•. Soc. Cosmetic Chemists, 15• 761-768 (1964) THE RELATIONSHIP BETWEEN DANDRUFF AND THE MICROBIAL FLORA OF THE HUMAN SCALP* By RAYMOND W. VANDERWYK, PH.D.,. and FRANK C. RO•A, M.S.} Presented •une 22-26, 196•, Third Congress International Federation of Societies of Cosmetic Chemists, New York City ABSTRACT A quantitative gravimetric method of measuring the amount of human dandruff scales is described. When the scalps of nine males were treated with an antimicrobial agent for twenty-eight days, a significant lessening in scale (scurf) production was seen. The scalp microbial flora was judged to be one of the factors responsible for scurf production. Dandraft can be controlled by as much as 55% when the microbial flora is eliminated. INTRODUCTION The human scalp provides a favorable environment for the growth of a number of micro6rganisms. It supports those which are lipophilic, kera- tinolytic and saccharolytic. Aerobes and anaerobes flourish equally well. From reports in the literature and from studies carried out by the authors, approximately 25 species of bacteria and 15 species of yeasts have been isolated from the human scalp (1-7). Future studies will probably extend this number, especially since the molds have not been thoroughly investi- gated. Since any combination of organisms might be found on the scalp at any one time, the task of determining the relationship of any one of them to dandruff would be a most difficult one. A logical approach to the question of microbial etiology is to eliminate the microbial flora completely. There- * Research from the Department of Microbiology, Division of Biological Sciences, Massa- chusetts College of Pharmacy, and supported by a grant from John H. Breck Inc. t Massachusetts College of Pharmacy, Boston, Mass. 02115. 761

762 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS upon it must be shown that dandruff fbrmation has been significantly lessened. This would indicate at least a microbial association. The approach suggested here would require frequent and accurate measurements of scurf production correlated with the absence of a scalp microbial flora. Some experimental work along similar lines has been done by Pachtman (7), who found no correlation between the number and type of bacteria on the skin of persons with and those without seborrheic dermatitis. Lubowe (8) concluded that the effectiveness of a dandruff agent is a function of its ability to reduce the number of scalp bacteria and fungi. Both workers estimated the scalp conditions by visual examination. Spoor (9) asserted that the extent to which bacteria infect the scalp is one of the factors which governs dandruff formation. The increasing number of commercial preparations which contain anti- microbial ingredients, and which have been accepted by the public, is recog- nition o(, and possible proof of, their ability to control dandruff. Except for visual observation of changes in the condition of the scalp during clinical trial there are no known methods for measuring the effectiveness in vivo of these preparations. The technique described in this paper measures the changes in weights of scurf samples removed at regular intervals prior to, during, and subsequent to treatment with an antimicrobial agent. Although the method should be of value in the testing of commercial antidandruff products, the purpose of this investigation was to determine what changes in scurf production are brought about by the elimination or radical reduction of the microbial flora from the scalp. METHOD Nine males were selected at random, with no consideration given to their scalp conditions. Each was given instructions to be followed throughout the seventy-three days of the experimental period. I•e was permitted to shampoo his hair with a non-medicated product one week before the begin- ning of the test. Thereafter, shampooing and swimming in chlorinated pools were not permitted. The investigation was divided into four periods. Z. Pre-samp/ing Period (7 Days). During this time any special treat- ment of the scalp was discontinued, and each subject was permitted only to apply tap water to his scalp three times each day. No samples of scurf were removed. 2. Pre-treatment Period (12 Days). During this time the tap water treatment was continued, and samples of scurf were removed three times a week. Treatment Period (25 Days). Each subject was asked to massage one- half ounce of the following antibiotic mixture into his scalp three times a day