EFFECTS OF SOAP AND DETERGENTS ON SKIN SURFACE PH, STRATUM-CORNEUM HYDRATION AND FAT-CONTENT IN INFANTS

Background: In adults the influence of cleansing preparations on the p H, fat content and hydration of the skin is well documented. Studies i n newborn and small infants have not been reported. Objective: Our stu dy aimed at examining whether similar effects can be ascertained in in fants. Methods: Infants without skin disease, aged 2 weeks to 16 month s, entered an open, controlled and randomized study. Ten infants each had skin washed with tap water (control group), liquid detergent (pH 5 .5), compact detergent (pH 5.5) or alkaline soap (pH 9.5), The pH, fat content and hydration were measured before and 10 min after cleansing , Findings were statistically evaluated by parametric covariance analy sis. Results: The skin pH increased from an average of 6.60 after clea nsing in all groups, The smallest increase (+0.19) was observed in the control group, the largest (+0.45) after washing with alkaline soap. After treatment with liquid or compact detergent, the increase of the pH was only 0.09 higher than for the control group. In comparison to t he compact and liquid detergents, the alkaline soap group had a signif icantly higher increase in pH. The fat content (mean starting value: 4 .34 mu g/cm(2)) decreased after washing in all groups; the smallest ef fect was observed in the control group (decrease of 0.93 mu g/cm(2)), the highest for the alkaline soap group (decrease of 4.81 mu g/cm(2)). In comparison to the compact and liquid detergents, the alkaline soap group had a higher decrease in fat content. This difference was signi ficant for compact detergents, No statistically significant difference s were observed for hydration before versus after washing, Conclusion: Each cleansing agent, even normal tap water, influences the skin surf ace. The increase of the skin pH irritates the physiological protectiv e 'acid mantle', changes the composition of the cutaneous bacterial fl ora and the activity of enzymes in the upper epidermis, which have an acid pH optimum, The dissolution of fat from the skin surface may infl uence the hydration status leading to a dry and squamous skin.