Confocal Raman microscopy for investigating the penetration of various oils into the human skin in vivo

Using the in vivo confocal Raman microscopy (CRM), Stamatas et al. [1] reported that the maximum penetration depth of vegetable oils and paraffin oil into the stratum corneum (SC) does not exceed 10μm, whereas petrolatum exhibits an enhanced penetration capability extending to 30μm, i.e. SC thickness. These results are in contrary to the generally accepted opinion that petrolatum does not penetrate through the SC and that the high occlusion effect of petrolatum is a result of skin surface covering which substantially impedes the water evaporation [2,3].