Dicalcium Phosphate

Dicalcium phosphate is an insoluble inorganic salt primarily used as an opacifier/absorbent or mild bulking agent in topical products, and it is generally regarded as low-irritancy because it is not reactive and does not penetrate skin. However, as a particulate mineral it can contribute to mechanical irritation (especially on eczematous or micro-abraded skin) depending on particle size and formula texture, so I do not rate it as fully inert for compromised barriers. Safety Notes: Dicalcium phosphate is most commonly used as an insoluble mineral abrasive/opacifier in rinse-off oral-care style products that are often marketed as cosmetic (toothpastes/powders), where it can appear at very high levels; consumer dentifrices and tooth powders can reach roughly 20–60% depending on form (paste vs powder) and abrasivity targets. In conventional skincare (cleansers, scrubs, masks), it is typically a minor structuring/opacity or gentle polishing aid, often around 0.1–5%, with low-end usage around 0.1–0.5% when included mainly for sensory/whitening or label claims rather than as a primary abrasive. There is no specific EU/FDA cosmetic maximum for dicalcium phosphate; practical limits are driven by texture, sedimentation, and abrasivity considerations, with leave-on products rarely using it above low single digits due to grittiness and film feel.