Multifaceted insights: COSSMA

Alexander Kielbassa and Dr Valérie Bicard-Benhamou from Merck present the latest findings in HEV, blue light and IR exposure, explain how to overcome challenges involved in formulating sun care products and point out the options available for creating sustainable products.

Interview with:

Alexander Kielbassa,
Scientific Associate Director

Dr Valérie Bicard-Benhamou,
Scientific Associate Director,
Merck KGaA,
Darmstadt, Germany

COSSMA: What are the most important trends in the use of sun filters?

Alexander Kielbassa (AK), Scientific Associate Director, Merck: In addition to the trend of ever-increasing UV protection levels, pleasant and fast application, attractive formulation formats, and good skin compatibility of the selected UV filter combination all play an important role.

Mineral-based UV filters such as our company’s Eusolex T and UV-Titan products have a great advantage here and are increasingly used. In addition, compatibility of ingredients with environmental aspects is becoming more important.

What have been the latest findings in High Energy Visible light (HEV), blue light and Infrared (IR) light exposure?

Dr Valérie Bicard-Benhamou (VB), Scientific Associate Director, Merck: Protection of the skin against HEV light and IR light are other strongly emerging trends for cutting-edge sun care products.

Scientists showed how the skin encounters stress on a daily basis when exposed to different wavelength bands in the solar spectrum including not only UV light but also visible light and especially the HEV range, as well as the longer wavelengths in infrared; scientists have also made clear that dam-’age within the different skin layers may also stem from these stressors.

The main source of HEV and IR light is natural sunlight itself; indeed, visible and infrared light represent about 90% of the solar spectrum. Therefore, the biological impact of visible (and de facto the HEV range) and IR may be strong.

Another source of blue light is electronic devices: computers, mobile phones, tablets.

How important is protection from HEV, blue and IR light according to you?

VB: Appropriate and controlled doses of HEV and IR may be beneficial for solving different skin issues, however a protection in the HEV and IR ranges is definitely needed.

Although the general public believes that photoprotection is mainly a matter of UV protection, all solar radiations lead to the formation of radical oxygen species (ROS) and the excess of free radicals in skin contributes to premature skin ageing as well as wrinkling.

Visible light and especially high energy visible light trigger pro-inflammatory cytokines, different matrix metalloproteinases expression, or oxidation of proteins and these markers all play a role in accelerating skin ageing, as denoted by sagging skin, inflammation, wrinkles as well as skin tone issues due to hyperpigmentation effects.

IR radiation has the lowest energy but its contribution to the solar spectrum reaching human skin is about 45% and there may be an impact on the integrity of the extracellular matrix.

What are the latest ingredient findings in this field?

VB: We have investigated in two ex-vivo models and at two different wavelength ranges (IR-A and HEV), different products from different origins and light protection strategies: we tested ingredients which play a role in the first defence line as they prevent radiation from entering the skin, for example Eusolex T-AVO. In the second defence line which causes a responsive action in case some radiation should nonetheless enter the skin, we tested three ingredients, two of them were antioxidants, the natural Emblica extract and the synthetic RonaCare AP. The third ingredient was the natural cell protector RonaCare Ectoin. And finally, we also tested the selftanner Dihydroxyacetone.

The five ingredients tested all provided strong performance and protection of human skin explants after IR-A/HEVL irradiation, thus providing a broad protection band in the solar spectrum. This protection was shown on multi-biochemical parameter levels: in the case of the blue light ex vivo study, MMP1, oxidised proteins, opsin-3 and 8-OHdG were positively impacted after the application of our actives on the human explants. In the case of the IR-A study, tropoelastin and MMP-1 were positively impacted by the application of the different ingredients on irradiated human explants.

These findings show that the onset of ageing may be delayed and photoageing damages may be slowed down.

As there is a broad choice of efficient ingredients that can circumvent harmful effects of HEV and IR-A light, consumer needs and preferences can fully be taken into consideration.

What are the challenges when formulating sun care products?

AK: The first challenge is to find effective UV filter combinations for a well-balanced UVA and UVB protection, which act synergistically in order to keep formulation costs low and to reach the intended SPF/UVA level.

Another challenge is to avoid the infringement of innumerable third-party IP of UV filter and ingredient combinations.

And last but not least, achieving a stable and photostable formulation, fully solubilised or dispersed solid actives and UV filters. The formulator has to avoid incompatibilities of ingredients and this for the entire storage period. So, indeed, the number of challenges involved is high.

Excess of free radicals in skin contributes to premature skin ageing and wrinkling. Photo: Designua/Shutterstock.com

How can these challenges be overcome?

AK: Formulating sun care products is something for specialised companies and of course for experienced formulators. It definitely does not fit the recent cosmetic trend of “Do it yourself cosmetics”. Reports and blogs about “DIY sunscreens” have been published on the web, but this is not recommendable at all.

At least in Europe there are enough permitted inorganic, organic and encapsulated UV filters, UV filter combinations available, so that some of the formulation challenges can be overcome. Photostabilisers, SPF boosters and skin-feel enhancers help to create pleasant formulations. Very favourable are Titanium Dioxide UV filter grades of the Eusolex T and UV-Titan range. They are transparent on the skin and are very strong SPF and UVA boosters when combined with organic UV filters. Thus, they keep the total UV filter concentration on a low level. Another beneficial ingredient is the antioxidant Oxynex ST Liquid for sensitive active ingredients. It acts as a photostabiliser for UV filters and improves the long-term UV protection level while acting as a solvent for the UV filters. At the same time, this multi-purpose ingredient even works as an anti-pollution active ingredient for cross-over sunscreens with skin care claims.

How do sun care and sustainability go together?

AK: Please allow me to start with, sun care and properly using sun care is already sustainable – sustainable, as it sustains human skin health, if the skin is not excessively exposed to sun irradiation. With respect to the sustainability of ingredients: There are various sun care products, brands and eco labels available in the field of natural sun care. As they systematically exclude synthetic substances, only inorganic UV filters can be used for achieving and claiming SPF and UVA; e.g. eco-certified Eusolex T-S, Eusolex T-AVO and RonaCare Zinc Oxide. Apart from this, there is a wide range of cosmetic ingredients and cosmetic actives which follows natural sourcing or is even organically grown with clean and “soft” manufacturing steps, without critical impurities and which are biodegradable or of mineral origin.

Could you please provide us with some examples?

VB: The mineral-based UV filters we already mentioned. Sustainability is also an issue in the field of micro plastics, micro plastic beads in particular. A sustainable alternative to plastic beads are the fully inorganic RonaFlair functional fillers. Another option for formulating sustainable or clean beauty sun care is the bio-produced cell protection factor RonaCare Ectoin with its eco-certification. It acts against UVA-triggered premature skin ageing. Other options include the skin-firming RonaCare Poppy Seed Extract, the natural-based Oxynex and Emblica as antioxidants, the algae extract RonaCare RenouMer for anti-ageing and moisturising properties, and finally the natural anti-inflammatory active RonaCare Bisabolol nat.

As sun care includes self-tanning, also our company’s Dihydroxyacetone is COSMOS-registered and NATRUE-compliant.

What biodegradable solutions are there for sun care?

AK: Many ingredients typically used for sun care are readily biodegradable. Alternatives include emollients, emulsifiers, polymers, waxes, stabilisers and many cosmetic actives of natural origin. Of course, there are substances and cosmetic ingredients which are “natural UV absorbers” and readily biodegradable but they have no approval to be used as UV filters in sun care formulas or to claim SPF or UVA levels. UV filters used for human application for cosmetics in EU or OTC in the USA need to be approved after extensive approval processes and only a relatively manageable number of ingredients has this approval.

The list of permitted UV filters includes biodegradable or readily biodegradable substances such as Ethylhe-xyl Salicylate, Ethylhexyl Methoxycinnamate or Benzophenone-3, but these substances are controversially discussed for other reasons. Biodegradability does not apply to ingredients and UV filters of mineral origin.

Visible and infrared radiations represent about 90% of the solar spectrum. Photo: Magnetix/Shutterstock.com

What options are there for UV protection in compliance with reef safety?

AK: This is an important but very controversially discussed topic currently, because there is no full and scientifically sound comparison between the different UV filters. So far, there are no methods available to specifically assess effects on coral reefs. At this moment, the only possible comparison is based on available data such as aquatic toxicity and biodegradation. A real grading of UV filters is nevertheless difficult as they have a low aquatic toxicity but poor biodegradability or a good biodegradability but higher aquatic toxicity. None of the permitted UV filters has a truly positive profile for both aquatic toxicity and biodegradation.

Since good UV protection means protection against UVA and UVB light, there is a need to rely on a complex combination of UV filters. Limiting the number of permitted UV filters further restricts manufacturers and choices critically.

Much more future research is needed to specifically assess toxicity on coral reefs. Numerous parameters need to be considered in order to develop a validated method and to be able to understand if and how UV filters differ in their effects. Amongst others, analytical measurements need to be carefully considered in order to be able to link effects observed in laboratory test systems to concentration measurements in the ocean and investigations of coral reefs as ecosystems.

A recent publication on Octocrylene by Pawlowski et al. discusses that, due to the poor water solubility and high surface adsorption properties of some UV filters, concentrations measured in the ocean or sea can be severely flawed.

It will still take considerable time before validated methods are available for assessing complex ecosystems such as that of coral reefs. We face a lengthy period where comparing results from various experiments leads to high speculation as to which UV filters are least toxic to coral reefs.

Last but not least, UV filter exposure might be only a minor aspect that needs to be evaluated to understand coral bleaching, the results from polyps expelling algae.

It is generally accepted that increased sea-water temperature due to global warming is the main cause for this phenomenon as shown by Baird et al. Moreover, apart from UV filters, several other major factors might trigger coral bleaching: excessive UV radiation, ocean acidification, rising sea level, physical destruction, mass tourism in general, bacterial/viral pathogens as well as environmental pollutants.

Based on in situ and laboratory experiments, some researchers such as Danovaro postulated an effect of certain UV filters as one of the reasons for disturbing the symbiosis of polyps and algae. The relevance of these effects observed in the laboratory for the overall process of coral bleaching is not known. Moreover, only a few UV filters e.g. Benzophenone-3 have shown effects. In a study by Mitchelmore, concentrations of organic UV filters, hormones and surfactant degradation products were analysed around Hawaii, among others in coral tissue, but without linking this directly to toxic effects.

In the field of inorganic UV filters, a study of Corinaldesi and Italian universities showed that Eusolex T-2000 does not affect corals.

In conclusion, although it would be beneficial to develop reef-friendly UV filters or sunscreen formulations, current knowledge is too limited for a serious attempt to do so. Instead, claiming to be reef-friendly by avoiding the use of the two UV filters banned in Hawaii, Benzophenone-3 and Ethylhexyl Methoxycinnamate, and substituting them by other mineral-based or organic UV filters not touched by this ban, is unfortunately a current trend.

Much more research is needed to substantiate such a claim in the future or even to determine if any newly developed UV filter substances are indeed more reef-friendly while at least equally safe for humans. With animal testing bans in place, developing new UV filter substances and having these approved by authorities without conducting animal tests is nearly impossible.

Our company currently closely follows the developments in evaluating products’ toxicity to coral reefs and will keep the product portfolio as is until more robust scientific data becomes available, justifying another decision.

What are the latest developments in the US concerning the use of UV filters?

AK: Coral friendliness is particularly gaining in importance in the US due to the announced Hawaii ban of Octinoxate and Oxybenzone starting in 2021.

The US-FDA’s proposed new sunscreen monograph requires additional dermal safety data and use studies for eight permitted organ-ic UV filters in the US, in order to support the “GRASE” status (= generally recognised as safe and effective). To date, the FDA has only confirmed the GRASE status in the USA to the two mineral-based sunscreens Zinc Oxide and Titanium Dioxide. This is why formula-tors are increasingly using these sunscreens.

In addition, in the US the requirements con-cerning UVA will also increase in future.

What do you think of free-from claims in sun care products?

AK: Difficult. Free-from claims are discredit-ing approved raw materials and their applica-tion purpose. After extensive tests and safety studies, especially for Annex substances such as preservatives, UV filters, colorants, these raw materials have been evaluated and ap-proved by professionals and safety experts.

Why are scientific facts, cosmetic specialists and official authorities distrusted in this con-text? There are no permitted alternatives to UV filters and preservatives. Much less is known about so-called alternatives which have been investigated far less than the re-search required for Annex-approval. Why should they be safer?

We are now lucky to have the EU Com-mission’s Technical Document on Cos-metic Claims, the EU’s recommendation how to use free-from claims responsibly.

What formulation techniques help to provide pleasant formulations?

AK: Here, too, there are various approaches. Reducing UV filter concentration to just the necessary level is the first measure. From a skin-feel perspective, UV filters are never cosmetically elegant, and formulating with a pleasant skin feel becomes more difficult the higher the concentration, especially when formulating high and very high SPFs.

Secondly, using SPF synergists and SPF boosters such as physical UV filters. Pleasant formulations can also be achieved with encap-sulated organic UV filters. One example is Eusolex UV-Pearls which have been exten-sively tested for their stability, excellent skin compatibility and smooth, non-greasy skin feel for the consumer.

Another approach is to use a properly selected emollient mix, emulsifiers and skin feel en-hancers, such as the functional filler Ro-naFlair LDP White. It acts as an inorgan-ic/mineral-based micro bead for a light, smooth skin-feel. It also delivers a light diffu-sion effect and has a positive impact on SPF due to its light scattering effects.

How can you avoid recrystallisation of crystalline UV filters?

AK: That is another practical formulation challenge especially in the field of high and very high SPF products. Emollients and sol-vents such as Eusolex OCR and Oxynex ST Liquid help avoid recrystallisation. Maximum solubility tables should be taken into consid-eration as well as recommended pH values for water-soluble UV filters.

The physical-chemical interactions of the UV filter platform with the components of the overall formulation, a substitution of ingredients or small changes in con-centration can totally neutralise a formu-lation. What can be done to avoid these effects?

AK: This is in fact a challenge and avoiding this in advance with a theoretical approach is virtually impossible. There are a multitude of potential interactions of the ingredients, in-cluding the packaging materials. The complex-ity of today’s formulations, especially in view of the demands and claims to be fulfilled, is enormous. The only way to create long-term stable formulations is proper and professional formulation development, careful selection of raw materials, experience and extensive stabil-ity testing. Of course, in line with the trend of “simplified cosmetics”, it is true that the sim-pler a formulation is the less interactions are possible. To a certain degree it can be evaluat-ed in advance to what extent substances and formulations are flexible.