Skin surface lipids and hydrophobic soil (SSL)

Skin surface lipids (SSL) are a complex mixture of lipids originating from the sebaceous glands (sebum) and the stratum corneum (epidermal lipids), including squalene, wax esters, triglycerides, ceramides, and cholesterol [1]. Hydrophobic soil refers to exogenous, water-insoluble contaminants such as environmental pollutants, particulate matter, and cosmetic residues that accumulate within the SSL film [2]. Although not a single protein receptor, this lipid-soil complex is a major target for surfactants and dermatological cleansers designed to emulsify and remove debris without disrupting the underlying skin barrier [3]. The biological function of SSL includes maintaining hydration, providing antioxidant protection, and acting as an antimicrobial barrier through the release of free fatty acids [4]. Alterations in the composition or quantity of these lipids are central to the pathogenesis of various skin disorders, including acne vulgaris, seborrheic dermatitis, and atopic dermatitis [5].

Other names

SebumSkin surface filmCutaneous lipidsHydrophobic dirtSkin oils

Surfactant-mediated emulsification and solubilization of hydrophobic components; pharmacological modulation of sebocyte lipid production; topical replenishment of barrier lipids.