156 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS REFERENCES (1) E. A. W. Budge, "Syiac Book of Medicines," Oxford University Press: London, 1913 Vol. 2, p 100. (2) G. Zolotovich and A. Papov, Cosmetics from a Thracian tomb, Soap Perfum. Cosmet., XLII No. 6, p 425, (1969). (3) G. Barker, Solidified sodium stearate-based sticks, Cosmetics and Toiletties, 92, No. 7, p 73 (1977). (4) S. Plechner, "Cosmetics: Science & Technology," Wiley Interscience: New York, 1972, p 408. (5) M. G. DeNavarre, "The Chemistry and Manufacture of Cosmetics," Continental Press: Elizabethtown, Penn., 1975, pp 693-694. (6) R. G. Harry, "Harry's Cosmetics," Chemical Publishing Co., Inc.: New York, 1973, p 272. (7) M. G. DeNavarre, "The Chemistry and Manufacture of Cosmetics," Continental Press, 1975, p 690. (8) S. T. Bowden, "The Phase Rule and Phase Reactions," MacMillan and Co., Ltd.: New York, London, 1950, p 153. (9) F. F. E1-Shimi, In vivo skin friction measurements,J. Soc. Cosmet. Chem., 28, 37-51 (1977).

j. Soc. Cosmet. Chem., 30, 157-165 (May/June 1979) Skin penetration of chemically related detergents j. G. BLACK and D. HOWES Environmental Safety Division, Unilever Research Colworth Laboratory, Sharnbrook, BEDFORD. MK44 1LQ, England. Received June 16, 1978. Presented at Annual Scientific Seminar Society of Cosmetic Chemists, May 1978, Chicago, Illinois. Synopsis Pure [1-14C] labelled alcohol sulphates, alcohol ether sulphates and alcohol ethoxylates with varying chain lengths and degree of ethoxylation were prepared. Aqueous solutions were applied to rat skin, the animals rinsed and a protective patch applied. The excreta and expired air were monitored separately for 48 hr and analysed for radioactivity, from which SKIN PENETRATION was calculated. The animals were killed at 48 hr, the area of treated skin excised and the carcass analysed for residual radioactivity. The data showed that penetration through rat skin in vivo was low for the alcohol sulphates and alcohol ether sulphates, but greater for alcohol ethoxylates. Variation of the alcohol chain length and degree of ethoxylation also affected penetration. Factors such as concentration, duration of contact and repeated application all tended to augment skin penetration to varying extents. It is deduced that absorption of DETERGENTS through human skin is low and that systemic toxic effects are extremely unlikely. INTRODUCTION Historically skin has been regarded as totally impermeable to chemicals and bacteria and it is only within the last 20 years or so that it has become accepted that small quantities of chemicals are able to be absorbed through the skin. During this time both in vitro and in viva techniques have been adopted in attempts to measure skin penetration to understand better the manner of response of skin to topically applied chemicals and to evaluate the possibility of systemic effects. Many investigators have used isolated skin, epidermis or stratum carneurn from human or animal sources to measure transfer of detergents (1-6) or the effect of detergents on the transfer of other molecules (2, 3, 7-12). The conclusions from these studies were that anianic detergents penetrated poorly but prolonged contact or greater concentration increased the permeability of the skin to both detergents themselves and to other substances. Attempts have been made to simulate more lifelike conditions with in vitro studies (13, 14). Most in vitro studies were characterised by an extended lag time of several hours and a poor penetration into the skin, whereas, in viva, a rapid penetration giving measurable blood levels at 15 rain (9) and a deeper penetration into skin were recorded (15). Wahlberg (16) and Howes (6) found little correlation between studies in vitro and on whole animals. 157