Grey goo on the skin? Nanotechnology, cosmetic and sunscreen safety

Many modern cosmetic or sunscreen products contain nano-sized components. Nanoemulsions are transparent and have unique tactile and texture properties; nanocapsule, nanosome, noisome, or liposome formulations contain small vesicles (range: 50 to 5000 nm) consisting of traditional cosmetic materials that protect light- or oxygen-sensitive cosmetic ingredients. Transdermal delivery and cosmetic research suggests that vesicle materials may penetrate the stratum corneum (SC) of the human skin, but not into living skin. Depending on the physical/chemical properties of the ingredient and the formulation, nano-sized formulations may enhance or reduce skin penetration, albeit at a limited rate. Modern sunscreens contain insoluble titanium dioxide (TiO2) or zinc oxide (ZnO) nanoparticles (NP), which are colorless and reflect/scatter ultraviolet (UV) more efficiently than larger particles. Most available theoretical and experimental evidence suggests that insoluble NP do not penetrate into or through normal as well as compromised human skin. Oral and topical toxicity data suggest that TiO2 and ZnO NP have low systemic toxicity and are well tolerated on the skin. In vitro cytotoxicity, genotoxicity, and photogenotoxicity studies on TiO2 or other insoluble NP reporting uptake by cells, oxidative cell damage, or genotoxicity should be interpreted with caution, since such toxicities may be secondary to phagocytosis of mammalian cells exposed to high concentrations of insoluble particles. Caution needs to be exercised concerning topical exposure to other NP that either have characteristics enabling some skin penetration and/or have inherently toxic constituents. Studies on wear debris particles from surgical implants and other toxicity studies on insoluble particles support the traditional toxicology view that the hazard of small particles is mainly defined by the intrinsic toxicity of particles, as distinct from their particle size. There is little evidence supporting the principle that smaller particles have greater effects on the skin or other tissues or produce novel toxicities relative to micro-sized materials. Overall, the current weight of evidence suggests that nano-materials such as nano-sized vesicles or TiO2 and ZnO nanoparticles currently used in cosmetic preparations or sunscreens pose no risk to human skin or human health, although other NP may have properties that warrant safety evaluation on a case-by-case basis before human use

Safety and Toxicity Counts of Nanocosmetics

The advent of nanotechnology has led to advances in the cosmetic industry and is expected to grow further in the near future. Nanotechnology-driven products cater to the expectations of both consumers and manufactures in terms of better quality and effectiveness along with improved stability and easy scale-up. Several organic and inorganic materials are being utilized for the preparation of nanocosmetics having improved characteristics. At the same time, the safety aspects of nanocosmetics are also being pondered. Physicochemical properties play a significant role in controlling the toxicity of nanomaterials. Several mechanisms have been studied for nanomaterial generated toxicity; out of all, reactive oxygen species, generation is the most important mechanism. This chapter discusses all the relevant aspects which are required for safety and toxicity assessments of nano-ingredients for cosmetic use. Regulatory issues are also discussed because of their relevance in preventing the unforeseen toxicity of nanocosmetics