The prefix ‘nano’ is one of those terms that polarises opinion. Advocates of nanoscale materials point to their many advantages and applications, while on the opposite side are those who feel that nanotechnology per se carries unknown risks to human health and should be avoided at all costs.
A number of different nano-sized components have applications in personal care, for example:
• Nanoemulsions: emulsions with a droplet size of typically 50 nm to 100 nm, which, because of this small droplet size, are usually transparent or at least translucent in appearance and also provide pleasant texture and/or skin feel.
• Liposomes, niosomes, nanosomes and nanocapsules: liposomes and niosomes are globular vesicles which can vary from 25 nm to 5000 nm in size, and are used to encapsulate active ingredients in order to improve stability or skin delivery (and hence efficacy) of these ingredients. Nanocapsules represent a similar concept except that such capsules have rigid walls.
• Fullerenes: a number of prestige cosmetic products have been developed which contain C60 fullerene molecules, which have unique anti-oxidant properties.
• Inorganic particles: nanoscale forms of, for example, iron oxide, silica, and alumina have also found application in cosmetic products.
Of these, the nanoemulsions and the vesicles are designed to break down into their constituent ingredients when applied onto skin or hair, so in terms of assessing risk, these are no different to conventional cosmetic emulsions and delivery systems. Assessing the safety of such systems is simply a matter of considering the safety of the bulk constituents; the fact that they are in a nano form in the formulation is irrelevant. The current debate around nanotechnology in personal care is instead focused on ‘persistent’ nanoparticles, i.e. those that remain in a particulate form after the product has been applied. The most common types of such nanoparticles in personal care products are the UV-attenuating grades of titanium dioxide and zinc oxide, in which a small particle size is required in order to give effective UV protection combined with transparency on skin. This article outlines current thinking regarding the definition and characterisation of nanomaterials in cosmetics, discusses the properties of inorganic sunscreens in relation to these definitions, and examines the safety and regulatory aspects of these materials.
Log in or register FREE to read the rest
This story is Premium Content and is only available to registered users. Please log in at the top of the page to view the full text.
If you don't already have an account, please register with us completely free of charge.
