Characterising and communicating the potential hazard posed by potentially toxic elements (PTEs) in indoor dusts from schools across Lagos, Nigeria.

Famuyiwa, Abimbola and Entwistle, Jane (2021) Characterising and communicating the potential hazard posed by potentially toxic elements (PTEs) in indoor dusts from schools across Lagos, Nigeria. Environmental Sciences: Processes and Impacts, 23 (6). pp. 867-879. ISSN 2050-7887

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Abstract

Ambient and indoor air pollution results in an estimated 7 million premature deaths globally each year, representing a major contemporary public health challenge, but one poorly quantified from a toxicological and source perspective. In rapidly growing cities, such as Lagos, Nigeria, environmental monitoring can play an important role in establishing baseline data, monitoring urban pollution trends and in environmental education. Classroom dust samples were collected from 40 locations from across the twenty local government areas (LGAs) of Lagos, in June 2019. The aim of the study was to assess the potential hazard posed by potentially toxic elements (PTEs) in indoor dusts and to develop a suitable risk communication strategy to inform and educate the public, promoting environmental health literacy. Levels of PTE in indoor dusts was assessed using Energy Dispersive X-ray Fluorescence (ED-XRF) spectrometry (Spectro Xepos Kleve, Germany). Oral bioaccessibility testing was also performed on the dust samples to determine the fraction available for absorption in the gastrointestinal tract. Results showed that the indoor dust samples were largely uncontaminated, with only few exceptions (2 samples). Enrichment factor pollution trend for the PTE studied was in the order of Pb > Zn > U > Cr > Cu > Ba > Mn > V > As > Cd > Ni > Al. Source apportionment studies using factor analysis and cluster analysis suggests concentrations of Al, As, Cr, Fe, Mn, Ni, U and V may be influenced by lithogenic factors while Cd, Cu, Pb originated from anthropogenic sources. Barium and Zn appeared to be emanating from mixed sources of both lithogenic and anthropogenic sources. Oral bioaccessibility studies indicated that the assumption of 100% bioavailability based on pseudototal or total concentrations would overestimate the hazard potential of Cu (36%), As (37%), Al (41 %), Pb (48%), Ba (48%) and Mn (57%). Zinc was the most bioaccessible PTE (mean of 88%), with bioaccessibilityof around 100 % in half of the indoor dust samples studied, suggesting that the simulated UBM gastric solution was as efficient in solubilising Zn as the aqua-regia. Human health risk assessment for both children and adults showed values to be within acceptable risk levels.

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