Assessment of health risks associated with road dusts in major traffic hotspots in Abeokuta metropolis, Ogun state, southwestern Nigeria

摘要

The present study assessed the health risks associated with road dusts in major traffic hotspots and unpaved road sites in Abeokuta metropolis, Ogun State, southwestern Nigeria. Dust samples were collected from forty-seven sites (unpaved and paved roads) between February and March 2015. Three soil samples were also collected from the farmland of the Federal University of Agriculture, Abeokuta, as control. A total of 50 road dust and control soil samples were collected and subjected to laboratory assays using standard procedures. The physical and chemical parameters analyzed were pH, electrical conductivity and metal content (Cu, Zn, Fe, Mn, Pb, Ni, Cd, Cr, V, Ba, Na and K). The health risk indices of non-carcinogenic effects [hazard quotient and hazard index (HI)] and cancer risk of toxic metals in soil/dust samples were assessed. Data were evaluated for descriptive and inferential statistics using the Statistical Package for Social Sciences (SPSS) for Windows package. Results indicated higher significant (p < 0.05) values of Zn at the roadsides (paved = 94.1 +/- 52.1 mg kg(-1), unpaved = 101.5 +/- 69 mg kg(-1)) than control (27.6 +/- 16.5 mg kg(-1)). Pb concentrations of road dusts (paved = 31.8 +/- 33.6 mg kg(-1), unpaved = 50.8 +/- 48.9 mg kg(-1)) were also statistically higher (p < 0.05) than those of control samples (6.33 +/- 3.36 mg kg(-1)). However, Mn was measured at significantly (p < 0.05) higher concentration in control soil than road dust samples. The varimax rotated Principal Component Analysis revealed four major emission sources of metals in both paved and unpaved dust samples. The health risk assessment of metals showed HI values less than 1.0 in adults and greater than 1.0 in children. The health assessment results showed children to be at higher risk of metal exposure in road dust than the adults. The order of CR values for metals in road dusts and control soil follows Cr > Cd > Ni > Pb for adults and children. The CR values of Cr, Cd and Ni in road dusts were higher than the acceptable safe limit of 1.0 x 10(-4) indicating probable carcinogenic adverse effects.