Fugitive dust in the vicinity of cement storage facilities as localized sources of toxic metal exposure in Nigerian urban settings: A geochemical health risk assessment.

This study quantified toxic metal concentrations in settled atmospheric dust in the vicinity of cement storage facilities and evaluated associated human health risks in selected Nigerian cities. Dust samples (n = 75) were collected from five active cement depots across Ondo State and Abuja and analyzed for 37 elements using inductively coupled plasma optical emission spectrometry. Human health risks for adults and children were assessed through ingestion, inhalation and dermal exposure pathways following United States Environmental Protection Agency models as a screening-level assessment. Lead concentrations were highest at Igodan Lisa, Okitipupa (726.5 mg/kg), approximately fourteen times higher than levels measured at the lowest site (Weye Police Station, Abuja). Total hazard indices exceeded the safe threshold of 1.0 by over two orders of magnitude for both adults (HI = 137.5) and children (HI = 58.9), indicating substantial non-carcinogenic risk. Inhalation exposure dominated overall risk, accounting for more than 99 % of the average daily dose for chromium, lead and nickel. Estimated cancer risk for children via chromium inhalation reached 5.1 × 10⁻³ , equivalent to one additional cancer case per two hundred exposed individuals and far above the acceptable benchmark of 1 × 10⁻⁶. Principal component analysis suggested mixed industrial and crustal sources, although source attribution remains inferential due to the absence of airborne particulate matter measurements and mineralogical confirmation. These findings identify areas surrounding cement storage facilities as hyper-localized hotspots of toxic metal exposure, though conclusions are constrained by dry-season sampling and reliance on total rather than bioaccessible metal concentrations.