Ethnic differences in objective and subjective skin irritation response: an international study.

ABSTRACT

BACKGROUND: Due to global marketing in the cosmetics industry, it is important to assess ethnic population susceptibility when evaluating the safety of cosmetic products or chemicals. OBJECTIVES: To investigate ethnic variations in skin irritation response to positive irritants. METHODS: Clinical testing was performed in four countries on two ethnic groups - Asian and Caucasian. We performed patch tests on the subjects' back with 0.5% aqueous sodium lauryl sulfate (SLS) and 0.15% retinol prepared in 1,3-butylene glycol. Stinging tests were performed using 5% aqueous lactic acid and 0.001% (w/v) capsaicin prepared in 10% ethanol solution separately. RESULTS: The incidence of self-perceived skin sensitivity was similar in the two ethnic groups. However, the incidence of adverse skin reaction to cosmetics appeared significantly higher in Asian (33.0%) than in Caucasian subjects (11.3%). For standard positive irritants such as 0.5% aqueous SLS solution, Asian subjects showed significantly higher scores than Caucasian subjects. The incidence of positive reaction to the 0.15% retinol patch test tended to be higher in Asian than in Caucasian subjects. Our data also showed that neurosensitivity to 5% lactic acid and 0.001% capsaicin was higher in Asian than in Caucasian subjects. CONCLUSION: Although self-reported skin sensitivity does not appear to differ according to ethnicity, there are ethnic differences in objective and subjective skin irritation responses to several standard positive materials.