R. Gfatter et al., EFFECTS OF SOAP AND DETERGENTS ON SKIN SURFACE PH, STRATUM-CORNEUM HYDRATION AND FAT-CONTENT IN INFANTS, Dermatology, 195(3), 1997, pp. 258-262
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.