Water-Holding and Transport Properties of Skin Stratum Corneum of Infants and Toddlers Are Different from Those of Adults: Studies in Three Geographical Regions and Four Ethnic Groups

Abstract

Background/objective: Epidermal structure, function, and composition are different in white infants and adults. We investigated whether ethnicity and location contribute to differences in functional and clinical measurements of skin barrier function during the first years of life and in adults.

Methods: Children (n = 397, ages 3-49 mos) and women (n = 117, mean age 31 yrs) were enrolled at independent centers in Beijing, China (ethnic Chinese), Skillman, New Jersey (white, African American), and Mumbai, India (ethnic South Asian). Water barrier properties of the stratum corneum were assessed using high-frequency conductance and transepidermal water loss (TEWL) on the dorsal forearm and upper inner arm. Digital imaging was used to evaluate facial erythema and scaling.

Results: Despite differences in local climate, TEWL was similar in adults. In children, conductance and TEWL decreased monotonically from age 3 months to 4 years. In children from Beijing, TEWL values were higher in both arm locations than in children in Mumbai and Skillman. No significant differences were observed in TEWL or conductance between the white and African American groups.

Conclusion: In general, TEWL and conductance were greater on the upper inner arm than the dorsal forearm. Erythema and scaling were observed most often in subjects from Beijing and most infrequently in subjects from Mumbai. Stratum corneum water barrier properties were different in children and adults. Although there may be differences in these properties between ethnic groups in childhood, TEWL values were similar in adults across the three geographic locations and four ethnicities.

Figure 1

Transepidermal water loss (TEWL; mean ± standard error of the mean) decreased in children as a function of age at the (A) upper inner arm and (B) dorsal forearm, independent of region or ethnicity. For clarity, the age axis is shown as the log. *p < 0.05 versus adults from the same geographic region and ethnic group. Color of the asterisk indicates appropriate ethnic group comparison. No subjects from Beijing were recruited in the 37‐ to 48‐month age group.

Figure 2

Skin conductance (mean ± standard error of the mean) decreased in children as a function of age at the (A) upper inner arm and (B) dorsal forearm, independent of region or ethnicity. For clarity, the age axis is shown as the log. *p < 0.05 versus adults from the same geographic region and ethnic group. Color of the asterisk indicates appropriate ethnic group comparison. No subjects from Beijing were recruited in the 37‐ to 48‐month age group.

Figure 3

Representative facial images of infants and children from (left to right) Beijing, Mumbai, and Skillman (white, African American) under (A) visible light, (B) cross‐polarized visible light, and (C) ultraviolet excitation fluorescence mode. Cross‐polarized images revealed erythema on the faces of white and Beijing infants and adults, but not African Americans or those from Mumbai. Scaling was observed through ultraviolet imaging in infants and adults from Beijing and two infants from Mumbai. Glasses were used for the ultraviolet excitation fluorescence images to protect the eyes.

Figure 4

Percentage of subjects with (A) erythema and (B) scaling. No subjects from Mumbai exhibited erythema and no subjects from Skillman exhibited scaling. In Mumbai, only 2 of 30 (6.7%) infants ages 3 to 12 months showed evidence of scaling. No subjects from China were recruited in the 37‐ to 48‐month age group. W, white; AA, African American.