SKIN SAFETY OF HEXACHLOROPHENE ....• *• .... : .... • •- •.:* r4 ?' 7,, •. •--.•,..• .../• .... •.. • • ... .... •. ..•.:• --•.: .. '•7- •:. •:. a .... •......•,• •: ]:: •.. ,- 7, .-• . • -:. , .•.t . -"•. :• . • • •'--- :.. •. •.• •:.•-.!:.• • .•-• :• .:' : .• ... • '• " :• ..-•..• - 1 DAY ' :' Figure 6. Histological findings of primary irritant reactions to HCP 1, 2, 3, and 4 days after application

126 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS REACTION NUMBER OF HCP GUINEA PIG '1 100- UV (-I • •1 RABBIT UV (+l I lOO 1.00 0.50 0.25 0.10 0.05 1.00 0.50 0.25 0.10 0.05 CONCENTRATION (%) Figure 7. Phototoxity of HCP in acetone DISCUSSION The authors examined HCP for safety to the skin by using experimental animals and man. HCP had a distinctly more potent primary irritaney poten- tial upon animal skin than any other halogenated compound studied. On the other hand, it was impossible to find any contact or photocontact sensitization with HCP. In 1969, Baker (19) reported 9 human cases with scrotal dermatitis and 1 case with buttock dermatitis caused by primary irrita- tion with HCP. All cases were produced by a bath preparation containing HCP, except one which was caused by application of a skin cleanser contain- ing this chemical. It is said that ff a substance to which there is a low barrier resistance is applied continually, the mild irritant activity will have a cumulative effect, which gradually induces a fatigue phenomenon of the skin. Willis and Kligman (17) mentioned that HCP and other halogenareal compounds remained in the cutaneous tissue for a considerably long time after having been in contact with the skin. Therefore, these points must be taken into full considcration •vhen a preparation containing HCP is used continually. Our experiments on animals and humans indicated that the primary irritant reaction of HCP is influenced markedly by the kind of vehicle used as seen in Table VI. The irritant reaction of HCP was readily produced in guinea pigs and rab- bits applied with this chemical dissolved in acctone. On the other hand, it was hardly induced in those animals administered with this chemical dissolved in polyethylene glycol 400. It was more easily induced in humans applied with