Testing Methods to Quantify Anti-pollution & Anti-blue Light Claims

TAGS:  Skin Care      Anti-pollution Agents    

This article was originally published in 2018 and updated in 2021.

Since the spring 2020, the global COVID pandemic has placed the pollution risks of megacities on a secondary concern. Should viruses be considered as a pollutant? Viruses belong to the large family of microbiota such as:

• Micro-organisms
• Bacteria
• Fungi
• Yeast

As a crucial barrier to virus contagion, hand washing has integrated the normal barrier gestures around the world.


A special focus is made on the evaluation of handwashing products by friction quantifying the reduction in the viability of Escherichia coli. As for the antiviral activity of a hygiene product, its objectivation is considered as pharmaceuticals.

Where Face Skin Pollution Comes From?

The wearing of the mask, sometimes many hours daily, becomes a new parameter to be taken into consideration in assessing the tolerance and effectiveness of cosmetic products. The resulting change in the skin ecosystem is significant and can be akin to close pollution due to the:

• Promoted development of bacteria
• Friction of tissue
• Increased CO₂ humidity
• Temperature as well as sebaceous secretion

The era of air pollution and blue screen has started a few decades ago. And the increased use of the screen with remote meeting all days reinforces the blue-light exposition. These elements of a common lifestyle for the Urban population question the formulators, the marketers, and the regulatory managers.

• How to evaluate the performance of skin care?
• What methods are suitable to respect the regulatory environment of personal care and cosmetics in Europe, in the US or Asia?

But, before answering these questions let's know more about the effect & impact of pollutants on skin physiology, and the claims related to anti-pollution in detail...

What are the various effects of the pollutants on the skin physiology?

One of the effects of air pollution combined with ozone, UV-rays and the Blue Light on the skin is the generation of free radicals and the consequences of inflammatory reactions. The oxidative stress generally causes a decrease in the natural antioxidant protection and finally reduces the performance of the skin barrier.

This stress can induce an increase in the formation of glycated products at several layers of the skin. It produces the Advanced Glycation End Products (AGE). This AGE affects the quality of the extra-cellular matrix by destroying the collagen.

The chronic stress induced by external pollutants alters the integrity of the skin barrier and generate various skin disorders such as:

• Sensitivity
• Pigmentation
• Dermatitis…

Impact on the Skin Physiology: A Question of Time

The oxidation phenomena can be considered in 2 terms:

• Short-term: more toxins, barrier function disorders, low skin resistance to UV, changes in the pH, proteins and lipids, DNA oxidation, Inflammation, pore occlusions, low rate of hydration, oxygen, cell turnover, and sebum increase
• Long-term: wrinkles, age spots, acne, dull and sagging, sensitivity

The skin damages induced are: Aging, Dark spots, and Sensitivity including a multi-factorial consequence in the Stratum Corneum, epidermis and dermis layer:

DNA damages Protein carbonylation Enzymatic alteration Inflammation mediators

Oxidative process Lipids metabolism Cell metabolism, and Dermis structure

Associated Claims & Testing Methods

Cosmetics personal care products or ingredients claiming anti-pollution effects have 3 main aims:

1. Skin detox with a curative action: Cleansing, Detoxifying, Exfoliating, Purifying, Oxygenizing
2. Rebalance the skin with a curative action: Soothing, Moisturizing, Nourishing, pH-regulator, Sebo-regulator, Complexion, Microcirculation, Anti-aging, anti-sagging
3. Protect and isolate the skin with a preventive action: Anti-UV/IR/Anti-blue light, Antioxidant, Anti-free radical, Anti-particles, Barrier integrity, Anti-inflammatory, Anti-spot.

For the blue-light effect, the activity will be focused on the protection and isolation of the skin. It will be similar to UV testing methods and protocols. The source of light will be specifically Blue spectrum and several parameters of the skin physiology would be quantified before and after the treatment.

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What are the two major testing options?

Two major testing options exist to implement the conditions of pollution:

• The standardized polluted environment – Different testing Labs (CIDP, Eurofins, Bio-EC…) have developed special polluted boxes to recreate the pollution conditions for in-vitro, ex-vivo or on human testing. Each of them uses specific pollutants (ozone, particles, cigarette smoke…). The control and the measurement of the pollutants during the test is a key element of its reproducibility.
• The in-situ pollution environment in a polluted city is reserved for the testing on human, as it seems more difficult to submit cells and models to day life normal pollution.

What are the ways to study anti-pollution performances of cosmetics and personal care?

Depending on the substrate of the test, the “anti-pollution” performances of cosmetics and personal care can be studied in 3 ways:

• Preventive or curative efficacy
• Short or long-term action, and
• Real-life condition or controlled pollution conditions

Get Inspired: Anti-pollution Claims - How to test and document them?

Main Claims, Classical Methods and Devices

The following claims can be clinically objectivated with the classical methods and devices for a short or long-term performance:

Cleansing Detoxifying Purifying Soothing Seboregulator pH-regulator Moisturizing

Nourishing Anti-UV Anti-age-spot Anti-oxidant Anti-free radical Radiance, and Skin complexion…

For specific “Anti-pollution” claims we have identified the following methods. All the details of the methods and the devices can be easily found in the “clinical” platform of Skinobs. It is free to access for cosmeticians.

Before any chemical analysis, specific samples of the skin are implemented: stripping (caution to the potential adhesive interaction), swabs or glass sticks.

• Protection performance: Heavy metal analysis (Lead, Iron Chromium) Syntivia, Zurko research, CIDP... or particles visualization mimicking PM deposit by Cerco, CIDP, Intertek, BIO-EC, Proderm, …
• Antioxidant: Lipidic peroxidation (SQ-OOH, MDA, vitamin E) by Lipotype, Synelvia, Proderm, Eurofins… or Transcriptomic and proteomic by Phylogene, Oxiproteomics, or Molecular content: SquameScan (Heiland), FibroTX (Eotech), Raman spectroscopy (RiverD).
• Detoxifying: Oxygenation Measure of transcutaneous partial pressure of O₂ by Cerco and Eurofins.
• Skin complexion and radiance: CorlorFace (Newtone technologies), Goniolux (Orion), Skin GlossyMeter (C+K), Skin GlossMeter (Delfin), GP150 (Seelab), Samba & Salsa (Bossa Nova Vision).
• Inflammation: Color measurement by spectrophotometry, dosage of the biomarkers (IL-1 dosage), Transcriptomic (Phylogene, Oxiproteomics)…
• Skin Structure, visualization and quantification: LC-OCT (Damae), Multiphotonic (Jenlab), Antera 3D (Miravex), confocal microscopy (Vivascope-Mavig, Vivosight-Michelson), Dermascan, Dermcup, Raman spectroscopy (RiverD).

In-vitro and Ex-vivo Testing for the Anti-pollution Objectivation

To address the needs for anti-pollution claims substantiation, the major Testing Labs (CROs) also developed specific in-vitro and ex-vivo protocols that objectively evaluate skin exposure to several pollutants. These assays represent an ethical alternative to human testing when induced stresses (pollution, UV...) are harmful. They can demonstrate the effects in:

• Preventing pollutants from adhering to the skin surface
• Removing pollutants from the skin, or
• Reducing their oxidative impact on several mechanisms of the skin

Several types of pollution stress can be applied, either directly in the cell culture media or by spraying the pollutant on the assay support or in a chamber:

Blue-light(400 – 470 nm) UVA, UVB Infra-red Cigarette smoke Ozone

Heavy metals Volatile organic compounds PM 2.5 Particulate matters Inflammation mediators

Beyond the duration of use that everybody would like longer and longer, 3D skin model - bioprint or not- and ex vivo testing present undeniable benefits for the anti-pollution evaluation through:

• The standardized assay conditions.
• The various end points and their combination of assays with multiple action mechanisms (oxidation, aging, UV stress...), ethical alternative to human testing.
• The quantitative and illustrative results (histology, modelling, video).

There are various methods which enable to evaluate anti-pollutant efficacy on cell supports, skin model or skin 3D print using a large number of biomarker analysis:

• Cell proliferation
• Lipid metabolism
• Carbonylated proteins
• Antioxidant defence markers
• DNA damage
• Various proteins (barrier function, pigmentation or mitochondrial)
• Inflammation mediators, or
• Protease activity

The choice of the test models depends mainly on the studied mechanism of action.

The Various Choice of Assays

Several methods of analysis can quantify or visualise the effect of ingredients or formulation on the cellular metabolism such as:

• Proteic and metabolic methods: Elisa, HPLC, CPG, Flow cytometry, Mass Spectrometry, Photometry, Western Blot, Radio-biochemical…,
• Morphology and imaging methods: 3DLive cell Imager, HTRF, Immuno-histo fluorescence, Immuno-fluorescence chemistry and imaging, electron microscopy…,
• Gene expression: Transcriptomic, RT-qPCR, qPCR-array,
• Multi-omics approach: proteomics, metabolomics that provide untargeted studies of a product or ingredient activity, offering a starting review of its performance potential…

What really boosts the use of in-vitro assays for anti-pollution validation?

A Limitless Choice of Biomarkers

The numerous choices of hundred biomarkers can provide an almost infinite variety of assays on the cellular mechanism of the skin or the hair. For example, to study the regenerating effect which can be altered by the pollution, it is possible to select among various biomarkers such as:

Collagen IV, VII, XVII Elastin fibres & structure Corneodesmosin Cytokeratins Fibronectin Integrins

Kallikreins Lipids peroxidized Lumican Perlecan Psoriasin Sirtuin…

The list is not comprehensive, and almost every month there is a new publication highlighting the interest of new biomarkers for the skin or hair study.


The Infinite Variety of Assay Supports

For in-vitro assays there are significant distinctions between tests on human monolayer cells (primary or lines) commonly used for hydrophilic substances and assays on 3D reconstructed skin models, skin explants and 3D skin bioprint that can be used for lipophilic products. Monolayer cell tests have become a routine with a choice of a multitude of primary cells provided from various skin types and ages:

• Keratinocytes
• Fibroblasts
• Melanocytes
• Sebocytes
• Adipocytes and the opportunity of monoculture or coculture supports

Then, the wide selection of reconstructed skin models is fantastic (baby skin, altered skin, aging skin…) with epidermis model or full thickness skin model.

Most of the CRO’s can buy the standard cells or skin models, can offer their own in-house models, or can also develop particular ones with specific characteristics. To give the best predictive results, they offer sophisticated supports for the various anti-pollution claims on the skin or hair.

A few questions remain.

Get Inspired: Anti-pollution Claims - How to test and document them?

How can the anti-pollution testing evolve?

For efficacy objectivation, in-vitro and ex-vivo methods represent often quicker, cheaper and a reliable proof of concept as predictors of efficacy in humans. The combination of the 3 pillars of the assay design among the selection of the biomarkers, the analytical methods and the assay supports making the in-vitro testing a source of constant innovation for the beauty industry.


Is the future protocol a standardized one or not? An "ideal" protocol could give more information about:

• The standardized or modelized conditions of pollution
• The nature of the pollutants
• The ethical considerations

How many Apps or websites are now available to test the pollution environment? And tell the consumers about anti-pollution actions and products?

These new digital methods combine the ultra-personalization trend with the geo-tracking and the A.I. And, they will certainly influence the future of the new anti-pollution cosmetics development.

Anti-pollution Claims: How to Test and Document Them?

Take the course by our industry expert where he will share high insights & ideas about anti-pollution claims (preventions vs repair), test methods & clinical protocols for such claims, and criteria for choosing instruments.

Anti-pollution Actives for Variety of Cosmetics Products