Indoor settled harmattan dusts at seven sampling stations from the University of Agriculture Makurdi were collected between November, 2014 to March, 2015 (five months) using the wipe sampling methodology. Gravimetric measurement of the dust samples from all the sample locations revealed that dust loading within the institution during the period of assessment ranges from 4.475 -6.533 g/m 2 . Masses of indoor settled dust were expectedly higher along high traffic, untarred roads and construction sites as well as in older buildings than others during the period of this study. AAS analysis of the dust samples shows that heavy metal concentrations (mg/kg dry weight) throughout the sampling stations during the period of investigation range from 0.2372 -0.7152 for Cu, 293.6 -884.9 for Fe, 4.265 -68.55 for Mn and 4.239 -42.53 for Zn. The concentrations of all the metals investigated were found to be lower when compared with related values in literature and were within acceptable limits during the period of this study. Pearson correlation matrix also shows positive correlation between the possible metal pairs at 95% level of confidence, indicating a similar source which may be from anthropogenic activities within and outside the area.

The quality of surface and ground water in mining communities is uncertain since metals associated with acid mine drainage are known to saturate these waters. A total of two (2) hand dug wells, two (2) stream water and six (6) mine waste water samples were collected in March 2019. The water samples were analyzed in triplicate for As, Pb, Hg, Cu, Zn, Ni, Cr and Cd using AAS. The toxic metals concentration sequence was such that Pb > Zn >Cu > Cd > Cr > Ni > Hg > As. Pb, Cd and Cr concentrations were higher than WHO and NESREA Standard limits. Measured concentrations of these heavy metals were used to calculate the health risk for human population. The Hazard Index (HI) value for all pathways was found to be 236.8 in mine waste water, 23.39 in stream water 1, 12.91 in stream water 2, 11.1 in well water 1 and 45.07 in well water 2. Among all the studied metals, Cr and Cd has the highest chances of cancer risks with ILCR values of 1.8 x 10 -3 and 5.17 x 10 -3 while Pb and Ni has the lowest chances of cancer risks with ILCR values of 1.69 x 10 -4 and 5.9 x 10 -4 .

ABSTRACT. The aim of this research was to provide an overview of current knowledge, by assessing the possible contamination sources of harvested rainwater by polycyclic aromatic hydrocarbons (PAHs), its effects and possible human health risk assessment. Random sampling technique was used to collect eight rainwater samples from different roofing materials made from (asbestos, zinc, aluminium and thatch) in Warri and Agbarho (AGB). The samples were extracted using a liquid-liquid extraction (LLE) system according to the established procedures of United States Environmental Public Agency (USEPA). Under the optimized conditions, the ranges of extraction recoveries and solid-phase extraction (SPE) clean-up of the PAHs in the harvested rainwater were in the range of 71-90%. Gas chromatography-mass spectrometry (GC-MS) was used for the determination of the sixteen priority PAHs in the samples. The total concentration of PAHs for each of the roof types in Warri Refinery Petrochemical Company (WRPC) are: 0.036±0.012, 0.047±0.020, 0.045±0.018 and 0.0023±0.008 ppm for aluminium, zinc, asbestos and thatch roof, respectively. In addition, total concentration of PAHs for each of the roof types in AGB are: 0.046±0.020, 0.024±0.009, 0.023±0.008 and 0.021±0.007 ppm for aluminium, zinc, asbestos and thatch roof. The PAHs analysed exceeded the United States environmental protection agency (USEPA) standards of contamination.   KEY WORDS: AGB, GC-MS, Harvested Rainwater, LLE, PAHs,  WRPC Bull. Chem. Soc. Ethiop. 2022, 36(4), 779-789.                                                             DOI: https://dx.doi.org/10.4314/bcse.v36i4.5