Ethnic variation in the skin irritation response

There is a widespread, but largely unsubstantiated, view that certain skin types may be more susceptible to the effect of skin irritants than others. One expression of this would be that certain ethnic groups may also be more likely to experience skin irritation. As a consequence, when evaluating the skin compatibility of substances/preparations, these differences may need to be taken into account. However, other evidence indicates that, within any particular group, inter-individual variation is likely to be much larger than the differences between means for distinct groups. In this study, we have investigated 2 carefully matched panels of Caucasian and Japanese women volunteers to determine their topical irritant reaction, both acute and cumulative, to a range of materials. The results indicated that the acute irritant response tended to be greater in the Japanese panel and this reached statistical significance with the stronger irritants. Cumulative irritation was investigated only with the weaker irritants and, although again the trend was to a higher response in Japanese compared to Caucasian panelists, this rarely reached significance. Nevertheless, where risk assessment for skin irritation was critical, then at the population level, these differences might be relevant, both for safety in use of substances and products and for skin acceptability.