Ensure Children’s Cosmetic Product Safety Through In Vitro Tissue Models

Ensuring the safety of products we use every day, especially for children, is more important than ever. When there is limited information to assess the safety profile of ingredients or products, in vitro assays using reconstructed human tissue models are the first recommended approach to evaluate safety and toxicity.

Reconstructed human tissue models, such as reconstructed human epidermis (RHE), are widely used in regulatory testing, providing an ethical and reliable alternative to animal testing. RHE models are designed to closely replicate the structure and function of human skin, specifically the epidermis, the protective barrier of the skin. These models can be used to evaluate whether products cause irritation, toxicity or absorption issues, following the Organization for Economic Cooperation and Development (OECD) 439 guideline. Cell viability, inflammation markers and skin differentiation markers are analyzed to assess the irritation potential of the product on the skin. Various ingredient combinations or concentrations can be compared in parallel, which supports R&D processes and saves both time and resources. Moreover, it provides an ethical alternative to clinical testing for tolerance evaluation during product development.

In addition to epidermis models, human reconstructed epithelium models are also essential for evaluating the tolerance of products intended for specific areas of the body, such as the oral, gingival, ocular or nasal regions. These models are particularly useful for products like baby toiletries, children's toothpaste and pediatric medical devices.

Ocular epithelium models are similarly used in the development of products such as children's shampoos and eye care products. The OECD 492 guideline is typically followed for these models to ensure that products are safe for the ocular area.

Newborn skin has the same number of layers as an adult, but each layer is thinner – about 20-30% thinner than adult skin. It is also more fragile and prone to dehydration. The upper epidermal layers, especially the stratum corneum, are less developed, providing a weaker barrier against water loss and infections. Therefore, the skin of a newborn or young child requires extremely gentle and protective hygiene care.

Tests for these products require specialized models that more accurately mimic immature skin. Immature epidermis models are constructed similarly to standard RHE but feature thinner upper layers to reflect neonatal skin. Roso et al. (2021) demonstrated that immature epidermis models are more sensitive than standard RHE models, allowing for more accurate evaluations of product tolerance in neonatal skin. A multiparametric approach – incorporating cytotoxicity testing, inflammatory markers and histological analysis – ensures a thorough and reliable assessment of products designed for young children to enhance safety.

Companies can use these advanced tissue models to avoid animal testing while still prioritizing safety. This scientific approach provides parents with peace of mind, knowing that the products they use on their children have been tested ethically and thoroughly to meet the highest safety standards.

References:

• OECD Guidelines for the Testing of Chemicals, Section 4 - Test No. 439: In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method, 14 June 2021.
• OECD Guidelines for the Testing of Chemicals, Section 4 - Test No. 492: Reconstructed human Cornea-like Epithelium (RhCE) test method for identifying chemicals not requiring classification and labelling for eye irritation or serious eye damage.
• Roso A, Puginier M, Bergal M, Nunzi F, Alonso A. In vitro Approach to Assess Local Tolerance of Ingredients Dedicated to Specific Topical Care Applications. J. Dermatol & Skin Sci. 2021;3(1):30-48.