Pyranine, a fluorescent dye, detects subclinical injury to sodium lauryl sulfate
A. Pagnoni , A. M. Kligman , T. Stoudemayer

Synopsis

Anionic surfactants may damage the horny layer barrier in the absence of clinical signs of irritation. Increased permeability increases susceptibility to exogenous chemical insults.

We describe herein a rapid method for detecting invisible disruption of the barrier by sodium lauryl sulfate (SLS). Low concentrations of SLS, insufficient to induce visible changes, were applied occlusively in Hill Top chambers to the volar forearms of normal women for 24 hours. One hour after removal of the chambers, pyranine, a water-soluble fluorescent dye, was applied with a cotton-tip applicator and allowed to dry. The dye was gently washed off 30 minutes later. The intensity of the fluorescence was visualized under Wood's light immediately and 24 hours later. Ultraviolet photos were obtained for photographic documentation. Measurements of transepidermal water loss were made at the same time.

Concentrations of 0.025% and 0.1% SLS caused, in most of the subjects, no visible reactions. However, in comparison to a control water patch, both sites fluoresced strongly under Wood's light, more so with 0.1% SLS. Transepidermal water loss also increased, proportionally to concentration, validating barrier disruption. 0.005% SLS was below the threshold of injury by this methodology.

Pyranine fluorescence appears to be a useful technique for evaluating subclinical barrier damage from detergents.

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