Pumice

Pumice is an insoluble mineral abrasive used in scrubs, soaps, and foot/body exfoliants, and its irritancy risk is driven by mechanical friction rather than chemical reactivity. In sensitive or eczematous skin, abrasive particles can create microtears and barrier disruption, commonly provoking stinging, erythema, and flare-ups—especially with frequent use or concurrent actives (acids/retinoids). Because this injury mechanism is predictable and clinically relevant in compromised skin, it warrants a significant irritancy score despite low sensitization potential. Safety Notes: In commercial skincare, pumice appears at very low levels (~0.1–1%) in gentle daily facial scrubs/cleansers where it functions as a light physical exfoliant alongside other abrasives or polymers. Typical rinse-off body/foot scrubs commonly use ~5–30% depending on desired scrub intensity and viscosity. The highest consumer-available concentrations are found in anhydrous or paste-like heavy-duty foot/hand “pumice scrub” products and mechanic-style cleansers where pumice can be the dominant solid phase (about 50–80%); it is overwhelmingly used in rinse-off formats due to grit/abrasion and poor suitability for leave-on products.