Determination of heavy metals and hydroquinone in skin- Lightening products sold in botswana

Abstract

The use of skin lightening products is a common practice among some groups of people around the world who perceive fair skin color as a feature of superiority and beauty. The use of these products poses a health hazard to people who use them. Cosmetic samples were acid-digested in a microwave digester using USEPA method 301 before analysis for Pb, As, Cr and Ni using inductively coupled plasma optical spectrometer (ICP-OES). Method validations were performed using accuracy, precision, linearity, limits of detection (LOD) and quantification (LOQ). Percent recoveries of 96-105% were achieved and %RSD for both inter-day and intra-day precisions were less than 2%. The LOD and LOQ for the analyzed metals were 0.0063mg/kg and 0.0209 mg/kg for Ni, 0.0256 mg/kg and 0.0853 mg/kg for Pb,0.0932 mg/kg and 0.3105 mg/kg for As and 0.0015 mg/kg and 0.0050 mg/kg for Cr respectively. The concentrations for Pb, Ni, As and Cr were 45.75± 0.10 mg/kg-193.60 ± 3.58 mg/kg, 2.99 ±0.09 mg/kg-9.50 ± 0.45 mg/kg, 1.95 ±0.23 mg/kg-4.52 ±0.22 mg/kg, and 3.32 ±0.05 mg/kg-7.41±0.14 mg/kg respectively. Concentrations of arsenic were below 10 mg/kg. It is worth noting that the concentrations of Pb, Cr, and Ni were above the US FDA set limits of 10 mg/kg,5 mg/kg and 5 mg/kg respectively for some of the analyzed samples. Health risk assessment was performed for heavy metals and the computed ADI concentrations for Pb, As, Cr and Nic were found to be 0.85, 0.024, 0.034 and 0.047 respectively. The hazard quotient for Pb, 64.3% and 35.7% of samples with Ni and Cr respectively were greater than 1. The health risk index was greater than 1 for Pb, As and Ni while for Cr it was less than 1. Pb recorded the highest value of DDE than other heavy metals. This indicates that there is a potential adverse health effect. Sixteen cosmetic products were also analyzed for hydroquinone using high-performance liquid chromatography (HPLC) equipped with ODS C18 column (4.6*250 mm, 5μm, the flow rate of 1.0mL/min, DAD detector(λ=292nm) and injection volume of 20μL. Hydroquinone was detected in four samples and the concentrations ranged between 0.067-7.65%. Out of sixteen cosmetic products analyzed only two contained hydroquinone above the set limit by the US FDA of 2 %. The occurrence of elevated concentrations of heavy metals and hydroquinone in cosmetics products sold in the Botswana market should be strictly controlled and legislative measures should be instituted that prohibit the importation of such products.