Health risk assessments of heavy metals in dust samples collected from classrooms in Ilorin, Nigeria and its impact on public health

Abstract

Over the past three decades, heavy metals (HMs) in indoor dust have been a significant focus due to their environmental and health risks. This study assessed HM contamination (Co, Pb, Cd, Cr, Ni, and As) in classroom and lecture theatre dust in Ilorin, Nigeria, across dry and rainy seasons. Dust samples from primary, secondary, and university settings were analyzed using atomic absorption spectrometry and ICP-OES. HM concentrations followed the order As > Pb > Co > Cr > Ni > Cd, all below background values. Indices like geoaccumulation (Igeo), contamination factor (CF), and pollution load index (PLI) indicated minimal contamination. The proportion of human health risks attributed to dermal contact, represented by HQderm and CRderm, accounted for 67.76 % and 30.30 % of the total hazard index (HI) and cancer risk (CR) during the dry season, and 86.76 % and 72.65 % during the rainy season, respectively. Health risks via ingestion, inhalation, and dermal exposure showed children were more vulnerable than adults, with dermal pathways contributing significantly to overall risk. Principal component and geo-spatial analyses highlighted natural and anthropogenic HM sources. The findings provide critical data for policymakers to develop effective strategies for minimizing HM exposure in indoor environments.