Polarised light micrograph of crystals of benzoic acid, a food additive also known with the code E210. Benzoic acid, together with other compounds derived from it such as sodium benzoate, is an anti-fungal agent. It is used to preserve food and fruit juices by inhibiting the growth of moulds, fungi, yeast and some bacteria. Allergic reactions to benzoic acid have been reported and generally concentrations of it exceeding 0.1% are considered to be toxic. It is used in pharmaceutical preparations for the treatment of fungal infections of the skin and also for the production of some cosmetics. Magnification: x10 at 35mm size.