PETROLATUM AND COMEDOGENICITY 43 archetypical hydrophobic grease, and (2) it is widely used in a great variety of topical products for varied purposes. It behooves us to have accurate information about its potential for producing adverse effects. METHODS SUBJECTS AND TREATMENTS Paid volunteers were recruited from a single district in South Philadelphia. Each par- ticipant had persistent, moderate acne of at least two years duration. The criteria for entry was at least ten papulo-pustules and 15 comedones. Both mild and severe cases of acne were excluded. There were two groups of ten each. In each group there were six males and four females, with an average age of about 18 (range 14 to 22). A variety of OTC products had been used by most subjects with varying efficacy. Anti-acne medications were stopped one month before starting the study. One group received a product consisting of a highly refined petrolatum, twice daily, to the entire face for eight weeks. The second group received a cream product that is an aqueous emulsion containing 30% petrolatum. The identity of the products was masked to the subjects by putting the contents into new unmarked jars. The volunteers were told that the treatments, though greasy, might be beneficial in soothing acne. We indicated that the use of oily formulations in acne was a new approach and that this was a preliminary study to evaluate efficacy. The subjects were paid a modest fee for their participation. We showed each subject how to apply a pea-sized amount to both sides of the forehead, followed by spreading with the fingers over the entire face. The face was washed with a mild soap prior to each application. The study was carried out in the winter months, when the greasiness of the products would be less discomforting. OBSERVATIONS Lesion counts of the entire face were made at baseline and after eight weeks. A derma- tologist experienced in the method counted all comedones, open and closed, recording these together as a single category. Likewise, papules were not separated from pustules, and were simply categorized as papulo-pustules. Microcomedones were estimated by the cyanoacrylate follicular biopsy technique at 0 and 8 weeks, following the quantitative image analysis methodology of Pagnoni and Kligman (11,12). Briefly, a drop of cyanoacrylate (Krazy Glue) was applied to the mid-forehead and spread out under a plastic slide. After hardening of the polymer in about two minutes, the slide was gently lifted off, carrying with it a thin sheet of the outer horny layer with attached veilus hairs. Those hairs that were encased by horny casts as observed under the stereomicroscope were considered to be microcomedones. The density of microcomedones was expressed as the number per square centimeter. Global estimates of improvement were made by the subjects and by the dermatologist

44 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS at 0, 4, and 8 weeks, using the following grading system: worse, no change, slight improvement, moderate improvement. STATISTICS Changes in lesion counts from baseline were assessed by Student's t-test. RESULTS Changes from baseline are shown in Figure 1 for microcomedones, visible comedones, and papulo-pustules. A slight but insignificant decrease in visible comedones was noted in both groups. Likewise, the slight decrease in the density of microcomedones was not statistically significant. By contrast, in both groups papulo-pustules decreased significantly (p = 0.05). Global self-assessments yielded the following data: PETROLEUM JELLY: ß Three recorded no change. ß Six recorded slight improvement. ß One recorded moderate improvement. 20 Mean 10 T Comedones Papulo-pustules Microcomedones Week 0 Week 8 20- Vaseline Petroleum • Week 0 15- • Week 8 Mean 10- 5 T 0 Comedones Papulo-pustules Microcomedones 'Jr P= .05 Figure 1. Effect of petrolatums on acne lesion counts after twice-daily applications for eight weeks. Coinedones were not affected. Both products significantly reduced papulo-pustules.