J. Soc. Cosmetic Chemists, 18, 527-536 (Aug. 19, 1967) Deposition of Hexachlorophene on the Skin MILTON MANOWITZ, Ph.D., and V. DANIEL JOHNSTON, B.S.* Presented N'ovember $0, 1966, New York City Synopsis--Colorimetric analyses of alcoholic extracts of the skin were used to determine the hexachlorophene content of the skin after washing with hexachlorophene-containing soaps. The quantity of hexachlorophene applied was found to be a major factor controlling the amount deposited. Significant quantities of hexachlorophene were left on the skin after soaking in baths containing very low concentrations of the compound. INTRODUCTION Hexachlorophene has been widely used as the antibacterial com- ponent in degerming soaps and detergent formulations. The reduction in the number of bacteria on the skin achieved through the continued use of these products is well documented (1). It is attributed to the buildup of effective levels of the compound on the skin (2). However, determination of these levels has been the subject of very few publica- tions (3-5). The object of this study was to follow the concentrations of hexachlorophene retained by the skin under controlled washing conditions. EXPERIMENTAL ]•xtraction and Analytical Procedures The forearms were selected as the test site since they were accessible, maneuverable, and less exposed to contamination than the hands. The hexachlorophene was recovered from the skin by immersing the arm, * Givaudan Corp., 330 W. Forty-second St., New York, N.Y. 10018. 527

528 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table I Recovery of Hexachlorophene Quantity Concentration Vehicle applied (mg) found (rag) Alcohol Alcohol Alcohol Alcohol Soap Soap Soap 0 50 0 50 0 50 0 50 0 5o 0 50 1 00 52 53 45 46 56 57 04 from wrist to elbow, in a vessel containing 1000 ml of 95% ethanol while gently agitating the solution. The alcoholic extract was concentrated on the steam bath to a volume (10 to 100 ml) suitable for hexachloro- phene analysis. The 4-aminoantipyrine colorimetric procedure was selected as the most suitable method for determining the hexachlorophene in the con- centrated extract. The ultraviolet absorption method, with which this laboratory has had extensive experience, was ruled out. The levels of hexachlorophene were low in many cases, and the UV absorption by skin extracts frequently swamped the absorption by the hexachloro- phene. An ammonia buffer solution (6) was used in place of sodium carbonate described in the literature (7, 8). 4-Aminoantipyrine forms a red color with hexachlorophene in the presence of a mild oxidizing agent. The color density was measured with a Beckman DK2 automatic recording spectrophotometer. The entire absorption curve was scanned so that interferences or turbidity could be observed. Preliminary tests with known amounts of hexachlorophene applied to the skin were conducted to determine the relative validity of these procedures. The hexachlorophene was distributed over the forearms as alcoholic or 5.0% liquid soap solutions and permitted to dry. The arms were then immersed in alcohol, and the extract was condensed to 10.0 ml for analysis. Results of these tests (Table I) demonstrate that quantitative recovery and analyses of the hexachlorophene content of the skin could be made with these procedures. Soap Bar Tests--Single Applications The forearms were washed with soap bars (1•/• X 2j/• in.) containing hexachlorophene using the following general procedure'