Absorption of boric acid through human skin depending on the type of vehicle.

Three per cent boric acid incorporated in an anhydrous, water-emulsifying ointment causes no increase of boron levels in blood and urine during a period of 1-9 days after a single topical application. The same amount of boric acid incorporated in a water-based jelly does cause an increase in blood and urine levels, beginning within 2-6 h after application. The decisive factor is the degree of liberation of boron from the vehicle. Skin conditions, such as erythema, eczema, or psoriasis are of minor importance to boron skin permeability, as compared to the characteristics of the vehicle. Blood levels and urine excretion of boron depend on the daily uptake of boron through food.