Nanomaterials in Personal Care: Opportunities and Safety Considerations

By: Julian Hewitt and Mindy Goldstein, PhD

Posted: November 26, 2008, from the December 2008 issue of Cosmetics & Toiletries.

From the column editor: Scientists are finding that particles so tiny they are barely there—nanoparticles, which have found homes in electronics, food containers, sunscreens and a variety of other applications—can breech our most personal protective barrier, the skin. Nanotechnology is a broad term, covering the building of structures and machines on an atomic or molecular scale-in the range of 1 to 100 nanometers (nm). The big issue is the behavior of substances at the nano-scale level. A substance at 500 nm can have drastically different properties than the same substance at 10 nm. The emerging field of nanotechnology involves scientists from many different disciplines, including physicists, chemists, engineers and biologists. In recent years, nanotechnology has found beneficial use in medicine, electronics, clinical laboratory analysis, imaging and therapeutics.

This month, I welcome Julian Hewitt, technical specialist for Croda Suncare & Biopolymers, to present an overview of nanotechnology with a focus on sun care. Hewitt graduated from Oxford University in 1988 with a degree in chemistry after which he joined Tioxide, working on new product development. In 1991, he joined Tioxide's Solaveil Business as the applications research and technical service manager for physical sunscreen products. He has remained with the Solaveil business as it moved to ICI Performance Chemicals, Uniqema, and finally Croda. Hewitt has presented papers and posters at more than 30 conferences and has written or co-authored more than 20 articles and four book chapters on formulating sunscreens and in vitro SPF testing.

What is Nanotechnology?
There is much excitement, and controversy, in the world these days regarding nanotechnology. Advocates point to the seemingly limitless array of applications and advantages of nano-scale materials, while at the opposite end of the spectrum, there are those who fear the headlong rush into a frightening new field without properly evaluating potential risks to human health and the environment.

Products that use or claim to use nanotechnology are emerging in many different markets. The Nanotechnology Consumer Products Inventory,¹ an online database from the Project on Emerging Nanotechnologies, lists more than 600 consumer products in categories as diverse as electronics, toys, household appliances, clothing, cleaning products, pet care, food and personal care.

So what exactly is nanotechnology and what are its applications in cosmetics and personal care? Nanotechnology is one of those terms that most think they understand—in the scientific community, at least—but for which most would struggle to provide a precise definition. This may be because there is no official, globally recognized definition of the term; it is, however, generally accepted that nano-scale substances are smaller than 100 nm. This is where the physical and/or chemical properties of the material are significantly different than the larger size or bulk versions of the same material. A current draft definition from the German Standards Institute (DIN) and the International Standards Organization defines the following:

• Nano-object: An object having one or more dimensions (i.e., length, width or thickness) on the nano-scale;
• Nanoparticle: An object having three external dimensions on the nano-scale;
• Nanorod: An object having two external dimensions on the nano-scale; and
• Nanoplate: An object having one external dimension on the nano-scale.