Diatomaceous Earth

Diatomaceous earth is an insoluble, abrasive mineral powder used in cleansers, masks, and tooth products (often a few percent up to higher levels in polishing formulas), and its primary risk is mechanical irritation rather than chemical reactivity. Clinical and practical patch/usage experience show it can provoke stinging, dryness, and worsening of eczema or barrier-compromised skin due to frictional microtrauma, especially with repeated use or in leave-on masks. Given the meaningful risk in sensitive populations and cumulative irritation in routines that already include actives, it merits a moderate irritancy score with patch testing advised. Safety Notes: In commercial skincare, diatomaceous earth is used at low levels (~0.1–2%) as an absorbent/mattifying or mild texturizing powder in leave-on creams, lotions, primers, and masks. Higher levels are seen in rinse-off exfoliating/cleansing formats and powder-to-paste products (scrubs, mask powders, cleansing powders), where it can function as a primary abrasive/bulking phase commonly around 10–40%, with specialty consumer-available exfoliant powders reaching ~50–60%. There is no specific EU/FDA cosmetic concentration limit for diatomaceous earth itself, but practical limits are driven by texture/abrasivity, dusting/inhalation risk for powders, and sensory tolerability (leave-on products generally stay at the low end).