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).

DEPOSITION OF HEXACHLOROPHENE ON SKIN Multiple Washings--One-Day Period Previous investigations (4) had demonstrated that the quantity of hexachlorophene retained by the skin reached a "plateau" level after a number of daily washings and remained relatively constant thereafter. An attempt was made to attain a plateau level in a single day by washing the arms with a soap and rinsing every twenty minutes. The tests were conducted with both 1.0 and 2.0% hexachlorophene-containing 3.0 2.0 1.0 COMPARITIVE TESTS SOAP •X•,• x x•X• EX'SOAP •X HEX. SOAP T-I T-2 T-$ T-4 T-5 Figure 1. Deposition of hexachlorophene on skin from soaps soaps. Different arms were immersed in alcohol, the hexachlorophene was extracted after the ninth, twelfth, sixteenth, and twentieth washings, and the quantity deposited was determined. The data in Table V show an irregular but continual rise in the hexachlorophene buildup on the skin as the number of washes increased. No plateau effect could be demonstrated in these tests. The quantity' of hexachlorophene retained from the 2.0% bar was approximately one and one-half to two times the amount retained from the 1.0% soap through the twenty applica- tions.