214 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS products. Thus the shampoo was applied to the skin, diluted with water and the excess, after varying periods of contact, was rinsed away. The aerosol on the other hand was applied and allowed to dry on the skin. The penetra- tion of [all] Triclosan from the shampoo was 0.197 lag cm -2 and was 6.85 lag cm -2 from the aerosol, or some thirty times more in favour of the aerosol at these particular product concentrations of [all] Triclosan. Even at com- parable concentrations of [aH] Triclosan (i.e. 0.1• (w/v)) the penetration is still some eleven times greater from the aerosol. Thus, the composition and mode of use of different products containing [aH] Triclosan is very important in determining the extent of penetration of the germicide. Based on the work described by Feldman and Maibach (7), Maibach eta/. (8) and Bartek, Labudde and Maibach (9) together with the data collated by Tregear (10), we consider that the permeability of rat skin may be similar to that of human scalp and axilla. Using the experimental data obtained from the present rat experiments together with a no-effect level from a 3-week target organ test in the rat of 200 mg kg -• day -1 (unpublished observations) we can make calculations of the safety-in-use of Triclosan for the average woman of 55 kg body weight. Assuming the area of the scalp and hands is 1350 cm 2, then for a penetration of 0.197 lag cm -2, the absorbed dose is 4.8 lag kg -•, which is 42 000 times less than the no-effect level observed in the target organ test. The highest concentration of [all] Triclosan gave a minimum of 1000 times less than the no-effect level. From the aerosol deodorant if the spray is used twice daily for 2 s on each axilla of 50 cm •, then the absorbed dose, at 6.85 lag cm -2, is 24.9 lag kg -1 which is 8000 times less than the no-effect level in the target organ test. Thus, we conclude on the basis of the percutaneous absorption and toxicity data available, that extremely small proportions of the no-effect level of Triclosan are likely to be absorbed through adult human skin treated with shampoo containing 0.05•o (w/v) Triclosan or with an aerosol deodorant containing 0.1 •o (w/v) Triclosan. ACKNOWLEDGMENTS It is a pleasure to acknowledge the skilled assistance of Mr C. T. James and Mrs A. J. Cordell. (Received: 1st April 1974)

PERCUTANEOUS ABSORPTION OF TRICLOSAN 215 REFERENCES (1) Black, J. G., Sprott, W. E., Howes, D. and Rutherford, T. Percutaneous absorption of hexachlorophene. Toxicology 2 127 (1974) (2) Curley, A., Hawk, R. E., Kimbrough, R. D., Mathenson, G. and Finberg, L. Derreal absorption of hexachlorophene in infants. Lancet Aug 7 296 (1971). (3) Ulsamer, A. G., Yoder, P. D. and Marzulli, F. N. Determination of hexachlorophene in human and experimental animal tissue. Toxicol. Appl. Pharmacol. 22 276 (1972). (4) Lyman, F. L. and Furia, T. Toxicology of 2,4,4Mrichloro-2•-hydroxy diphenyl ether. Ind. Meal. 38 45 (1969). (5) Black, J. G., Howes, D. and Rutherford, T. Percutaneous absorption •tnd metabolism of Irgasan DP300. Toxicology 3 33 (1975). (6) Vickers, C. F. H. Dam, reservoir or filter. Trans. St. John's Hosp. Dermatol. Soc. 59 10 (1973). (7) Feldman, R. G. and Maibach, H. I. Regional variations in percutaneous absorption of •4C-cortisol in man. J. Invest. Dermatol. 48 181 (1967). (8) Maibach, H. I., Feldman, R. J., Milby, T. H. and Serat, W. F. Regional variation in per- cutaneous penetration in man. Pesticides. Arch. Environ. Health 23 208 (1971). (9) Bartek, M. G., Labudde, J. G. and Maibach, H. I. Skin permeability in vivo: comparison in rat, rabbit, pig and man. J. Invest. Dermatoi. 58 114 (1972). (10) Tregear, R. T. Physical Femctions of Sicin p. 12 (1966) (Academic Press, London).