PERCUTANEOUS ABSORPTION OF COSMETIC OILS 277 Figure 9. Microautoradiograms showing the distribution of radioactivity within the skin of Angora rabbits at various times after 24 hr topical application of •4C-HDO. A) intact skin, B) zero day, C) one day, D) three days, E) six days, F) ten days. Note the changes of concentration in the sebaceous glands and dermis plotted against time, which indicated that radioactivity remaining in the injected site was reduced to 43% at 24 hr and 20% at 72 hr for IPM, while HDO remained 42 to 43% at 24 and 72 hr. Figure 12 shows the scanning curves of thin layer radiochromatograms of the extracts where no metabolites were found even after 72 hr for both oils. These results sug- gested that irritation was caused by the applied substances themselves and not by their metabolites in the case of IPM and HDO.

278 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS '• -- '•- •.• ' . - : •.• ' / ' :•l•.,":. ' e.: ..•z•_• - - - •.* - •. ,•..• • ..... .- ••- •.• •.. e . •. • . ... .. ' - ' /'7--5 , - :• - ., L • •. •-•- . ". • i * • • '• '.• '" ..... • • •.• • .... •.• .... ,r•. •½..• ½..,½• %, , c-' '.7 '-"----'":' "c ........ .. ... • •-.•.• ,- ,•, ..•.. •. '-½•. ',. -.• •7•T .: . .:. •"•Z'•.½ ..• . • 'z?.•½"•*'• .• ' • '•.• --' ' '---*-• • - - - • * • ,•'• . : . , ...... • . .. .. •.. . ...• . .. Figure 10. Light micrographs showing the bistological feature within the skin of Angora rabbits at various times •ter 24 br topical application of •C-•DO. A) intact skin, B) zero day, C) one day, D) three days, E) six days, F) ten days. The changes of acantbosis in the epidermis and edema and vasodilatation in the dermis were obse•ed DISCUSSION Whole body autoradiography is a useful method since it can visualize the behavior of an applied material in the body and its possible metabolic routes then estimated. Figure 13 from our previous paper (20) showed autoradiograms of percutaneously absorbed •4C-hexachlorophene where the isotope was accumulated in the liver and excreted through the gallbladder to the small intestine at 6 hr after topical application. Such a well absorbed material gives a clear autoradiographic feature. However it is not avail- able for the materials of low percutaneous absorbability as shown in Figure 1. Besides,