The skin irritation test is a test used to evaluate the potential of a product causing skin irritation when used by the consumer. Some cosmetics can cause skin irritation by passing through the outer layer of the skin (called the stratum corneum) and enter the layers beneath causing toxic effects to these cells. This in turn causes an immediate immune response, which is typically characterized by redness, itching or pain in the area of contact with the product.
Skin irritation safety testing and risk assessment for new products, and the ingredients they contain, are critical requirements before marketing. In the past, much of these skin testing required the use of experimental animals. However, new best methods for skin irritation and skin corrosion testing and risk assessment are currently being defined, avoiding the need for animal testing methods. Several in vitro test methods have been approved after successful validation and are gaining acceptance by regulatory authorities.
The 3D model available at Creative Bioarray allows the application of the test material directly to the "skin" surface and permits the assessment of dermal toxicity via a wide variety of parameters. It is based on the reconstructed human epidermis (RHE), which closely mimics the biochemical and physiological properties of the upper part of the human skin, namely the epidermis. Tissue viability is determined using the vital dye MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). The reduction of the viability of tissues exposed to chemicals when compared to negative controls is used to predict the skin irritation potential. Additional endpoints can also be derived, including pro-inflammatory mediators, such as IL-1, IL-18, TNF-α, etc. This model allows test materials topical application, so solids, undiluted final formulations, and insoluble test materials can also be tested.