544 JOURNAL OF COSMETIC SCIENCE and by enumeration. When growth conditions were against collagen swelling, and at given ionic strength observed, predictive microbiology models were used to (I = 0.4 mo! L- 1 ) swelling attains half values compare to assess quantitatively for the ethanol effect. Primary swelling at low ionic strength (I= 0.06 mo! L - 1 ). There modelling of kinetics was performed to determine growth are characteristic concentrations of both surfactants and rate values secondary modelling was performed on these their mixtures (c, r.o 0.5 - 1.0 mmol L- 1 ) that do not growth rates as influenced by ethanol, and minimum produce swelling. It is assumed that this range of inhibitory concentrations of ethanol were determined for concentrations corresponds to amount of surfactants bound each strain. Staphylococcus aureus strains were more to collagen through electrostatic forces and thus to resistant to ethanol than P. aeruginosa strains, in growth temporary increase in fibre hydrophobity. conditions as well as in inactivation conditions. Furthermore, clinical S. aureus strains were more resistant than the collection strain. The method was promising for management of microbiological safety in cosmetics. Interaction of mixture of anionic surfactants with collagen J. Krejci Effect of fluid intake on skin physiology: distinct differences between drinking mineral water and tap water S. Williams, N. Krueger, M. Davids, D. Kraus and M. Kerscher Division of Cosmetic Sciences (FB 13), University of Hamburg, Martin-Luther-King Platz 6, D-20146 Hamburg, Faculty of Technology, Tomas Bata University in Zlin, Germany nam. TGM 275, 762 72 Zlin, Czech Republic Professor Martina Kerscher, MD, Division of Cosmetic J. Krejci, Faculty of Technology, Tomas Bata University in Zlin, nam. TGM 275, 762 72 Zlin, Czech Republic. Tel.: +420 576 031 526 Fax: 420 577 210 172 e-mail: krejcij@ft.utb.cz Sciences (FB 13), University of Hamburg, Martin-Luther­ King Platz 6, D-20146 Hamburg, Germany. Tel.: +49 40 42838 7235 Fax: +49 40 42838 2592 e-mail: martina.kerscher@uni-hamburg.de Study focused on interaction of collagen fibres of collagen 1 Part of this study was presented as a poster on the 64th I with anionic surfactants sodium dodecylbenzene Annual Meeting of the American Academy of sulphonate (SOBS), sodium dodecyl sulphate (SOS) and Dermatology, 3-7 March 2006 in San Francisco, CA, USA. their mixtures at pH = 6, at two ionic strengths (I = 0.06 mo! L -i and I = 0.4 mo! L - 1 ) and laboratory It is generally stated that drinking plenty of water has a temperature. Surfactants and their mixtures were positive influence on skin condition. However, there is no characterised by their critical micelle concentration The aim of our exploratory 'before-after' study was to (c.m.c.), composition of mixed micelles and interaction evaluate the in vivo influence of drinking more than 2 L of factor � according to Rubingh. Dependency of c.m.c. on mineral water or ordinary tap water per day on skin mixture composition has an opposite tendency at both ionic physiology. Ninety-three healthy subjects were included in strengths, which proves the greater influence of added our prospective study. After an initial run-in phase of electrolyte on behaviour of SOS than of SOBS. Interaction 2 weeks to monitor individual drinking habits, subjects had was evaluated by means of binding isotherms and mass to drink 2.25 L day- 1 of either mineral water (n = 53) or swelling degree Clm- The bound quantity partly depends on tap water (n = 40) for 4 weeks. Bioengineering in vivo mixture composition, partly on ionic strength. SOS and measurements on the volar forearm included sonographic mixtures containing its greater quantities are bound more evaluation of skin thickness and density, determination of than SOBS (approx. 150% related to SOBS). Increased skin surface pH, assessment of skin surface morphology, ionic strength of the environment increases bound quantity and measurement of finger circumference. Eighty-six in approximately same manner, heedless of adsorbate subjects completed the study. In the mineral water group composition. Even composition of the mixture after measurements revealed a statistically significant decrease interaction with fibres does not markedly alter from initial in skin density. Skin thickness increased slightly, albeit not composition. Fibre swelling is affected by composition of at a statistically significant level. However, when swelling mixture similarly to binding - it increases with separately analysing those individuals from the mineral growing quantity of surfactants. Greater ionic strength acts water group, who had routinely drunken comparably little

ABSTRACTS 545 before the start of the study, their skin thickness increased a statistically significant increase. Objective skin surface at a statistically significant level. Skin surface pH remained morphology did not change in any group. In summary, almost unchanged in the physiologically optimal range. In drinking more than 2 L of water per day can have a the tap water group, skin density increased significantly, significant impact on skin physiology. The exact effects while skin thickness decreased significantly. Skin surface within the skin seem to differ depending on the nature of pH decreased at a statistically significant level. While in the the water ingested. Randomized, controlled, double-blind mineral water group finger circumference decreased follow-up trials are warranted to confinn the findings of significantly, measurements in the tap water group revealed our exploratory pilot study.