UV Filters Selection

UV Filters in Sun Care Market

Sun care, and in particular sun protection, is one of the fastest-growing segments of the personal care market. Also, UV protection is now being incorporated into many daily-use cosmetic products (for example, facial skin care products and decorative cosmetics), as consumers become more aware that the need to protect themselves from the sun does not only apply to a beach holiday.

Today’s sun care formulator must achieve high SPF and challenging UVA protection standards, while also making products elegant enough to encourage consumer compliance, and cost-effective enough to be affordable in difficult economic times.

Efficacy and elegance are in fact dependent on one another; maximizing the efficacy of the actives used enables high SPF products to be created with minimal levels of UV filters. This allows the formulator greater freedom to optimize skin feel. Conversely, good product aesthetics encourage consumers to apply more products and therefore get closer to the labelled SPF.

Performance Attributes to Consider when Selecting UV Filters for Cosmetics

Safety for intended end-user group – All UV filters have been extensively tested to ensure that they are inherently safe for topical application; however certain sensitive individuals may have allergic reactions to particular types of UV filters.

SPF efficacy – This is dependent on wavelength of the absorbance maximum, the magnitude of the absorbance, and the breadth of the absorbance spectrum.

Broad spectrum / UVA protection efficacy – Modern sunscreen formulations are required to meet certain UVA protection standards, but what is often not well understood is that UVA protection also makes a contribution to the SPF.

Influence on skin feeling – Different UV filters have different effects on skin feeling; for example some liquid UV filters can feel “sticky” or “heavy” on the skin, while water-soluble filters contribute a drier skin feel.

Appearance on skin – Inorganic filters and organic particulates can cause whitening on skin when used at high concentrations; this is usually undesirable, but in some applications (eg. baby sun care) it can be perceived as an advantage.

Photostability – Several organic UV filters decay on exposure to UV, thus reducing their efficacy; but other filters can help to stabilize these “photo-labile” filters and reduce or prevent the decay.

Water resistance – Inclusion of water-based UV filters alongside oil-based ones often provides a significant boost to SPF, but can make it more difficult to achieve water-resistance.

UV Filter Chemistries

Sunscreen actives are generally classified as organic sunscreens or inorganic sunscreens.

Organic sunscreens absorb strongly at specific wavelengths and are transparent to visible light.
Inorganic sunscreens work by reflecting or scattering UV radiation.

Organic Sunscreens or Chemical Sunscreens

Organic sunscreens are also known as chemical sunscreens. These consist of organic (carbon-based) molecules which work as sunscreens by absorbing UV radiation and converting it to heat energy.

Chemical Types of Organic UV Filters
PABA (para-amino benzoic acid) derivatives Example: Ethylhexyl Dimethyl PABA UVB filters Rarely used nowadays due to safety concerns	Salicylates Examples: Ethylhexyl Salicylate, Homosalate UVB filters Low cost Low efficacy compared to most other filters
Cinnamates Examples: Ethylhexyl Methoxycinnamate, Iso-amyl Methoxycinnamate, Octocrylene Highly effective UVB filters Octocrylene is photostable and helps to photo-stabilize other UV filters, but other cinnamates tend to have poor photostability	Benzophenones Examples: Benzophenone-3, Benzophenone-4 Provide both UVB and UVA absorption Relatively low efficacy but help to boost SPF in combination with other filters Benzophenone-3 is rarely used in Europe nowadays due to safety concerns
Triazine and triazole derivatives Examples: Ethylhexyl triazone, bis-Ethylhexyloxyphenol Methoxyphenyl Triazine Highly effective Some are UVB filters, others give broad spectrum UVA/UVB protection Very good photostability Expensive	Dibenzoyl derivatives Examples: Butyl Methoxydibenzoylmethane (BMDM), Diethylamino Hydroxybenzoyl Hexyl Benzoate (DHHB) Highly effective UVA absorbers BMDM has poor photostability, but DHHB is much more photostable
Benzimidazole sulfonic acid derivatives Examples: Phenylbenzimidazole Sulfonic Acid (PBSA), Disodium Phenyl Dibenzimidazole Tetrasulfonate (DPDT) Water-soluble (when neutralized with a suitable base) PBSA is UVB filter; DPDT is a UVA filter Often show synergies with oil-soluble filters when used in combination	Camphor derivatives Example: 4-Methylbenzylidene Camphor UVB filter Rarely used nowadays due to safety concerns
Anthranilates Example: Menthyl anthranilate UVA filters Relatively low efficacy Not approved in Europe	Polysilicone-15 Silicone polymer with chromophores in the side chains UVB filter

Key Applications: Organic filters can in principle be used in all sun care / UV protection products but may not be ideal in products for babies or sensitive skin due to the possibility of allergic reactions in sensitive individuals. They are also not suitable for products making “natural” or “organic” claims as they are all synthetic chemicals.

Organic Sunscreens – What are the Main Strengths & Weaknesses?

Strengths	Weaknesses
Cosmetic elegance – most organic filters, being either liquids or soluble solids, leave no visible residue on the skin surface after application from a formulation	Narrow spectrum – many only protect over a narrow wavelength range
Traditional organics are well understood by formulators	“Cocktails” required for high SPF
Good efficacy at low concentrations	Some solid types can be difficult to dissolve and maintain in solution
	Questions over safety, irritancy and environmental impact
	Some organic filters are photo-unstable

Inorganic Sunscreens or Physical Sunscreens

These sunscreens are also known as physical sunscreens. These consist of inorganic particles which work as sunscreens by absorbing and scattering UV radiation. Inorganic sunscreens are available either as dry powders or pre-dispersions.

Chemical Types of Inorganic UV Filters
Titanium Dioxide Primarily a UVB filter, but some grades also provide good UVA protection Various grades available with different particle sizes, coatings etc. Most grades fall into the realm of nanoparticles Smallest particle sizes are very transparent on skin but give little UVA protection; larger sizes give more UVA protection but are more whitening on skin	Zinc Oxide Primarily a UVA filter; lower SPF efficacy than TiO₂, but gives better protection than TiO₂ in the long wavelength “UVA-I” region Various grades available with different particle sizes, coatings etc. Most grades fall into the realm of nanoparticles

Key Applications: Inorganic sunscreens are suitable for any UV protection applications except clear formulations or aerosol sprays. They are particularly well suited for baby sun care, sensitive skin products, products making “natural” claims, and decorative cosmetics.

Inorganic Sunscreens – What are the Main Strengths & Weaknesses?

Strengths	Weaknesses
Safe / non-irritant	Perception of poor aesthetics (skin feel and whitening on skin)
Broad spectrum	Powders can be difficult to formulate with
High SPF (30+) can be achieved with a single active (TiO₂)	Inorganics have been caught up in the nano debate
Dispersions are easy to incorporate
Photostable

View all inorganic UV filters used in cosmetics »

Performance / Chemistry Matrix

	Cost	SPF	UVA Protection	Skin Feel	Whitening	Photo-stability	Water Resistance
Benzophenone-3	-2	+4	+2	0	0	+3	0
Benzophenone-4	-2	+2	+2	0	0	+3	0
Bis-ethylhexyloxyphenol Methoxyphenyl Triazine	-4	+5	+5	0	0	+4	0
Butyl Methoxy-dibenzoylmethane	-2	+2	+5	0	0	-5	0
Diethylamino Hydroxy Benzoyl Hexyl Benzoate	-4	+1	+5	0	0	+4	0
Diethylhexyl Butamido Triazone	-4	+4	0	0	0	+4	0
Disodium Phenyl Dibenzimiazole Tetrasulfonate	-4	+3	+5	0	0	+3	-2
Ethylhexyl Dimethyl PABA	-1	+4	0	0	0	+2	0
Ethylhexyl Methoxycinnamate	-2	+4	+1	-1	0	-3	+1
Ethylhexyl Salicylate	-1	+1	0	0	0	+2	0
Ethylhexyl Triazone	-3	+4	0	0	0	+4	0
Homosalate	-1	+1	0	0	0	+2	0
Isoamyl p-Methoxycinnamate	-3	+4	+1	-1	0	-2	+1
Menthyl Anthranilate	-3	+1	+2	0	0	-1	0
4-Methylbenzylidene Camphor	-3	+3	0	0	0	-1	0
Methylene Bis-Benzotriazolyl Tetramethylbutylphenol	-5	+4	+5	-1	-2	+4	-1
Octocrylene	-3	+3	+1	-2	0	+5	0
Phenylbenzimidazole Sulfonic Acid	-2	+4	0	0	0	+3	-2
Polysilicone-15	-4	+1	0	+1	0	+3	+2
Tris-biphenyl Triazine	-5	+5	+3	-1	-2	+3	-1
Titanium Dioxide – transparent grade	-3	+5	+2	-1	0	+4	0
Titanium Dioxide – broad spectrum grade	-3	+5	+4	-2	-3	+4	0
Zinc Oxide	-3	+2	+4	-2	-1	+4	0
Rate from -5 to +5: −5: significant negative effect \| 0: no effect \| +5: significant positive effect Note: for cost and whitening, “negative effect” means cost or whitening is increased

Factors Impacting Performance of UV Filters

Performance attributes of titanium dioxide and zinc oxide vary considerably depending on the individual properties of the specific grade used, eg. coating, physical form (powder, oil-based dispersion, water-based dispersion). Users should consult with suppliers before selecting the most appropriate grade to meet their performance objectives in their formulation system.

The efficacy of oil-soluble organic UV filters is influenced by their solubility in the emollients used in the formulation. Generally, polar emollients are the best solvents for organic filters.

The performance of all UV filters is critically influenced by the rheological behavior of the formulation and its ability to form an even, coherent film on the skin. The use of suitable film-formers and rheological additives often helps to improve the efficacy of the filters.

Interesting Combination of UV filters (synergies)

There are many combinations of UV filters that show synergies. The best synergistic effects are usually achieved by combining filters that complement each other in some way, for example:-

Combining oil-soluble (or oil-dispersed) filters with water-soluble (or water-dispersed) filters
Combining UVA filters with UVB filters
Combining inorganic filters with organic filters

There are also certain combinations that can yield other benefits, for example it is well known that octocrylene helps to photo-stabilize certain photo-labile filters such as butyl methoxydibenzoylmethane.

However, one must always be mindful of intellectual property in this area. There are many patents covering particular combinations of UV filters and formulators are advised to always check that the combination they intend to use does not infringe any third-party patents.

UV filter Selection for Cosmetics

The following steps will help you select the right UV filter(s) for your cosmetic formulation:

Set out clear objectives for the performance, aesthetic properties and intended claims for the formulation.
Check which filters are permitted for the intended market.
If you have a specific formulation chassis that you wish to use, consider which filters will fit with that chassis. However if possible it is best to choose the filters first and design the formulation around them. This is especially true with inorganic or particulate organic filters.
Use advice from suppliers and/or prediction tools such as the BASF Sunscreen Simulator to identify combinations that should achieve the intended SPF and UVA targets.

These combinations can then be tried in formulations. In-vitro SPF and UVA testing methods are useful at this stage to indicate which combinations give the best results in terms of performance. The test results, along with the results of other tests and assessments (eg. stability, preservative efficacy, skin feel), enable the formulator to select the best option(s) and also guide the further development of the formulation(s).

Related Read: Alternative In-Vitro SPF Sunscreen Test Method »

UVA/SPF: Upgrade your Test Strategy for Regulatory Compliance

Talk to Julian Hewitt where he will help you avoid running expensive tests and show you how to support formulation work & UVA/SPF claims for your targeted markets (EU, US, Japan). He will also help you learn about conducting right test at the right time (in-vitro or in-vivo) & how to interpret test results better.

Available UV Filters for Cosmetics & Personal Care Products

View a wide range of UV filters / sunscreen agents available today, analyze technical data of each product, get technical assistance or request samples.

What's Next?

Learn strategies to formulate natural sun care cosmetics. Talk to Julian Hewitt where he discusses the key parameters of ‘natural’ products and help you optimize in practice your formulations to get appealing natural sun care products with real life cases.

Suppliers

Brands

Selecting UV Filters for Sun Care Products