Dermal Irritation. In Vitro Evaluation of Skin Irritation

Since skin is the main target of cosmetic products, it is essential to evaluate a potential of a particular product or cosmetic ingredient to cause skin irritation. Skin Irritation testing is naturally a part of the overall safety assessment process for cosmetic products.

Decision on possible unwanted dermal effects of cosmetics, such as skin irritation or corrosion, should be based on tiered strategy and a weight of evidence analysis, where all available information are taken into account to provide complete picture about the skin tolerance of an ingredient or product. This include: information from databases (human and animal data), QSARs, pH considerations and results from in vitro tests. Use of animals for the assessment of cosmetics is longer no more an option in the EU.

To date, there are several formally validated and regulatory accepted in vitro methods for assessment of skin corrosion and irritation of cosmetic ingredients. They are mostly based on the use of reconstructed human epidermal (RhE) models such as EpiSkin™, EpiDerm™ and SkinEthic™. These assays underwent formal validation and regulatory acceptance at the EU and OECD levels and are used mostly for hazard assessment i.e. for classification and labeling purposes (OECD TG 431, accepted in 2004 and OECD TG 439, accepted in 2007).

For skin tolerance testing, the RhE models are used already for more than 20 years, however, protocols with long exposure times are used to better mimic the in-use conditions. An international project investigating the capacity of different RhE models to correctly address the irritation potential of cosmetic products was conducted around 2000 and supported by grant from the European Committee DGXII (Standards, Measurements and Testing, SMT4-CT97–2174).  This study clearly demonstrated the usefulness of RhE for the in vitro assessment of the irritation potential of a series of cosmetic products. These models allowed the measurement of quantifiable and objective endpoints relevant to in vivo irritative phenomena (Faller et al, 2002).
The presentation will provide state of the art overview on assessment of the skin irritation potential of cosmetics using RhE models.  

Dr. Helena KandarovaSlovak Republic