j, Cosmet. Sci., 49, 343-350 (November/December 1998) On the influence of bath oils with different solvent characteristics and different amounts of a non-ionic tenside on the hydration and barrier function of the stratum corneum j. w. FLUHR, M. GLOOR, J. BETTINGER, and W. GEHRING, Department of Dermatology, St•idt. Klinik•m, Karlsruhe Germany. Accepted for publication October 15, 1998. Synopsis The research results presented here show the dehydration effect of water baths and oil baths with a high content of a non-ionogenic tenside. Baths of this composition lead to an increase in transepidermal water loss in the sense of slight barrier damage. With oil baths containing a small amount of the non-ionogenic tenside and with even more in spreading oil baths, an increase in the hydration of the stratum corneum and a decrease in transepidermal water loss in an occlusive effect can be proven by contrast. Practical significance of the results of these investigations is gained, especially for patients with atopic eczema. For these patients, the tenside content in a bath oil should be kept low or, better, spreading baths without tensides should be used. INTRODUCTION AND AIM OF THE STUDY Most of the publications on the effect of bath oils in consideration of their tenside content and the character of the oil investigate their influence on skin surface lipids (1-3). Gloor et aL could prove a dependence of the skin surface lipids on the tenside content and the amount of emollients in bath oils (4-6). The lower the amount of tenside in the oil baths and the higher the amount of emollients are, the more skin surface lipids were present. Although the barrier function and the water content of the stratum corneum can be considered to be functions that are dependent on various lipid parameters, the capacity of bath oils with differing tenside content and oil character (dispersion oil, spreading oil) to influence them has not yet been investigated. With the present study, two questions are to be evaluated critically. First: is it possible to achieve an exsiccating effect or to influence the barrier function of the skin negatively by varying the amount of a non- ionogenic tenside in bath oil solutions? Second: Has the character of an oil bath either as a spreading bath or a dispersion oil bath an influence on the aforementioned param- eters? 343

344 JOURNAL OF COSMETIC SCIENCE MATERIAL AND METHODS TEST SUBJECTS AND TREATMENT In this study 15 volunteer test persons were included. They had no pathologic results on the skin sites that were investigated (volar forearm). The measurements were carried out in partly air-conditioned rooms (22øC, 45% relative air humidity). The time for accli- matization was 30 minutes. The age distribution of the nine men and six women included in the study was 20.6 (18-37) years for women and 27.2 (16-35) years for men. The wash solutions used had the following composition: A: Almond oil 30.0 Paraffinum per liqu. 70.0 B: Tween 20 • 18.0 Almond oil 64.0 Aqua purif. 18.0 C: Tween 20 47.0 Almond oil 41.0 Aqua purif. 12.0 Bath oil A was a spreading oil bath, and bath oils B and C were dispersion-type oil baths with differing amounts of tenside. The dilution was 0.2 ml per 500 ml (corresponding to 40 ml per 100 1 of a bath) with luke-warm tap water (35øC) for each formulation. Before the start of each test, the forearms, which were not treated previously, were subdivided in two areas separated from each other by strips of adhesive tape. The test sites were rotated from test person to test person and thereby randomized. An initial value was measured (O-value) to which all further measurements were related. Washing procedure. The washings were performed according to the test procedures of Bettinger eta/. (7): The individuals sites were washed for three minutes with a roll of foam material that was moved back and forth 30 times per minute. After one and two minutes, respectively, the roll was soaked in the bath oil solutions again. No pressure was applied to the skin other than that of the roll's own weight. The forearms were lying horizontally on the padding during the washing procedure. The washing solution was left to incubate on the skin for 15 minutes. Subsequently the first measurement was performed after residues of solution A (spreading bath) were swabbed off with a non-fraying tissue (Kleenex, Kimberley Clark, USA). After the first measurement, we rinsed off the bath oil residues carefully without spilling the solutions from one test site to another. Afterwards the second washing was performed with tap water only, at 35øC, on all four test sites, each with an individual, fresh roll of foam material. Further measurements were performed 30, 60, 90, and 120 minutes after the first washing. • Polyoxyethylene sorbitanmonolaurate DAB 9, non-ionic tenside, Merck, Schuchardt, Hohenbrunn, Ger- many.