Assessment of Heavy Metals and Polycyclic Aromatic Hydrocarbons in Nanoparticulate Banknote Dust from Selected Commercial Banks in Benin Metropolis, Nigeria

Abstract

The improper handling of banknotes can accumulate dust that carries pollutants, posing health risks. This study assesses the potential health risk of particulate banknote dust (BND) in two commercial banks (A and B) in Benin Metropolis, Nigeria. About 10 g of BND were collected twice from each bank's tables and equipment with a soft brush and stored in airtight bags. The samples were analyzed for heavy metals using atomic absorption spectrophotometry (AAS), and polycyclic aromatic hydrocarbons (PAHs) using gas chromatography with a flame ionization detector (GC-FID), and the particle size was measured via dynamic light scattering (DLS). The results obtained for particle size ranged from 36.57 to 48.48 nm, indicating a nano-sized nature. The results of heavy metal concentration showed that iron had the highest, at 2,055.00 ± 70.06 mg/kg for location A and 1,934.53 ± 68.64 mg/kg for location B; however, both locations were below WHO/USEPA limits of 10000 mg/kg. Cadmium was recorded as the lowest in locations A (1.82 ± 0.03 mg/kg) and B (0.95 ± 0.15 mg/kg), exceeding permissible limits of 0.8 mg/kg. All 16 EPA priority PAHs were detected in the BND, with location A showing the highest concentration at 4.278 µg/kg, dominated by pyrene, and location B having more phenanthrene. These findings suggest possible health risks for staff and customers from long-term exposure. Therefore, implementing cashless payments and use of personal protective equipment (PPE) for bank staff is recommended.