Nanotechnology is an umbrella term referring to the ability to expertly use matter at the atomic, molecular and supramolecular scale (i.e. nanoscale). Nanotechnology holds considerable promise for many different disciplines and it is a growing area of research. At the nanoscale, some materials exhibit additional or different properties as compared to larger materials with the same composition.
Nanomaterials are used in a wide range of innovative applications and products, including Food and Drug Administration (FDA) regulated products such as foods, drugs, medical devices and cosmetics and personal care products. While FDA does not have a legal definition for either nanotechnology or nanomaterials, scientists usually refer to materials that have at least one measured dimension in the range of 1-100 nanometers (1 nanometer = 1 billionth of a meter) as a nanomaterial. To put this into perspective, the head of a pin is about 1 million nanometers wide and a human hair is about 80,000 nanometers wide.
Nanoparticles have been naturally occurring for all of human history. They are found in volcanic ash, ocean spray, fine sand and dust, and are the byproduct of human activities, such as welding fumes and the burning of wood; even homogenized milk is a nanoemulsion. We are constantly exposed to incidental nanoparticles from sources that include cars, your home stove and outdoor fires.
Nanoscale materials are being developed because they can have chemical, physical and biological properties that differ from their chemically identical but larger-scale counterparts. Products containing nanoscale materials may offer advantages over similar products that contain the same materials on a larger scale.
Some of the advantages that have been enabled by the use of nanoscale materials include:
- improved texture
- enhanced stain resistance
- improved aesthetics
- longer shelf life
- improved UV protection
Consumer products that may incorporate nanoscale materials include clothing, wear-resistant coatings and paint, electronics and personal care products.
The application of nanotechnology to products regulated by the FDA, including cosmetics and over-the-counter drugs (OTCs), provides health and other benefits to consumers. The use of nanoscale materials in such consumer products is not new. For example, nanoscale particles of titanium dioxide (TiO2) and zinc oxide (ZnO) have been used in sunscreens for many years.
Remember the old pictures of lifeguards with noses coated in thick white sunscreen? Today, small nanoparticles are used to formulate sunscreens that contain a protective barrier that is easier to apply and has a more pleasing texture than earlier opaque versions with larger particles. This leads to greater consumer acceptance and use. These factors ultimately contribute to a greater public health benefit by protecting individuals from the harmful effects of the sun, including skin aging and skin cancer.
Did you know? Cosmetics manufactured using nanomaterials are subject to the same legal requirements as any other cosmetics.
A number of international expert bodies have finalized their assessments and found nanomaterials are safe for use. For example, the European Union (EU) Scientific Committee on Consumer Safety (SCCS) published their recommendations on the nano forms of ZnO in 2012 and TiO2 in 2013 concluding that both, within certain specified conditions, are safe for use in sunscreens. Similarly, Health Canada revised its sunscreen monograph in 2013 specifically concluding both Nano Zinc Oxide and Nano Titanium Dioxide are permitted ingredients. The Australian Therapeutic Goods Administration in their 2013 opinion reviewed the literature and the work of other international regulatory agencies and again affirmed its 2006 conclusion that neither TiO2 nor ZnO nanoparticles are likely to cause harm when used as ingredients in sunscreens. In 2012 the FDA said it was not aware of any evidence that demonstrates a safety concern from the use of micronized TiO2 in sunscreens. Similarly, FDA stated that available literature indicates nano ZnO, used in sunscreens, does not penetrate into or through human skin to produce adverse health effects when applied topically. Quoting FDA, “In sum, the evidence available does not suggest that use of Ti02 or ZnO nanomaterials in sunscreens presents a public health hazard.” FDA goes further and points out that contrary to the hypothetical risk “The public health benefits of regular sunscreen use are well-established.”
The current risk assessment standard (based on exposure assessment, hazard identification and hazard characterization, followed by risk characterization) in use for conventional chemicals, is also applicable to nanomaterials. However, some methods may need adaptations in view of the distinctive physicochemical characteristics of nanoparticles.
Overall risk characterization of a nanomaterial will not be any different from a conventional cosmetic ingredient. Where a given nanomaterial in a cosmetic product is well-characterized, both from a qualitative and quantitative point of view, and an adequate toxicological dataset is available, there should be no reason to consider that risk characterization of the nanomaterial-containing product is associated with an intrinsically higher uncertainty than that containing conventional ingredients.
The prominent use of micronized/nano materials in personal care products is in sunscreens. The use of nanoscale Titanium Dioxide and Zinc Oxide as active ingredients in OTC sunscreen products is common and has been approved for use by the Food and Drug Administration (FDA) since 1999. Their safety has been extensively evaluated. One detailed review, published by a consortium of scientists in 2010, summarized their safety as follows:
"Based on the current weight of evidence of all available data, the risk for humans from the use of nano-structured titanium dioxide (TiO2) or zinc oxide (ZnO) currently used in cosmetic preparations or sunscreens is considered negligible. There is a large body of information that when viewed in its entirety is considered as sufficient to demonstrate that these nano-structured ultraviolet (UV) filters, irrespective of various treatments (coatings) or crystalline structure, can be regarded as safe for use at concentrations up to 25% in cosmetic products to protect the skin from harmful effects of solar UV radiation.
“Nano” TiO2 and ZnO formulated in topically applied sunscreen products exist as aggregates of primary particles ranging from 30–150 nm in size. These aggregates are bonded such that the force of sunscreen product application onto the skin would have no impact on their structure or result in the release of primary particles. Multiple studies have shown that under exaggerated test conditions neither nano-structured TiO2 nor ZnO penetrates beyond the stratum corneum [surface layers] of skin. Further, the distribution and persistence of these nano-structured metal oxides is the same compared to larger pigment-grade (i.e., >100 nm) particles, demonstrating equivalence in the recognition and elimination of such material from the body. Finally, the in vitro genotoxic and photogenotoxic profiles of these nano-structured metal oxides are of no consequence to human health.
The most logical, straightforward conclusion based on data from internationally-recognized guideline studies and current 20+ year history of human use is that nano-structured TiO2 and ZnO are safe."
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Similar conclusions on the safety of nanoscale Titanium Dioxide and Zinc Oxide have been reached by other expert scientific review groups. In 2013, the EU's SCCS issued its opinion on the safety of TiO2 (nano form) and concluded that at concentrations up to 25% it does not pose any risk of adverse effects in humans after application on healthy, intact or sunburned skin.
The SCCS also reviewed the safety of Zinc Oxide in 2012 and again in 2013 and concluded that ZnO nanomaterial can be considered to pose no or limited risk for use on the skin as UV filters in sunscreen formulations at concentrations up to 25%.
Other nanoscale materials, such as carbon fullerenes (also known as "buckeyballs"), have been reported to be used in some cosmetic products for their beneficial antioxidant properties. However, their use in personal care products is very limited. While there have been some reports that certain chemical forms of fullerenes may produce toxic effects, these effects were observed in studies under exaggerated conditions irrelevant to the human exposure situation. Adverse effects have not been reported following the application of fullerenes in lower concentrations in formulations such as a topically applied lotion or cream. The toxicological potential of such nanoscale materials as fullerenes can be evaluated through current safety evaluation processes, and these materials would only be used in products once their safety was confirmed.
Some products report the use of “nanosomes.” Nanosomes are really small droplets of ingredients that are produced through careful mixing. They have been around for several decades and are also known as “liposomes.” These small droplets, which are capsules containing an outer cover that can be used as a container for other ingredients, are different from nanotechnology as generally understood as they are not stable. When applied to the skin, nanosomes (or liposomes) dissolve and release their contents onto the surface of the skin in the same way as the ingredients in ordinary creams and lotions.
Nanosome/liposome products more effectively deliver moisturizing ingredients to the surface of the skin. Liposomes are also used in the formulation of drug products where ingredients that are very sensitive or unstable can be “packaged” into capsules to provide the intended therapeutic benefits.