The influence of low concentrations of irritants on skin barrier function as determined by water vapour loss.

The effect of some irritants on the barrier function of the skin was assessed by means of water vapour loss measurements. 100 microliter of the test substance in distilled water were applied to the skin for a period of 48 h, using large Finn chambers. The exposures were done in a test panel of 42 subjects. Sodium lauryl sulfate (2%), cocobetaine (2%), crotonaldehyde (0.75%) with sodium lauryl sulfate (0.5%) and dimethyl sulfoxide (50%) markedly influenced water vapour loss. Sodium hydroxide (1%) had less effect on water vapour loss, although the increase was significant (p less than 0.05). Phenol (5%) and benzalkonium chloride (0.2%) did not significantly influence the loss of water through the skin. It is concluded that subclinical effects of chemicals on the barrier function may be of importance in the development of irritant contact dermatitis, but that this capacity is probably not the only factor which determines the potential of a substance to contribute to the development of irritant contact dermatitis. A chemical which has little or no effect on the function of the horny layer may have a toxic effect on the viable cells of deeper layers of the skin. This toxic effect may also be an important subclinical factor in the development of irritant contact dermatitis.