Abstract

Sensory irritation, such as stinging, pricking or burning sensations, can be occasionally caused by skin cosmetics. Since skin cosmetics are used daily and left on the skin surface for an extended period of time after application, any associated sensory irritation can be unpleasant for consumers. However, the mechanisms of sensory irritation caused by chemical stimuli on the skin surface are still unknown. Recently, it has been demonstrated that Transient Receptor Potential (TRP) channels are described to potentially have important roles in sensing nociceptive stimuli. We determined that parabens and alkali agents cause TRPA1, a nociceptive sensor, activation to establish an alternative evaluation method for sensory irritation from cosmetics.

INTRODUCTION

Most people use cosmetics every day. For instance, each day, people may use lipstick, skin toner, foundation, shampoo, body soap, perfume, shaving foam, etc. Potentially, the use of cosmetics can lead to skin irritation. Skin irritation can be classified roughly into two phenomena: skin inflammation and sensory irritation. Alternative methods for evaluation of skin inflammation are very advanced, as several reports involving 3D skin or cultured cells have been published (1, 2). Although a few reports have been published regarding alternative tests for sensory irritation (3, 4), we were not aware of a useful alternative test for sensory irritation. Knowledge about sensory irritation has accumulated recently and as a result, sensory irritation by cosmetics was found to be rare. However, many consumers seem to have given up using cosmetics or have started using other cosmetics because of sensory irritation. When a consumer experiences stinging or burning from using skin cosmetics, how does he/she feel? If it happens the first time she uses that kind of skin cosmetic, he/she may never use it again. We must see it as a lost chance at making one o ...