Skin sensitivity study

The purpose of skin sensitivity testing skin's reactivity to a given substance and to detect any potential allergens or irritants . This test is essential to ensure the safe use of cosmetic products, dermatological products, medical devices, and natural ingredients before they are placed on the market.

Performed according to ISO 10993-10 , the test measures a compound's ability to elicit a sensitization-type immune response , generally delayed, after skin contact. It contributes to the biological characterization of materials and the validation of their safety.

Skin sensitivity studies are part of the overall toxicological assessment strategy required by European regulations (Regulation (EC) No 1223/2009 for cosmetics, ISO 10993 for medical devices).

Analytical methods and protocols used

Depending on the type of product and the purpose of the study, several approaches can be used:

• In vitro tests : performed on human cell cultures (keratinocytes, fibroblasts, reconstructed skin models).
  These tests measure the release of inflammatory markers (IL-8, TNF-α) or cell viability after exposure to the tested substance.
  Common methods:
  Direct Peptide Reactivity Assay (DPRA) : evaluates chemical reactivity with skin peptides.
  KeratinoSens™ : measures the activation of cellular pathways involved in sensitization.
  h-CLAT (Human Cell Line Activation Test): analyzes the immune response of dendritic cells.

• Ex vivo or in vivo tests :
  Patch test : controlled application of the substance to human skin (often on healthy volunteers or validated models).
  Local lymph node assay (LLNA) , performed on animal models according to international regulatory requirements (although gradually being replaced by alternative in vitro methods).

These approaches are selected based on the type of matrix (ingredient, formulation, material) and the applicable regulations .

Products and matrices concerned

Skin sensitivity testing applies to a wide range of products:

• Finished cosmetic products : creams, serums, lotions, deodorants, hair dyes, sunscreens.
• Natural or synthetic ingredients : plant extracts, essential oils, preservatives, surfactants.
• Medical devices : dressings, implants, gloves, coating materials.
• Chemical products and technical formulations : polymers, solvents, inks, additives.

These analyses guarantee that the tested product does not cause redness, irritation, or delayed allergic reaction , even with repeated use.

Industrial and regulatory applications

Skin sensitivity testing is essential for:

• Ensuring regulatory compliance of cosmetic products and medical devices (ISO 10993-10, REACH, CLP).
• Evaluate skin tolerance during the development of new ingredients.
• Establish evidence of safety in safety files (CPSR report for cosmetics).
• Reducing the use of animal testing through the integration of alternative in vitro tests validated by EURL ECVAM.

This study can be combined with other safety and performance analyses, such as:

• The in vitro skin irritation test .
• Phototoxicity assessment for products exposed to light.

Interpretation of the results

The results allow us to determine:

• The level of risk of skin sensitization (low, moderate or high).
• Safe working conditions for the end user.
• Necessary formulation revisions ( elimination of a sensitizing ingredient, adjustment of pH or preservative system).

Test reports include a detailed scientific interpretation in accordance with ISO standards and OECD recommendations.

YesWeLab's expertise

YesWeLab provides a network of partner laboratories accredited to ISO 17025 and COFRAC , specializing in skin toxicology and biocompatibility testing .

Thanks to the YesWeLab digital platform , it is possible to submit your samples, track your trials and access your analytical reports online .

For any specific request, contact our scientific team to define a protocol adapted to your products and regulatory requirements.