LIPID DEPOSITION FROM BATH OILS 301 Table I Bath Oils and Their Dosages (according to the instructions given on the package or leaflet) Name Declared Dosage/20 L composition (concentration) Type AK BD BN EM LF OC OE Mineral oil 91.7% Lanolin oil 3.0% Almond oil 30 g Liquid paraffin 69.6 g Antiox. E320, Aroma, Exc. ad 100 g Soya oil 84.75 ml for each 100 ml Benzylalkonium chloride BP 0.5% w/w Liquid Paraffin BP, 25.0% w/w Isopropyl myristate, BPC 25.0% w/w Paraffin 48.0 g Isooctylpalmitat: Isooctylstearat: Isopropylmyristat 7:2:1 43.99 g, POE Laurinalkohol 6 g, POE-POM Laurinalkohol 1 gad 100 Peanut oil 88.5 g Emulsifiers ad 100 g Liquid paraffin 63.4% w/w, acetylated wool alcohols 5.0% w/w 2.8 ml (0.014%) Dispersing 2.8 ml (0.014%) Floating 4.2 ml (0.021%) Dispersing 4.2 ml (0.021%) Dispersing 4.9 ml (0.024%) Dispersing 4.2 ml (0.021%) Floating 2.8 ml (0.014%) Dispersing oil. The higher PI, the better the "performance" of the oil in depositing lipids on the skin. Of course, no PI could be calculated for control baths. Statistical analysis. Means and standard deviations were calculated in the usual manner. For comparisons and definition of groups, non-parametric variance analysis was used (SPSS-PC+, procedure NPAR TESTS FRIEDMAN). The error level was set at P •o.1. TRANSEPIDERMAL WATER LOSS (TEWL) EXPERIMENTS Four participants volunteered for the second part of this study. On the volar side of their forearms, two sites of approximately 1 x 2 cm were delimited, which corresponded to the center of fields 1 and 3 of the previous experiments. The horny layer was stripped with cellotape until TEWL attained values of 50 to 60 g x m-2 x h-•. After an equilibrium time of 1 h, TEWL was measured again and both forearms bathed exactly as described under "Lipid Deposition Experiments." Only one bath oil was tested (BD, see Table I) the second bath contained only water (control). Measurements, TEWL was measured with the Servo-Med Evaporimeter (Servo-Med, Stockholm, Sweden) just before (0) and 5, 30, 60, 90, and 120 min after bathing. Readings were taken after the probe had been in contact with the skin for approximately 30 s. Calculations. For each measurement, means and standard deviations of TEWL values and of the differences from the values before bathing were calculated.

302 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Forearm Skin Surface Lipids After the Bath Total Field 1 Field 2 Bath oil (mg) (mg) (mg/cm 2) (rag) (mg/cm 2) No (control) 3.0 + 0.4 1.1 + 0.2 0.12 --- 0.02 1.0 + 0.1 0.11 --- 0.01 AK 4.1 + 1.7 1.5 + 0.4 0.16 + 0.05 1.1 + 0.6 0.12 + 0.06 BD 13.2 -+ 5.1 2.4 _+ 1.6 0.26 -+ 0.18 2.9 -+ 1.4 0.32 -+ 0.16 BN 3.8 + 1.7 0.6 + 0.4 0.07 + 0.05 1.0 + 0.4 0.11 + 0.04 EM 2.0 + 1.0 0.6 + 0.2 0.06 + 0.02 0.8 +- 0.6 0.09 + 0.07 LF 6.1 + 4.0 0.9 + 0.6 0.10 + 0.06 0.8 + 0.9 0.09 + 0.09 OC 10.7 + 6.7 2.2 + 2.7 0.24 --- 0.31 1.6 m 1.0 0.18 --- 0.11 OE 3.8 --- 3.0 1.2 + 1.0 0.14 --- 0.11 1.2 --- 0.6 0.13 m 0.06 For abbreviations, see Table I. Means -+ standard deviations of n = 6 forearms. For calculation of the performance index, see Materials and Methods. Statistical analysis. For comparisons, the Wilcoxon matched-pairs signed-ranks test was used (SPSS-PC +, procedure NPAR TESTS WILCOXON). The error level was set at P •o.1. RESULTS There are two factors to consider when investigating the deposition of bath oil from bath water: the first is the total quantity of lipids remaining on the skin the second is the partition of these lipids between skin areas lying deep in the water or near the surface. Table II shows that the behavior of the bath oils is different in both aspects. The quantity of deposited lipids is best appreciated through the total lipids extracted. The variance analysis (Table III) shows that significant differences were found between the bath oils. Two groups could be defined (Table IV): a group with "low" deposition not statistically different from control values, and a smaller group with "high" depo- Table III Non-Parametric Analysis of Variance: Mean Ranks, Chi-Square, and Corresponding P-Values Performance Bath oil Total Field 1 Field 2 Field 3 index No (control) 3.0 4.6 4.6 3.0 -- AK 4.2 6.1 4.2 4.0 4.0 BD 7.4 6.7 6.8 7.5 6.6 BN 4.0 2.4 3.5 4.4 2.8 EM 1.9 2.3 3.1 2.0 1.2 LF 5.4 4.4 2.9 5.7 4.4 OC 6.6 5.3 6.1 6.3 5.4 OE 3.5 4.2 4.8 3.1 3.6 Chi-square 19.98 14.50 11.30 20.33 19.63 P 0.006 0.043 0.126 0.05 0.003 For abbreviations, see Table I.