DEPOSITION OF HEXACHLOROPHENE ON SKIN 529 Hexachlorophene Concentration ill Soap (%) 0.25 0.50 I 0 2 0 50 Table II Single Washing Hexachlorophene Concentration on Skin (T/cm 2) 0.15, 0.29, 0.31, 0.32 0.42, 0.42, 0.45, 0.47, 0.47 0.52, 0.65, 0.74, 0.81, 0.82 0.82, 0.84, 0.90, 0.92, 1.02 0.90, 0.95, 1.02, 1.05 1.09,1 19,1.19,1.29 1.34, 1 35, 1.42, 1.47 1.94, 2 74, 3.39, 3.55 3.55,3 71,4.03,4.35 Plastic gloves were fastened on both hands, the arms were moistened with warm water, and the test soap was applied by rubbing all areas of the forearm from wrist to elbow for fifteen seconds. The arm was then lathered for thirty seconds and rinsed with 1500 ml of warm water. Immediately after rinsing, the arm was immersed in 1000 ml of alcohol and the extract condensed and analyzed as previously described. Most of the tests in this investigation were conducted on the forearms of the same two subjects. Occasionally, additional subjects were included for a single test and in every instance produced comparable data to the stand ard subjects. Results of single washings with bars containing various concentra- tions of hexachlorophene are listed in Table II. Each figure represents the quantity recovered from an arm after one washing with the specified soap bar. The data are recorded as micrograms hexachlorophene per square centimeter of skin, using 620 sq cm as the approximate area of forearm skin. A minimum period of forty-eight hours was permitted to elapse after each test before an arm was re-used. These results show that the higher the hexachlorophene content of the bar the greater the deposition on the skin. Despite some spread in the results for a given soap and the slight overlapping between the 1 and 2% bars, each of the test soaps can be differentiated from another by the quantity of hexachlorophene deposited. The amount of hexachlorophene retained by the skin from the various soaps was directly compared in a series of repetitive tests. Different arms were washed at the same time with bars containing 1, 2, and 5% hexachlorophene, and the quantity left on the skin was determined.

530 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Hexachlorophene Concentration in Soap (%) Table I I I Single Washing--Replicate Tests Hexachlorophene Concentration on Skin (T/cm 2) Test 1 Test 2 Test 3 Test 4 Test 5 1.0 1.00 1.15 2.0 1.55, 1.42" 1.65, 1.47 '• 5.0 2.90 3.03 Blank ...... Two arms tested with 2.0% hexachlorophene soap. 0.81 0.63 0.77 1.40 1.08 1.50 2.60 2.32 2.58 ... 0 0 Table IV Multiple Washing 4 Day Period Hexachlorophene Concentration in Soap (%) Hexachlorophene Concentration on Skin (T/cm 2) 1.0 1.7 (0.82 2.0 3.5 (1.19) 5.0 0.4(a.55) 10.0 15.5 Numbers in parentheses are medians of results obtained from one washing (Table II). This test was repeated four times on four different days. At least forty- eight hours lapsed between tests. Results in Table III show that within each test run there is an increase in hexachlorophene deposition as its content in the soap increased. However, this relationship is not neces- sarily present if isolated data from one test are compared to another for example, the 1% bar in Test 2 deposited more than the 2% bar in Test 4. This discrepancy apparently stems from the fact that all of the test soaps deposited their lowest quantities in Test 4 and their highest in Test 2. This is illustrated in Fig. 1. Therefore, the comparative effects of different soaps is best determined by tests conducted at the same time. Multiple Washings--Four-Day Periods Tests were conducted in which the arms were washed with soap bars six times over a four-day period and the hexachlorophene retained by the skin determined after the sixth application. These results, listed in Table IV, show a significant increase in the quantity deposited by all bars compared to a single application (see Tables II and III).