Anti-pollution claims (1/2): Which clinical tests?

Anne Charpentier (Photo: Central Plaza, Hong Kong - by Jason Wong, via Unsplash)

10 January 2023

Anti-pollution claims (1/2): Which clinical tests?

One of the effects of air pollution on skin — combined with ozone, UV-rays and the Blue Light — is the generation of free radicals and consecutive inflammatory reactions in the long-run. The oxidative stress generally causes a decrease of the natural antioxidant protection and finally reduce the performance of the skin barrier leading to skin damages such as aging, spots and sensitivity, due to multiple disorders in the Stratum Corneum, Epidermis and Dermis (DNA damages, protein carbonylation, enzymatic alteration, inflammation mediators, oxidative, etc.).

The oxidation phenomena can be considered in two stages:

– 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

Associated claims & clinical testing methods

Personal care products or ingredients claiming anti-pollution effects have three main goals:

– Skin detox with a curative action : Cleansing, Detoxifying, Exfoliating, Purifying, Oxygenizing.

– Rebalance the skin with a curative action : Soothing, Moisturizing, Nourishing, pH-regulator, Sebo-regulator, Complexion, Microcirculation, Anti-aging, anti-sagging.

– 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.

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

– The standardized polluted environment. Different testing laboratories (CIDP, proderm, Eurofins…) have developed special polluted boxes to recreate the pollution conditions for in-vitro, ex-vivo or in-vivo testing. Each of them uses specific pollutants (UV, 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 on human testing, as it seems more difficult to submit cells and models to day life normal pollution.

The “anti-pollution” performances of personal care can be studied in three ways, depending on the test : preventive or curative efficacy, short or long-term action, real life condition or controlled pollution conditions.

For a specific “Anti-pollution” claims we have identified the following methods. Before any chemical analysis, specific sample of the skin can be implemented using stripping (caution to the potential adhesive interaction), swabs or glass sticks as removal tool:

– Protection performance: Heavy metal analysis (Lead, Iron Chromium) Syntivia, Zurko research, CIDP... or particles visualization mimicking PM deposit by Eurofins, CIDP, Intertek, BIO-EC, Proderm, …

– Antioxidant : Lipidic peroxidation (SQ-OOH, MDA, vitamin E) by Proderm, Eurofins… or Transcriptomic and proteomic by Phylogene, Oxiproteomics, or Molecular content : SquameScan, FibroTX (Eotech), Raman spectroscopy.

– Detoxifying : Oxygenation Measure of transcutaneous partial pressure of O2 by Eurofins and PHD Trials.

– Skin complexion and radiance : CorlorFace and SkinCam (Newtone technologies), Goniolux (Orion), Skin GlossyMeter (C+K), SkinGlossMeter (Delfin), Samba & Salsa (Bossa Nova Vision), Antera 3D (Miravex),

– Inflammation : Colour measurement by spectrophotometry, dosage of the biomarhkers (IL-1 dosage), Transcriptomic (Phylogene, Oxiproteomics) …

– Skin Structure, visualization, and quantification : LC-OCT, Multiphotonic, confocal microscopy, Raman spectroscopy…