Determination of Levels of Heavy Metal in Sub-Soil Around Incinerator in University of Benin Health Centre

Abstract

ABSTRACT

Incineration of medical waste (MW) is an important alternative method for the disposal of this type of hazardous waste. Samples of soil around an incinerator and soil from within the health center were collected from the University of Benin Health Center, and soil samples from Capitol (before UNIBEN Chancellor residence) in the same University of Benin served as the control site. These studies were carried out in Benin City, Edo State, Nigeria, from January 2017 to December 2017. Samples were analyzed for Zn, Pb, Cd, Cr, Fe, and Mn. Samples were collected between 4 pm and 7 pm on Fridays every week for one year. The mean concentrations of heavy metals (Zn, Pb, Cd, Cr, Fe, and Mn) were determined in the samples. Atomic absorption spectrophotometry was used for heavy metal analysis after digestion using standard methods. The results obtained are: 0.467±0.267 mg/kg, 0.033±0.049 mg/kg, 0.003±0.005 mg/kg, 0.725±0.316 mg/kg, 12.476±0.315 mg/kg, and 0.922±0.073 mg/kg for Zn, Pb, Cd, Cr, Fe, and Mn, respectively, for the control site; 0.800±0.374 mg/kg, 0.133±0.098 mg/kg, 0.133±0.098 mg/kg, 1.619±0.737 mg/kg, 23.467±0.861 mg/kg, and 2.465±0.295 mg/kg for Zn, Pb, Cd, Cr, Fe, and Mn, respectively, for the health center; and 1.135±0.281 mg/kg, 0.242±0.162 mg/kg, 0.023±0.036 mg/kg, 2.118±0.881 mg/kg, 26.258±1.200 mg/kg, and 2.465±0.295 mg/kg for Zn, Pb, Cd, Cr, Fe, and Mn, respectively, for the incinerator site. Data obtained were analyzed using ANOVA. A probability value of ≤ 0.05 was considered significant. P-values at (probability ≤ 0.05) were Zn = 4.2E-09, Pb = 0.007809, Cd = 0.21624, Cr = 1.05E-07, Fe = 1.13E-23, and Mn = 1.44E-15; except for Pb and Cd, all others listed were less than 0.001. This indicates that the various sites/locations have a significant effect on the mean concentrations of the heavy metals. For Pb and Cd, the various sites/locations had no effect on their mean concentrations. The results from the sites/locations were higher than the control site, indicating a clear case of pollution. Comparison of heavy metal concentrations in soil with WHO maximum allowed limits showed that they are all below the set limits. The soils at the adopted medical incinerator had higher concentrations of heavy metals than the soils around the health center. Medical waste, when not properly disposed of, poses a serious threat to public health and should be disposed of appropriately.