116 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS cording to the method previously indicated. Twenty-four hours after depila- tion, 0.03 ml of a 1% HCP solut'_on in acetone was applied topically to each of four sites on the back of the guinea pig. Tissue spedmens were taken by the skin punch biopsy method from the four sites of application after 1, 2, 3, and 4 days, respeet'_vely. Each sample was fixed in 10% formalin solution, embedded in paraffin, and cut into sections 7/x in thickness. The sections were stained with hema- toxylin and eosin and examined under a microscope at a magnification of 100 and 400 X. Examination of Phototoxicity of HCP in Animals The animals were those tested for primary irritation. A similar procedure was used to depilatate the skin. Twenty-four hours following depilation, two of the following concentrations such as 1, 0.5, 0.25, 0.1, 0.05, 0.01% of HCP dissolved in acetone were applied symmetrically on both sides, left and right, of the depilated area to circles 1.5 cm in diameter. Immediately after applica- tion, the area on one side was covered with aluminum foil. Thirty minutes later, the other side was irradiated with four fluorescent lamps* (for irradia- tion of ultrav'•clet rays at a wavelength of 300-400 mR, with a peak at 360 m/•) xvhieh had been e(luipped with an ordinary glass filter to eliminate the w,•velenc th vlthin the range of sunburn. The distance from the light soume to the skin was 10 cm. Irradiation was continued for 3 hours (1.12x 10 s erRs/era2. The test circles were observed for a reaction 24 and 4S hours after the end of irrad ation, The intensity of skin reaction was graded in ac- cordance xvith the criteria shown in Table I. Examination of Contact Sensitization in Animals Male albino gu'nea pigs of the Hartley strain weighin• 400-500 g were used. The nuchal area of guinea pigs was shaved and dipilated as indicated previously. About 24 hours after dcpilation, 0.05 ml of 2% HCP solution in acetone was applied to a site about 2 x 2 cm in size in the nuehal area. This procedure was carried out daily for 5 consecutive days per week and repeated for 2 •veeks. Challenge was performed 2 weeks following the last topical application of the HCP solution. Hair on the back of a guinea pig was cut by the electric hair dipper and immediately depilatated. Twenty-four hours after depilation, 0.05 ml of 0.001, 0.01, 0.05, and 0.1% HCP solution in acetone was applied topically to sites 2 x 2 em in s ze. The test sites were observed for the presence or absence of a skin reaction and the intensity of the reaction 24 and 48 hours after the procedure of challenge was recorded. The intensity of the skin re- action was graded in accordance with the criteria shown in Table I. *Toshiba Model FL-20 BLB, 72 Horikawa-eho, Kawashi, Japan.

SKIN SAFETY OF HEXACHLOROPHENE 117 Examination o[ Photocontact Sensitization in Animals The animals were the same as mentioned for contact sensitization. Twenty- four hours following depilation, 0.05 ml of 9,% HCP solution in acetone was applied topically to a site about 9, x 9, cm in size on the nuchal area of the animal. About 30 minutes later, this site was exposed to ultraviolet rays. The light source used was composed of two Toshiba Model FL-20 BLB fluorescent lamps and two Model FL-20 SE fluorescent lamps (for irradiation of ultraviolet rays at a wavelength of 9,70-400 m/x) arranged alternately. The distance from the light source to the skin was 10 cm. The energy used was 1.18x 108 ergs/cm •. This procedure was carried out daily for 5 con- secutive days per week and repeated for 9, weeks. Challenge was performed 9, weeks after the last application of HCP solu- tion. The same procedure as mentioned previously was applied to the skin for depilation. After 9,4 hours, 0.05 ml each of 0.001, 0.01, 0.05, and 0.1% HCP solution in acetone was applied topically to the sites arranged in two rows, as shown in Fig. 1. Immediately, the sites of one row were covered with alumi- num furl to keep the light out. Thirty minutes after topical application, the sites in the other row were irradiated with four fluorescent lamps to which a glass filter was attached to eliminate sunburn. The distance from the light source to the skin was 10 cm. The energy used was 1.19, x 108 ergs/cm •. The test sites were observed for the presence or absence of a skin reaction and the intensity of the reaction 9,4 and 48 hours after irradiation was recorded. The intensity of skin reaction was graded in accordance with the criteria shown in Table I. • •j• "• • SENSITIZED SITE ., Figure 1. Challenge method RESULTS The comparison of primary irritation between hexachlorophene and other halogenated compounds used as bactericides by the open patch tests on animals is shown in Table II. Primary irritation was observed in guinea pigs