130 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS the presence of PVP. Also PVP prevents separation of cosmetic preparations by acting as a suspending agent to many materials which it cannot carry into water solutions. PVP, when studied in shampoos, acts as a foam stabilizer. PVP has the property of reducing the intensity or delaying the inception of primary irritant effects of many irritants on the skin. The authors have tested over 100 materials commonly used in cosmetic preparations and have found that in the majority of these, the irritant properties are minimized by PVP. For example, both so- dium alkyl sulfonate and sodium N-lauroyl sulfonate tested in a 1% solu- tion by means of the repeated insult patch test study technique showed lq- reactions beginning as early as the third application. Following the fifth application, 2+ reactions occurred in some subjects. However, the same solutions with 1% PVP added, produced no irritation until af- ter the seventh application. The intensity of these reactions remained at the 1 q- level in a greater number of the subjects tested. The detoxifying effect of PVP is something that is made use of consider- ably. The PVP iodine complex referred to previously is a good example of the detoxification of a highly toxic material, namely elemental iodine. The toxicity of iodine is reduced in effect from an approximate LD0 of 150 mgm./kg. to 1500 mgm./kg. PVP will also reduce the toxicity of mercury, nicotine, cyanide, and other such toxic materials. Among the desirable attributes of PVP is the property of substantivity. By substantivity, in this case, is meant the affinity of the PVP for various types of materials, which affinity cannot be explained simply by absorp- tion or adsorption. We might further qualify this phenomenon of substan- tivity as a special type of irreversible adsorption. When hair is placed in contact with PVP solution, or if the PVP solu- tion is added to the hair, certain amounts of the PVP enter into the hair shaft. Subsequent rinsing of the hair does not remove all the PVP which is apparently combined with elements of the lumen of the hair shaft. On microscopic examination, it is apparent that the hair takes on an improved appearance, and an increased clarity, accentuating the natural color. The hair appears to be smoother. Qualitative studies were performed to show that the PVP is present in the hair. By utilizing the PVP iodine phenom- enon it is easy to demonstrate the presence of PVP in the hair by adding a weak iodine solution (Lugols). Enough of the iodine is absorbed by the PVP to give it the mahogany color which is characteristic of the PVP iodine complex. After these hairs are washed, the residual PVP-iodine complex retains its germicidal nature. A further illustration is to be seen in the combination of Actamer and PVP. Five-tenths per cent Actamer dispersions were prepared with and without 5.0% PVP. Thoroughly washed hair (soap and water wash) was added to the Actamer solution in one case, and to the Actamer-PVP

POLYVINYLPYRROLIDONE IN COSMETICS 131 solution in the other case. A contact time of approximately 40 minutes was permitted to elapse. After 40 minutes a small sample of the hair was removed from each tube and the rest of each hair sample was trans- ferred to tubes •)f water. The transferred hair samples were then agitated intermittently for a period of five minutes. A sample of hair from each tube was once again removed and the bulk of the hair samples in each case were then transferred to another tube containing water. In this fash- ion, the Actaruer treated and PVP-Actamer treated hair was washed and sampled for a total of four times, so that there were four hair samples and four washings in each case at the. completion of the successive washing procedures. The above hair samples and washings were then tested for residual Actamet. Staphylococcus aureus agar plates were prepared. Tufts of the above hair samples were placed in the seeded agar just be- fore it hardened. The washings from the same hair samples were added to cups cut in the previously hardened agar in the usual fashion. The results of the above run follow: SIZE OF ZONES OF INHIBITION OF S. aureus •. PVP-Actamer • I-- Actamer • Sample Washings Washings Washings Washings No. Cup Plate Hair Plate Cup Plate Hair Plate 1 8 mm. 40 mm. complete 8 mm• 30 mm. plate 2 5 mm. 8 mm. 7 mm. 4 mm. 3 1 min. 2 mm. 3 min. 0 4 0 2 mm. 1 mm. 0 On the basis of the above results, the successive washings of Actaruer treated hair give greater zones of inhibition than the successive washings of PVP-Actamer treated hair. Likewise, the Actaruer treated hair itself shows a more rapid elution of Actamer by successive washings than does the PVP-Actamer treated hair sample. It follows from the above that PVP results in a more firm fixation of the Actamer. The carrying or solubilizing effect of the PVP was also demon- strated by casting films of Actaruer onto glass slides, from alcoholic solu- tions and from alcoholic PVP solutions. Likewise, hair was treated by spraying with alcoholic Actaruer and alcoholic PVP-Actamer solutions. The alcoholic Actamer solution evaporates with the fortnation of crystals and amorphous precipitates of Actaruer directly on the hair shaft, and on the surface of the glass slides. The alcoholic PVP-Actamer evaporates without any visible precipitate forming on either the surface of the slide or the surface of the hair. Instead a perfectly transparent film is fortned. The above phenomena are effective at low concentrations of the PVP (e.g., 0.5%) since evaporation of the solvent takes place when the hair is sprayed.