CUTANEOUS EFFECTS OF DEAD SEA MUD 275 mud showed lower TEWL directly after mud removal. Dead Sea minerals are considered hygroscopic and may play a role in attracting and retaining the water content of the up- per epidermis similar to the role played by natural moisturizing factors (NMF). NMF consist of lactate, amino acids, and pyrollidone carboxylic acid and are present inside the corneocytes. They are necessary to maintain proper hydration of the stratum corneum because of their water-loving characteristics (10). In addition, although the gel and over-the-shelf mud caused a comparable increase in skin hydration directly after their removal, forearms treated with over-the-shelf mud showed lower TEWL directly after their removal (Figure 4). One factor that may retain absorbed water in the stratum corneum and slow its loss from skin is the humectants in the formu- lation that penetrated into the skin. The presence of glycerin as a humectant in moistur- izers decreases TEWL with an increase in skin hydration by retaining applied water on or immediately below the surface of the stratum corneum (11). Apparently, water evaporation is slowed by the retention of water in the skin by added glycerin in the over-the-shelf mud. The effect of humectants on skin care products is known to enhance the skin hydration capacity of the applied product. Thus, boosting DSM with other ingredients can enhance its effect on skin barrier properties. “As Is” mud, salted mud, over-the-shelf mud, and gel did not cause dramatic changes in skin pH after application. Skin pH remained acidic up to 60 min post-removal and was comparable to the untreated forearm values at all tested time points, as shown in Table III. CONCLUSION Thirty-minute single application of various types of DSM did not cause any detectable damage to skin integrity. The mildness of the mud was confi rmed by the lack of any Figure 2. Erythema levels for forearms treated with “As Is” mud (n = 20), salted mud (n = 20), over-the-shelf mud (n = 20), and gel (n = 15) at baseline, directly, 30 min, and 60 min after mud removal. Values repre- sented as mean ± SEM.

JOURNAL OF COSMETIC SCIENCE 276 marked differences in skin erythema and pH in the treated forearm skin as compared with baseline values. In addition, the short-lived increase in TEWL directly after mud removal confi rms no negative impact of mud on skin integrity. Furthermore, the results showed a short-lived hydration effect of DSM on skin and the importance of boosting the mud with other valuable additives to enhance its skin hydration benefi ts. Figure 3. TEWL for forearms treated with “As Is” mud (n = 20) (A), salted mud (n = 20) (B), over-the-shelf mud (n = 20) (C), and gel (n = 15) (D) at baseline, directly, 30 min, and 60 min after mud removal, compared with untreated forearms. Values represented as mean ± SEM. Figu re 4. Changes in skin hydration (Δhydration) and TEWL (ΔTEWL) from baseline values for forearms treated with “As Is” mud (n = 20), salted mud (n = 20), over-the-shelf mud (n = 20), and gel (n = 15) directly after mud removal. Values represented as mean ± SEM.