C20-40 Pareth-40

C20-40 Pareth-40 is a polyethylene glycol ether surfactant/solubilizer used at low-to-moderate levels to emulsify and stabilize formulas; as a nonionic ethoxylated surfactant it is generally well tolerated but not inert. Patch-test data and clinical experience indicate occasional irritant reactions can occur in very reactive or barrier-impaired skin (especially if used in higher surfactant loads or left-on products), but it is typically less irritating than anionic surfactants, supporting a gentle (0.3) score. Safety Notes: C20-40 Pareth-40 is a high-HLB nonionic surfactant/solubilizer and emulsifier (commonly used with fatty alcohols or in gel-cream systems) that appears at very low levels (~0.05–0.3%) in leave-on lotions/serums mainly as a solubilizer or emulsion stabilizer. In richer O/W creams, cleansing creams, and some makeup-remover/balm-to-milk or heavy-duty solubilizing systems available OTC, it is used more materially as a primary emulsifier/solubilizer typically in the 1–5% range, with observed high-strength consumer formulations reaching ~6–8% to keep high oil loads/fragrance or complex actives solubilized and stable. This ingredient is not subject to a specific EU/FDA maximum for cosmetics, so practical stability/sensory limits rather than regulation usually cap the upper end.