Comparative clinical and electrometric assessments of the impact of surfactants on forearm skin.

Surfactant-based skin care products can induce minimal to more severe alterations to human stratum corneum (SC). These changes can be conveniently assessed using electrometric devices. Four different surfactant-based solutions were applied on the forearms of 10 healthy volunteers following a soap chamber test method. The 2-day patch testing was followed by a 2-week follow-up. Clinical and instrumental assessments were performed at 7 time points. Data generated by the Corneometer® CM820, the DermaLab Moisture Module® and the Nova Dermal Phase Meter (DPM)® 9003 were compared. The significant differences between the product aggressiveness to the SC were similarly disclosed by the Corneometer® and the DermaLab Moisture Module®. The ranking of product aggressiveness given by the 3 devices 5 days after patch removal was similar to that given by the clinical assessment of erythema. A high level of correlation were found between the values yielded by the immediate and continuous mode assessments using the DermaLab Moisture Module with the Pin Probe, while the correlation was weaker with the Nova DPM®.
This finding may be related to the fact that the Nova DPM is influenced by the accumulation of the transepidermal water loss in the continuous mode assessment while there is no significant occlusion effect of the DermaLab Moisture® Pin Probe that is more representative of the initial level of SC hydration. In conclusion, the Corneometer® and the DermaLab Moisture Module® respond similarly to changes in the SC content. This finding is different from some previous reports.