Contents lists available at ScienceDirect Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv Characterization of metals in indoor dusts from electronic workshops, cybercafés and offices in southern Nigeria: Implications for on-site human exposure Chukwujindu M.A. Iwegbue a, ⁎ , Grace Obi b , Onoriode O. Emoyan a , Eze W. Odali a , Francis E. Egobueze c , Godswill O. Tesi a , Godwin E. Nwajei a , Bice S. Martincigh d a Department of Chemistry, Delta State University, P.M.B. 1, Abraka, Delta State, Nigeria b Department of Chemistry, Federal University of Petroleum Resources, Efurrun, Delta State, Nigeria c Environment and Quality Control Department, Nigerian Agip Oil Company, Port Harcourt, Nigeria d School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa ARTICLE INFO Keywords: Metals Indoor dust Health risks Nigeria ABSTRACT The levels of Cd, Pb, Cr, Ni, Cu, Co, Ba, Mn, Zn, Al and Fe were evaluated in indoor dusts from electronic workshops, cybercafés and offices in southern Nigeria. The study was aimed at providing information on the distribution patterns, and the associated risks that may arise from exposure of humans to these metals in indoor dusts from the three work environments. The dust samples were digested with aqua-regia and analyzed for the metal concentrations by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The metal con- centrations (mg kg -1 ) in the indoor dusts from these work environments ranged from 0.2 to 20.5 Cd, 0.6–4810 Pb, 8.65–2210 Cr, 1.85–209 Ni, 6.75–2820 Cu, 0.25–19.6 Co, 22.7–597 Mn, 6.65–140 Ba, 43.3–7310 Zn, 1040–16,800 Al and 969–78,300 Fe. The metal distribution patterns in these dust samples followed the order: electronic workshops > cybercafés > offices. The concentrations of Cd, Pb and Cu in significant proportions of the dust samples from the electronic workshops and cybercafés surpassed their respective permissible limits in soils. The health risk assessment suggests considerable non-cancer risks arising from childhood contact with Pb in dust from the electronic workshops while no considerable non-cancer risk is associated with the adult and child exposure to dust from the cybercafés and offices. The results indicated that Cr and Pb are the main elements responsible for the non-carcinogenic risk arising from childhood exposure to electronic workshop dusts. The carcinogenic risk due to exposure of humans to metals in these dust samples were within the range regarded as safe by the USEPA. 1. Introduction Contamination of indoor environments by metal-laden dust parti- cles is a serious concern since metals are persistent and bio-accumula- tive pollutants. Human exposure to high concentrations of metals can cause deleterious and irreversible health effects because a number of them can accumulate in the fatty tissues of humans, affect the re- productive, renal, respiratory, circulatory and central nervous systems, and cause internal organ dysfunction. For example, Pb can induce ir- reversible neurological damage, developmental and behavioural dis- orders, especially in children, while Cd and Pb can also disrupt im- portant nuclear functions including DNA repair and replication, and gene expression via inhibition of nuclear uptake, homeostasis and the functions of essential metal ions (Menzie et al., 2009; Hassan, 2012). There is convincing evidence that metals are discharged into the en- vironment from primitive e-waste processing and recycling activities (Wong et al., 2007) since elevated concentrations were found in en- vironmental matrices (air, dust, plants, soil and sediments) close to e- waste recycling sites (Song and Li, 2014). Indoor dust represents an important source of toxicant exposure for the general population, and especially young children. It serves as a sink and storehouse for metals, toxic organic compounds such as PAHs, PBDEs, PCBs, dioxins, bisphenols and phthalates, and particle-bound matter. Trace elements are significantly enriched in indoor environ- ments in comparison with their outdoor abundances (Rasmussen, 2004). The concentrations and types of metals in indoor environments are influenced by the nature of outdoor activities such as industrial and traffic emissions, and the nature of the indoor settings and the activities https://doi.org/10.1016/j.ecoenv.2018.04.070 Received 4 December 2017; Received in revised form 28 April 2018; Accepted 30 April 2018 ⁎ Corresponding author. E-mail address: cmaiwegbue@delsu.edu.ng (C.M.A. Iwegbue). Ecotoxicology and Environmental Safety 159 (2018) 342–353 Available online 21 May 2018 0147-6513/ © 2018 Elsevier Inc. All rights reserved. T