The Behind the Knee (BTK) as an Innovative Test Model for Mechanical and Chemical Irritation, Lotion and Dye Transfer and Testing on Compromised Skin

Aims: The aim of this manuscript is to present innovative applications of the BTK model that can potentially contribute additional aspects of safety evaluations for a broader range of products and materials intended for prolonged skin contact.
Study Design and Methodology: The basic BTK protocol is one 6-h exposure per day for 4 days. Modification to the basic protocol were made for individual studies, as needed.
Results: Studies using fabrics, tissues and films indicate the BTK may be well suited to evaluating these materials for skin compatibility. The BTK test discriminated between; different fabrics, drying methods of the same fabric, similar toilet tissue products, and two similar topsheet films used as coverings on the surface of a range of absorbent consumer products. The method was used successfully to measure the transfer of lotion, and lotion skin benefits from lotioned absorbent products.
Conclusion: Studies demonstrate that the utility of the BTK goes beyond the original intent of evaluating the potential skin effects of feminine protection products. The ability to compare fabrics, tissues and films indicate the test model may be useful in the development broad range of absorbent consumer products and in textile development. The utility of the model in measuring the transfer of lotion and other materials from products to the skin surface has the potential to fill an important gap in the development of quantitative exposure assessments. Added endpoint measures, such as enhanced visual scoring and sensory effects further increase the ability to differentiate between very similar products without requiring other protocol modifications.