J. Soc. Cosmet. Chem. 26, 205-215 (1975) ¸ 1975 Society of Cosmetic Chemists of Great Britain Percutaneous absorption of Triclosan from toilet preparations J. G. BLACK and D. HOWES* Presented on 26-30th August 1974 in London at the IFSCC VIIIth International Congress on 'Cosmetics--Quality and Safety' organized by the Society of Cosmetic Chemists of Great Britain. Synopsis The absorption of [all) TRICLOSAN (lrgasan © DP300) through RAT SKIN treated with SHAMPOO containing 0.05•o (w/v), and with AEROSOL DEODORANT containing 0.1% (w/v), has been measured. The products were applied in a manner designed to simulate consumer use, and the penetration was calculated from the amount of radioactivity excreted by the animals. From the shampoo, the penetration was 0.197 t•g cm -2 which increased as the concentration of [aH] Triclosan was increased but which was independent of duration of contact with the skin for a given concentration of [all] Triclosan. BLOOD LEVELS at 48 h after treatment were proportional to concentration of applied [aH] Triclosan and for 0.05 •o (w/v) were less than the equivalent of 0.1 •g ml -•. From the aerosol deodorant the penetration was 6.85 •g ml -x and the blood level reached a maximum, equivalent to 0.26 •g ml -•, at 6 h after a single application. The calculated absorption by the human is an extremely low proportion of the no-effect level in rats. INTRODUCTION It has previously been established that small amounts of the germi- cide, hexachlorophene, can penetrate through intact skin (1) and can also be identified in blood, adipose tissue, brain and other body organs (2, 3). The compound 2-hydroxy, 21,4,41-trichlorodiphenyl ether, now called Triclosan and formerly known as Irgasan © DP300 (Ciba Geigy Ltd), has some chemical features in common with hexachlorophene and has been shown to be effective in reducing both Gram positive and Gram negative * Environmental Safety Division, Unilever Research Laboratory, Colworth House, Sharnbrook, Bedford, MK44 1LQ. 205

206 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS bacteria on the skin (4). It has the advantage over hexachlorophene of being of low toxicity (4). Nevertheless, it is important to know the degree to which it could be absorbed through skin from a variety of skin products. We have previously reported on the percutaneous absorption in guinea- pigs of Triclosan from soaps (5) and this present report examines its absorption through rat skin treated with shampoo containing various concentrations of [all] Triclosan and with aerosol deodorant containing 0.1 •o (w/v) [alii Triclosan. The possible absorption by the human of 0.05•o (w/v) Triclosan in a shampoo and of 0.1 •o (w/v) Triclosan in an aerosol deodorant is calculated from the rat data. METHODS Materials Tritiated Triclosan was prepared and purified as described by Black, Howes and Rutherford (5) and had a specific activity of 44.86 gCi mg -x. Samples of [all] Triclosan were accurately weighed out and the shampoo base was added to give concentrations of 0.05, 0.1, 0.5, 1.0 and 2.0•o (w/v) of [3H] Triclosan. The mixtures were stirred at 50øC for 1-2 h to ensure complete solubilization of the germicide. Aliquots of each preparation were counted to determine the precise amount of [all] Triclosan applied to the rats. A single can of aerosol deodorant was prepared by dissolving [all] Triclosan in ethanol and adding the other ingredients to give a concentra- tion of [aH] Triclosan in the product of 0.1 •o (w/v). The can was sealed and the propellant added through the valve from another cannister. ANIMALS AND TREATMENT Subcutaneous turnover of Triclosan Twelve female Colworth-Wistar rats (120 g) were injected with 0.5 ml of [aH] Triclosan solution in 50•o aqueous polyethylene glycol (BDH, Poole, Dorset) under the loose skin over the upper thorax. The animals were placed immediately in the individual metabolic cages for up to 96 h and 24-hourly samples of the separated urine and faeces were collected for determination of tritium. Some rats were killed at 24, 48, 72 and 96 h after being anaes- thetized and heart blood taken.