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.

532 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Multiple Washing--1 Day Period Number of Washings Concentration on Skin (v/cm 2) 2.0% Hex. Soap 1.0% Hex. Soap 9 3.2 1.8 12 3.9 1.9 16 4.0 2.3 20 4.7 2.6 Table VI Single Washing--Extended Time Periods Length of Time of Soap Application (minutes) Concentration of Hexachlorophene on Skin (v/cm 2) 0.25 1.3 2.0 2.3 4.0 3.6 8.0 5.2 Single Application--Extended Washing Time The accumulation of hexachlorophene on the skin was measured using a single washing with varying time periods for the application of the soap. The arms were washed with a 2.0% hexachlorophene soap for periods up to eight minutes, rewetting the soap every two minutes. The arms were then lathered and rinsed, and the hexachlorophene was extracted in the usual manner. Analysis of these extracts, listed in Table VI, clearly indicated a marked increase in the amount of hexa- chlorophene left on the skin with increased time of application of the soap. Bath rs. Shower Tests Skin retention tests were conducted comparing a shower to a bath rinsing procedure. Exactly 1.0 g of a 2.0% hexachlorophene soap bar was applied to each of the forearms with frequent intermittent rinsing until the entire soap sample had been consumed. Rinsing by shower was accomplished by spraying warm water from a shower head over the arm. The bath rinse consisted of immersion of the arm in a pan containing 3000 ml of water with a final four-minute soaking in this