Safety Evaluation of Metal Exposure From Commonly Used Hair Dyes and Tattoo Inks in Nigeria.

In the study described in this article, the concentrations of metals (cadmium, copper, chromium, aluminum, lead, nickel, zinc, cobalt, manganese, and iron) in samples of some commonly used hair dyes and tattoo inks were determined with a view to providing information on the hazards associated with the use of these products. The concentrations of metals were measured after nitric acid/perchloric acid/hydrogen peroxide digestion by atomic absorption spectrometry. Results indicated that the tattoo ink samples contained allergenic metals such as nickel, chromium, and cobalt at concentrations above the suggested limit of 1 µg/g for greater skin protection, and the toxic metals were below their respective prescribed limits, as impurities in ingredients for use for cosmetics, in the majority of the samples.

Safety evaluation of metal exposure from commonly used moisturizing and skin-lightening creams in Nigeria.

The concentrations of ten metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn and Al) were measured in some commonly used moisturizing and skin-lightening creams in Nigeria with a view to providing information on the risk of exposure to metals from the use of these products. The metal concentrations in these products were measured by atomic absorption spectrometry after acid digestion of the samples. The measured concentrations of metals in the skin moisturizing creams ranged from <0.15 to 6.3 µg/g Cd, <0.02 to 17.5 µg/g Cu, 2.25 to 6.25 µg/g Cr, <0.25 to 124.3 µg/g Al, 0.2 to 7.3 µg/g Pb, <0.03 to 10.7 µg/g Ni, 17.3 to 372.0 µg/g Zn, <0.02 to 1.0 µg/g Co, 17.75 to 28.8 µg/g Mn, <0.1 to 89.8 µg/g Fe while the concentrations of metals in the skin-lightening products ranged from <0.15 to 16.5 µg/g Cd, <0.02 to 10.0 µg/g Cu, 4.25 to 8.0 µg/g Cr, <0.25 to 128.0 µg/g Al, 0.5 to 4.5 µg/g Pb, <0.03 to 1.65 µg/g Ni, 24.7 to 267.5 µg/g Zn, <0.02 to 2.5 µg/g for Co, 19.3 to 31.8 µg/g Mn, 9.5 to 211.63 µg/g Fe. In a significant number (>93%) of the samples investigated the concentrations of Pb, Cd, Ni and Co were below the specified limit, or the maximal limit for impurities in colour additives in cosmetics for external use. However, Cr was found at concentrations above the allergenic limit of 1 µg/g. The results also showed that skin-lightening creams contained higher concentrations of the studied metals than the moisturizing creams, except for Ni, which indicates that persons who uses skin-lightening creams in preference to moisturizing ones, are exposed to higher concentrations of metals.