Abstract:
Titanium (IV) oxide (TiO2) is used as a physical blocker of ultraviolet (UV) radiation in many skin-care
products. Absorption of TiO2 through the skin is likely to interact with viable tissues because UV radiation
absorption generates toxic reactive oxygen species such as hydroxyl radicals. Studies on the acute toxicity of
TiO2 nanoparticles in mammals indicate that intra-tracheal instillation, intraperitoneal injection or oral
instillation of TiO2 particles to the animals evoke an inflammatory response as well as certain histopathological
changes. Ultrafine particles of the anatase form of titanium (IV) oxide, which are smaller than 0.1 microns, are
pathogenic. In this work eight skin-lighteners containing TiO2 from South African market were studied. The
TiO2 was extracted by a fusion technique and quantified by inductively coupled plasma-optical emission
spectrometry (ICP-OES). Sequential solvent extraction was employed to isolate TiO2 particles for
characterization employing high-resolution transmission electron microscopy (HR-TEM) and powder X-ray
diffraction (PXRD). All samples considered in this study meet agreeable TiO2 % (m/m) levels as specified by all
health regulatory bodies. Both forms of TiO2: anatase and rutile, were found to be present. Most samples
contained nano-TiO2 in the particle size range of 16.23 nm to 51.47 nm that could lead to detrimental effects.
The fact that the anatase form, known for its photocatalytic activity, was present, is a cause for concern.
