BACKGROUND: Cosmetics are products used over long periods by the public, and their safety is very important. Several types of human tests are used widely for the evaluation of cosmetics includ- ing single patch tests, in-use tests, human repeated insult patch test (HRIPT). However, there is no clear and well-defined published objective and standardized criteria for primary skin irritation in regard to the large variety of cosmetic products.
METHODS: This study analysed human patch tests conducted from May 2001 to December 2012 with 4606 materials of proto- type or finished cosmetic products on 7440 normal Korean women aged 1860 years. The tested products were patched under occlu- sion for 24 or 48 h, and skin tolerance was assessed twice at 30 min and 24 h after patch removal using a 5-step scale accord- ing to the CTFA guidelines.
RESULTS: Human patch tests for cosmetics were performed of 4606 cases, and 3033 subjects participated in each case. The response in each case was calculated based on total subject num- ber, skin reaction intensity and the number of respondents. The calculated response was standardized using the z-score, and a safety zone was provided in terms of human primary irritation in accordance with the human skin reaction evaluation criteria and usage or formula of cosmetics.
CONCLUSIONS: This study established the safety criteria for irritation in the cosmetics field