EEMCO guidance for the in vivo assessment of skin greasiness

Sebaceous gland activity has four distinct components which are sebum produ ction (a secretion rate function), storage (a volume function), surface out put (a delivery rate function) and stratum corneum permeation (an influx ra te function). The oily appearance of skin results from an excess of sebum e xcretion and spreading over the body surface and its interaction with the s kin surface. A multi-pronged approach is often useful to assess skin greasi ness with precision. The clinical evaluation of skin greasiness and its shi ny appearance should be further complemented by quantifying the large pores , follicular plugs and comedones. The sebum amount present at the skin surf ace can be measured non-invasively using one of several methods based on so lvent extraction, cigarette paper pads, photometric assessment, bentonite c lay and lipid-sensitive tapes. Quantitative parameters include the sebum ca sual level,the sebum excretion rate,the sebum replacement time, the instant sebum delivery, the follicular excretion rate, the density in sebum-enrich ed reservoirs and the sustainable rate of sebum excretion. A series of envi ronmental and biological features influence the data. Hence rigorous method ological designs are mandatory to support claims. As a rule, accuracy of th e methods is adversely affected by skin temperature, degree of hydration an d surface roughness. An additional confounding factor is the inherent diffi culty of collecting the surface lipids without a contribution from the foll icular reservoir. A better understanding of factors that alter the sebum am ount at the skin surface may well assist in the development of sebo-suppres sive agents to help the reduction of the skin greasiness and improve acne. Copyright (C) 2000 S. Karger AG, Basel.