Sodium Magnesium Fluorosilicate

Sodium magnesium fluorosilicate is an inorganic fluorosilicate salt more associated with industrial uses than leave-on skincare, and salts in this class can be irritating if they contact skin or mucosa, especially when dusted or present at meaningful levels. In sensitive or eczematous skin, ionic/fluoride-containing compounds can provoke stinging and barrier disruption, and safety data for routine cosmetic use are limited compared with standard cosmetic minerals. Given the uncertainty in cosmetic-grade exposure plus the potential for irritation in compromised skin, I score it as a significant irritant risk. Safety Notes: Sodium magnesium fluorosilicate is an uncommon cosmetic ingredient but is observed in a small number of consumer oral-care and occasional deodorant/antimicrobial-type rinse-off products as a fluoride/silicate salt, typically at trace-to-low levels (~0.01–0.2%) when used primarily for ancillary functional effects. Higher-strength OTC products that deliberately target fluoride delivery or stronger antimicrobial/deodorizing claims can reach about ~0.5–1.0%, with practical upper limits driven by taste/irritancy, solubility, and fluoride exposure considerations; it is rarely used in leave-on facial skincare at meaningful levels.