Assessment of the utility of the novel Phenion® full thickness human skin model for detecting the skin irritation potential of antimicrobial cleaning products.

The skin is a potential route of exposure to antimicrobial cleaning products (ACP). Skin irritation, reversible damage to the skin, is an endpoint for protecting consumers and operators accidently exposed to these complex mixtures. To assess skin irritation of 24 ACP formulations, a new protocol was developed and adapted from OECD Test Guideline No. 439 with EpiDerm™ (epidermis model) replaced by Phenion® FT (full thickness tissue, including epidermis and dermis) as the test system. A full thickness tissue was utilized to provide a more human in vivo-like model. Formulations were applied to Phenion® FT and cell viability measured by MTT reduction after a 15-min exposure and 42 h post exposure period. A prediction model was applied, and results compared with in vivo rabbit skin irritation data. Concordance between in vivo and in vitro was demonstrated to be suitable (i.e., sensitivity 78%, specificity 83%, and accuracy 79%) using this modified OECD Test Guideline No. 439 method with a 70% cell viability selected as the most reasonable cut off for discriminating non-irritants (EPA Class IV). These results were considered suitable to develop a draft IATA i.e., with any ACP formulation identified as EPA Category IV in this test. The method will be further refined to distinguish irritant categories.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: KEP and TM are employees of The Clorox Company. CSR is a consultant working with The Clorox Company. KEP is a Special Government Employee for the National Institutes of Health (NIH) and the current chair of the Scientific Advisory Committee on Alternative Toxicological Methods (SACATM). WW is an employee of Charles River Laboratories, subcontracted to perform the in-life testing. KS was an employee of PCRM during the development, conduct and reporting of the project and is now an employee of IIVS.
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