Naturally occurring pigments of iron, which can be yellow, red, orange, brown or black in colour.

Manufactured by treating a solution of ferrous sulphate or chloride with an alkali and oxidising the precipitate in hot air. As the iron present in these oxides is in the ferric form it is not very actively available to body tissues.

Can be found in cake and dessert mixes, meat paste, salmon and shrimp paste.

Toxic at 'high doses', banned in Germany.