Nanomaterial safety and regulations in personal care product development

 

1. Brief history of nanomaterial regulations

 According to Wikipedia, the word “nanotechnology” was first coined by Professor Norio Taniguchi of Tokyo University in 1974. He used it to describe semiconductor processes such as thin film deposition and ion beam milling, which exhibit characteristic control on the order of a nanometer.  Since the 1980s, the term nanotechnology has been referring to the fabrication, use/manipulation, control and characterization of structures devices or materials with a least one dimension in the size range of 1–100 nm. ^1,2

Nanotechnologies represent a fast-growing market, bringing with them a combination of benefits, promises, risks, and uncertainties.  It is synonymous with high technology and high efficacy. It has often been used as a buzzword in advertisements and label claims of many consumer products, including personal care products, to gain attention.  Various physical and chemical properties of a material can be affected by its particle size. Nanomaterials have been engineered to have enhanced properties and performance that are beyond their non-nano counterparts. However, these much enhanced properties also raises questions about their safety.

In June 2007, the safety of nanomaterials such as nano TiO₂ in sunscreen and fulluerene was raised in the article, Nanotechnology, the untold promise, and unknown risk, in Consumer Reports.  In August 2007, Friend of Earth (FOE) published Technology and Sunscreens, raising the particular concern over nano TiO₂ and ZnO in sunscreens and calling for labeling and regulation of nanomaterials in consumer products. Earlier in 2006, a coalition of environmental and consumer groups, including the International Center for Technology Assessment, Friends of the Earth, and Our Bodies, Ourselves, filed a legal petition with the Food and Drug Administration (FDA) asking FDA to regulate nanotechnology.

The first regulatory move was made by European Commission (EC).   EC acknowledged the safety concerns considering that nanomaterials could have very different physical and chemical properties over their non-nano counterparts, potentially resulting in different toxicological profiles. In 2005, the EU Scientific Committee on Consumer Products was requested by EC to provide a scientific opinion on the safety of nanomaterials in cosmetic products, in particular, the appropriateness of existing methodologies to assess the potential risk associated. This created public fear regarding nanomaterials in consumer products, especially in personal care products. In the meantime, the uncertainty of the future regulatory landscape made it extremely difficult for cosmetic formulators to incorporate nanomaterials in any formulation.

In 2009, REGULATION (EC) No 1223/2009 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 30 November 2009 on cosmetic products stated the purpose and need of a definition of nanomaterial, which has been evolving since. Most recently, COMMISSION RECOMMENDATION of 10 June 2022 on the definition of nanomaterial, C 229/1, defines nanomaterial as follows:

Nanomaterial means a natural, incidental, or manufactured material consisting of solid particles that are present, either on their own or as identifiable constituent particles in aggregates or agglomerates, and where 50 % or more of these particles in the number-based size distribution fulfill at least one of the following conditions:

– one or more external dimensions of the particle are in the size range 1 nm to 100 nm;
– the particle has an elongated shape, such as a rod, fibre or tube, where two external dimensions are smaller than 1 nm and the other dimension is larger than 100 nm.
– the particle has a plate-like shape, where one external dimension is smaller than 1 nm and the other dimensions are larger than 100 nm

Moreover, Article 16 of Regulation (EC) No 1223/2009 on cosmetic products requires that, in addition to the notification under Article 13, cosmetic products containing nanomaterials shall be notified to the Commission by the Responsible Person using electronic means six months prior to being placed on the market. Notification should be done on Cosmetic Products Notification Portal (CPNP).

 

2. Interpretation of nanomaterial definition:

The interpretation of the nanomaterial definition depends to a large extent on the size measurement method. Because of the structural complexity of nanomaterials, no single test method is capable of measuring all nanomaterials precisely and properly. EC recommends determining nanomaterial by its primary particle size or internal structure while allowing sectoral interpretation according to the actual use conditions, which may vary drastically from industry to industry.

In 2011, Cosmetic Europe issued their own interpretation of EC definition of nanomaterial, and then an update in 2019, stating that “materials with constitutive elements having a dimension in the nano-range (e.g. aggregates, agglomerates, composites) but that are themselves greater than 100 nm in size should not be considered as nanomaterials unless they release nano-objects or aggregates of less than 100 nm in size in cosmetic products under normal use conditions”.  Accordingly, the size of aggregates or agglomerates is used to determine the nanomaterial for labeling cosmetic products. This interpretation has been followed by many cosmetic companies.

 

3. Commercial use of nanomaterials

According to a EC’s report, Sub-working group of on nanomaterial definition, published on January 28, 2021, 37,647 cosmetic products were notified with nanomaterials in EU market, (via Art.13 procedure), which corresponds to about 1.5% of all notifications. According to 2015 – 2020 data, on average, about 10 new cosmetic products containing nanomaterials are placed on the EU market every day.

Most common product categories with nanomaterials: (64% of all nanomaterials notifications):

1. Sun protection
2. Nail varnish/nail make up
3. Oxidative hair care
4. Foundation
5. Lip care products and lipsticks

The most used cosmetic ingredients are reported below (4 ingredients accounts for over 70% of all CPNP notifications):

1. Titanium Dioxide
2. Silica Dimethyl Silylate, Silane, dichlorodimethyl-, reaction products with silica
3. Carbon Black nano (CI77266)
4. Silica

Scientific Committee for Consumer Safety (SCCS) under European Commission is requested by EC to evaluate the safety of the listed nanomaterials via a process that was based on the scientific literature available at the time and SCCS’ expert judgment. In early 2021, SCCS published an advice on the safety of nanomaterials in cosmetics, in which nanomaterials of concern were separated into two groups. ³

     — 16(4) of the Cosmetics Regulation

28 substances including silica, Titanium dioxide, Zinc oxide, Methylene Bis Benzotriazolyl Tetramethylbutylphenol were listed in the appendix 1 in an order of priority according to risk potential (based on a number of criteria).

     — 16(6) of the Cosmetics Regulation

SCCS reviewed three previous inclusive opinions on colloid silver, nano styrene/acrylate polymer and nano silica, and identified certain aspects relating to each of these nanomateirals that raised safety concern.

 

4. Nano TiO₂ /ZnO in sunscreens

For personal care products, nano TiO₂ and ZnO are perhaps the two most concerning ingredients due to their wide use as sunscreen actives. Because of their very small primary particle size, nano TiO₂ and ZnO are much more transparent on the skin and much more potent in UV protection than their non-nano or pigmentary counterparts. For instance, pigmentary TiO₂ is known to be completely opaque and cannot be used in any skin care product for effective UV protection.  Nano TiO₂, with a primary size of 10 – 20 nm, is not only highly transparent but also provides 5 – 6 times higher SPF.   For this reason, nano TiO₂ and ZnO have been used widely in sunscreen products in Japan and Australia since 1980s.  They have been popular among those having sensitive skin and allergic to organic sunscreens.

Up to now, and after the use by hundreds of millions of consumers, there have been no reports of any adverse health effects for nano TiO₂ and ZnO. However, they were still put under great scrutiny due to the general concerns and fear that were raised for nanomaterials in early 2000s.  Many customers, especially in EU, became somewhat nanophobic at the time as the future of regulatory landscape remained uncertain.

For topical application, the major concern is transdermal adsorption or penetration.  After years of study, SCCS issued in 2012 OPINION ON Zinc oxide (nano form) COLIPA S76 stating that “There is no evidence for the absorption of ZnO nanoparticles through skin and via the oral route. Even if there was any dermal and/or oral absorption of ZnO nanoparticles, continuous dissolution of zinc ions would lead to complete solubilization of the particles in the biological environment.” ⁴ Two years later, the SCCS issued the OPINION ON 22 on Titanium Dioxide (nano form), stating “the main consideration in the current assessment is the apparent lack of penetration of TiO₂ nanoparticles through skin.” ⁵

Another concern is photo-catalytic activity of nano TiO₂ that lead to generation of free radicals and ensuing oxidation.  Surface treatment of nano TiO₂ had been quite common, and the data collected by SCCSs on commercial grades confirmed that the photo-catalytic activity could be much suppressed by surface treatment.

Finally, EU revised the nano TiO₂ monograph for use as UV filters in 2016. The key updates included a list of allowed surface treatments and a limit on the photocatalytic activity. In the same year, ZnO was officially approved as an UV filter, and a list of surface treatments and solubility specification were included in the monograph. ⁶

After years of investigation, EC finally concluded that nano TiO₂ and ZnO were safe for personal care use as long as:

1. They comply with the specifications in the EU monographs.
2. The final product will not lead to exposure of the end-user’s lungs by inhalation.

For other nanomaterials under review, the SCCS has yet to establish final opinions. The future regulatory status remains uncertain.

 

5. Regulations in other regions

Nanomaterial is generally defined as a material with internal or external dimensions in the range of 1 – 100 nm in other regions.   Many regulatory agencies share similar concerns to EC’s, but they have not acted as swiftly as EC.  Although there are guidelines for considering the safety of nanomaterials, there are few laws enacted to regulate them.  To the author’s knowledge, there are two regulations outside EU:

A) Canada – If a sunscreen product contains only inorganic UV filters, nano TiO₂ and/or ZnO, it is considered a Natural Health Product, for which the premarket approval is not needed. However, if any of the two is used with organic UV filters, the sunscreen is a drug product. Safety of nano TiO₂/ZnO needs to be addressed and approved, which can be painstaking. Further, there is no official test method and threshold for classifying nanomaterials.

B) China – “Regulations on the Supervision and Administration of Children’s Cosmetics” issued by the State Food and Drug Administration (2021 No. 123), was issued in 2021. Section 7.1 states that:

“….. New raw materials that are still in the monitoring period should not be used, and raw materials prepared by new technologies such as genetic technology and nanotechnology should not be used. If there is no alternative raw material that must be used, the reason should be explained, and evaluate the safety of children’s cosmetics”.

Since nano TiO₂ and ZnO are not new technologies, they could be exempted from this regulation. However, the ambiguity in interpreting the regulatory language and difficulty in effective communication with Chinese officials have made many company shy away from nano TiO₂ or ZnO, and instead turning to the non-nano grades.

 

6. Summary

Nanomaterial safety and regulations are important to personal care product development. Many nanomateterials used in our industry are under safety review and their future is uncertain. As far as nano TiO₂ and ZnO are concerned, it is official that they are safe as long as they are not exposed to end-users’ lung in application. Due to the complex structures of nanomaterials, their size analysis method, data interpretation and regulatory classification have been constantly investigated and are still evolving. Formulators are highly advised to consult with their regulatory experts as well as the suppliers when choosing nano or non-nanomaterials.

 

References:

1. (2007a) Opinion on: the Scientific Aspects of the Existing Proposed Definition Relating to Products of Nanoscience Nanotechnologies. Brussels: European Commission Health Consumer Protection Directorate General.
   SCENHIR. (2007b) Opinion on: the Appropriateness of the Risk Assessment Methodology in Accordance with the Technical Guidance Documents for the New and Existing Substances for Assessing the Risk of Nanomaterials. Brussels.

2. ISO/TS 27687. (2008). Nanotechnologies – Terminology and Definitions for Nano-objects – Nanoparticle, Nanofibre and Nanoplate.
3. SCCS/1618/2020 Scientific Advice; https://health.ec.europa.eu/system/files/2022-08/sccs_o_239.pdf
4. SCCS/1489/12; https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_103.pdf
5. SCCS/1516/13 Revision of 22 April 2014; https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_136.pdf
6. COMMISSION REGULATION (EU) 2016/1143 of 13 July 2016, amending Annex VI to Regulation (EC) No 1223/2009 of the European Parliament and of the Council on cosmetic products