Boric acid (H3BO3, boracic acid, orthoboric acid) is a colorless and odorless compound occurring as crystals, granules or a white powder. It is usually prepared by action of sulfuric acid on borax (sodium borate).
Boric acid is used medicinally in ophthalmic solutions, and the powder or solution as an acidifying agent in treating the irritation produced by ammonia from the urine in diapers of infants, and in dermatology in ointments either alone or in combination with other medicinal agents. It has also been employed in gargles, mouth washes and as a preservative.
Commercial uses of boric acid are varied, but often include its use in the preparation of face or body powders in which it is added to tale. It is stated that boric acid has a suppressant effect on molds or mildews, or assists in enabling the powder mixtures to flow more freely from the containers.
The usual ointment contains 10% boric acid; the standard medicinal solution contains not less than 4.25% boric acid.
The United States Food and Drug Administration, on January 30, 1954, issued a statement to the effect that borated talcum powder containing 5% or less of boric acid is safe for use as a dusting powder on babies. The implication here is that powder using more than 5% boric acid would not be safe.
Fatalities among adults from the ingestion of boric acid have been reported from as little as 1 teaspoonful of boric acid. Another report indicates that 2 ounces of a 5% solution of boric acid were fatal to an infant.