Comparison and correlation between stinging responses to lactic acid and bioengineering parameters

Abstract

In evaluating the safety of a novel cosmetic product or a new chemical, it is important to assess susceptible population. One group of subjects is known to stingers who are more likely to experience sensory effects such as stinging and burning after contacting with cosmetics. The purpose of the study is to measure skin biophysical parameters noninvasively in stingers and non-stingers and to see their correlations with stinging responses. 298 women were evaluated by modified lactic acid stinging test with 5% lactic acid solution rather than classic 10% solution because of strong reaction in Asian populations. Transepidermal water loss (TEWL), skin hydration, sebum content, and pH were measured using the bioengineering instruments in an environment-controlled room. Correlations between stinging responses and skin biophysical parameters were statistically analysed. There was a positive correlation between stinging responses and TEWL evaluation. However, no correlations was observed between stinging responses and other parameters such as skin hydration, sebum content, and pH. Our data indicate that there is a relationship between the degree of stinging and the skin barrier function. However, we believe that various additional studies are necessary to characterize skin of stingers and the pathogenesis.

What Is Sensitive Skin? A Systematic Literature Review of Objective Measurements

“…A lower CAP at baseline predicted earlier onset of stinging and a weak correlation (Spearman's test: r = 0.307, p = 0.03), with a higher clinical stinging score identified [39]. On the other hand, other studies found no difference in CAP between stingers and nonstingers [40,50,51] or between subjects with sensitive and nonsensitive skin [20,48], either challenged or unchallenged [20,48,51]. The lower CAP is consistent with findings of a clinically dryer skin [15] and a lower facial ceramide content of the stratum corneum found in subjects with sensitive skin (p = 0.037) [38].…”

“…Overall, 10 studies presented data on hydration of the stratum corneum (measured through capacitance, CAP) in sensitive skin (table 1). A significantly lower CAP at facial areas in subjects with sensitive skin [37] and in stingers [40] and a nonsignificantly lower CAP at facial areas in subjects with sensitive skin were found [41]. Challenging the skin with octane or cumene, however, resulted in a significantly lower CAP in stingers compared to nonstingers [51].…”

“…Most studies observed higher TEWL in the unchallenged skin of subjects with sensitive skin compared to those with nonsensitive skin [20,41,48,49] and in stingers compared to nonstingers [39,40,41,50,51], while only 2 studies identified significantly higher TEWL in sensitive skin [40,41]. Moreover, higher TEWL at baseline seems to correlate with a stronger TEWL increase following provocation [40]: plastic occlusion resulted in a significantly longer evaporation half-life time in subjects with sensitive skin [49], and a trend to increased recovery time of TEWL following SLS stimulation was also observed [20]. A stronger increase of TEWL was also found following SLS provocation both in sensitive versus nonsensitive atopic skin [52] and in a population of Japanese versus German women [53].…”

“…In studies evaluated in this review, clinically less oily (p < 0.01) skin was detected in subjects with sensitive skin [37]. However, objective surface sebum measurements show no differences between subjects with sensitive and nonsensitive skin [37,54] and between stingers and nonstingers [40]. It is remarkable that Asian people, who more often report sensitive skin [53,55], have a clinically more oily skin compared to Caucasians (31.9 vs. 24.0%).…”

“…Only 2 studies using the LAST as an indicator of sensitive skin found significant differences in biophysical measurements in stingers, namely, a higher transepidermal water loss (TEWL) on the nasolabial fold (p = 0.03) and on the right (p = 0.05) and left cheek (p = 0.03) [40,41]. Important to note here is that Distante et al [41] (2002) included subjects who also met the criteria of self-reported sensitive skin and who had specific skin reactions besides a positive LAST.…”