Heavy metal content and antimicrobial activities of some Naturally occurring facial cosmetics in Nigeria
Cosmetics are products, chemical or natural applied to the face or body to improve appearance. However, concern for our physical appearance must be balanced with finding conscientious means by which to care for our skin and our health in general. Naturally occurring facial cosmetic samples (calabash stone and black antimony) were assessed for their heavy metal contents and antibacterial activities. The samples were digested using aqua regia (HNO3 and HCl). The digested samples were analyzed for lead, cadmium, chromium and zinc using atomic absorption spectrophotometer (AAS) Perkin Elmer Analyst 200. The cosmetics were screened against selected Gram positive and Gram negative bacteria using agar broth diffusion assay. Calabash chalk is relatively safer to use compared to black antimony which has higher concentrations of the metals investigated. The range of the geometric mean for the cosmetics samples were found to be: Pb, 3.74-171.14μg/g; Cd, 0.10-0.56 μg/g; Cr, 0.39-7.69 μg/g; and Zn, 0.07-251.60μg/g. Zinc and Lead were high in black antimony. Calabash chalk possessed moderate antibacterial activities against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes but showed no bioactivity against Pseudomonas aeruginosa. Black antimony, however, showed considerable antibacterial activity even against P. aeruginosa. These cosmetics when used continuously, entirely or as additives in cosmetic or personal care products will expose users to low level metal poisoning. Bioccumulation of the metals may lead to deleterious human health effects. The use of black antimony as cosmetics should be discouraged because of the high content of lead and cadmium. Further study to explore the potential antibacterial activity of the cosmetics materials is suggested.
Key words: Heavy Metals, Lead, Cadmium, Cosmetics, Antibacterial, Health Effects