What it is
Sodium ferrocyanide is the sodium salt of the hexacyanoferrate(II) ion, an iron-cyanide complex in which the cyanide is tightly bound within a stable coordination structure rather than free. In cosmetic and personal-care use it functions chiefly as an anticaking agent, keeping powdered or pigmented materials free-flowing, and can be associated with the production and stabilization of iron-based blue pigments. It appears at very low levels in formulas such as the listed sunscreen.
Safety & warnings
Although the name contains cyanide, the cyanide in sodium ferrocyanide is locked within a stable iron-cyanide complex and is not present as free cyanide under normal conditions of use; it is used at very low levels and is not regarded as a skin sensitizer or comedogen at those levels. It is not a recognized fragrance allergen.
Origin & sourcing
Synthetic. It is manufactured as an inorganic coordination compound of iron, cyanide, and sodium.
Questions everyone asks
Is sodium ferrocyanide dangerous because it contains cyanide?
The cyanide is tightly bound within a stable iron complex and is not released as free cyanide under normal use, and it is used at very low levels in cosmetics.
Why is it in a sunscreen?
It typically serves as an anticaking agent and can be linked to the stabilization of iron-based pigments used for color.