Determination of Some Heavy Metals in Selected Beauty and African Black Soaps Commonly Used in Kano – Nigeria

Abstract

Several epidemiologic studies have investigated the potential carcinogenicity of human exposure to heavy metals from diverse sources but few or none was on African black and beauty soaps. Hence, this study examines the presence of some heavy metals in selected African black and beauty soaps commonly used in Kano- Nigeria, with a view to seeing whether solutions could be found in preventing or minimizing dermal infections/problems caused due to exposure to these metals. Different African black and beauty soap samples were purchased from retail outlets and open markets in Kano metropolis. The samples were oven-dried to constant weight at 80oC for12hrs in the laboratory. 0.2g of the dried samples were digested with a mixture of H₂SO₄, HNO₃ and HCl (5:5:1 ratio) and analyzed for Ni, Cu, Fe, Co, Pb and Mn contents using air-acetylene flame atomic absorption spectrophotometer (Alpha 4) model by the standard calibration technique. From the study it has been noted that, the level of the metals are in the order Mn (0.532)> Fe (0.467)>Ni (0.432μg/g)>Pb (0.403μg/g)> Co (0.272μg/g)>Cu (0.241μg/g) in the beauty soaps, while in the African black soaps, the order is;Cu (0.852μg/g)> Ni (0.578μg/g)>Pb (0.481μg/g)> Fe (0.316μg/g)> Co (0.310μg/g) >Mn (0.250μg/g).There were no limit values for heavy metals in soaps by the regulations relating to consumer care products with which the values from this study could be compared with; hence it is difficult to ascertain if the values are high or low. But when the values are compared with the exposure limits of the metals in air as set out by EPA (1.5μg/L Pb, 1mg/m³Ni, 0.1mg/L Co and 0.05μg/m³Mn), the mean values of the metals Pb and Ni in both the Beauty and African Black Soaps are below the EPA limits while Co and Mn are above the limits.

Keywords: African Black Soap, Beauty Soap, Hazardous Substances, Heavy Metals