathway such that ADDing > ADDderm > ADDinh. Nevertheless, the hazard quotient (HQ) and hazard index (HI) were less than 1. This implies that no potential health risk. More generally, a relative degree of safety and strict regulations is suggested to be put in place to maintain the status.