OSAGIE FERDINAND AMAYO

This study was designed to assess the presence and levels of selected heavy metals, polycyclic aromatic hydrocarbons (PAHs), and microbes in bank note dust as well as their potential health risks. Two commercial banks (Location A, Ekehuan Road, located in Oredo Local Government Area, and Location B, Ugbowo, University of Benin Campus in Ovia North-East Local Government Area) were selected within Benin City metropolis and banknote dust from the counting rooms were collected. The samples were extracted using wet digestion for heavy metals concentrations and solvent (hexane) extraction for the PAHs. The extracted samples were cleaned up and the concentrations determined using an atomic absorption spectrophotometer, AAS (Buck Scientific, VGP210) and gas chromatograph fitted with flame ionization detector (GC-FID) were used to determine heavy metals and PAHs respectively. Particle size determination was carried out by using the dynamic light scattering (DLS) techniques based onBrownian movement principles. Results obtained revealed that the sizes of the dust particles were in the range of 36.57 nm and 48.48 nm which the nano range (0-100 nm). The results of heavy metal analysis revealed that the concentration of iron was the highest value for both locations A (2,055 ± 70.06 mg/kg) and B (1,934.53 ± 68.64 mg/kg). This result is below standard (10,000 mg/kg) set by WHO/USEPA. While cadmium was the lowest concentration of 1.82 ± 0.30 mg/kg and 0.95 ± 0.15 mg/kg for locations A and B respectively, exceeding the permissible limit of 0.8 mg/kg for cadmium as set by WHO. Copper for locations A and B were found to be 56.06 ± 2.53 mg/kg and 50.56 ± 4.42 mg/kg respectively exceeding limit of 36.0 mg/kg standard set by WHO. The concentrations of the heavy metals were found to follow the order: Fe ˃ Zn ˃ Mn ˃ Cr ˃ Cu ˃ Ni ˃ Pb ˃ Cd for location A and Fe ˃ Zn ˃ Mn ˃ Cu ˃ Cr ˃ Ni ˃ Pb ˃ Cd for location B with location A having higher concentration of Cr than location B. PAHs results revealed that all 16 EPA priority PAHs as specified by WHO/USEPA were detected in the banknote dust samples from the two locations. Location A had the highest PAHs summation of 4.278 µg/kg with pyrene alone contributing 3.084 µg/kg, while for location B, phenanthrene was the highest with a value of 1.167 µg/kg. The diagnostic ratio suggests multi-sources ranging from petrogenic to pyrogenic, traffic to non-traffic emissions, coal and wood combustion. Microbial analysis revealed significant loads of bacteria with 1.2 x 104 cfu and 1.1 x 104 cfu obtained from locations A and B respectively while the fungi load was found to be x 2.0 x 104 cfu and 1.1 x 104 cfu for locations A and B respectively. The bacteria identified was streptococcus spp while the fungi were aspergillus and penicillium. This study clearly indicated the potential health risk faced by bank staff especially those in the cash processing units due to long exposure to banknote dust and it is recommended that regulatory bodies monitor human exposure to these pollutants and adequate personal protective equipment (PPE) be made available to staff working in these sections of the banks.