A comparison of the effect of UVB and sodium lauryl sulphate on skin water vapour loss.

The effect of erythemogenic UVB irradiation and minimal erythemogenic concentration of sodium lauryl sulphate(SLS) 4% aqueous (a skin irritant) irritation, on skin water vapour loss (SVL) of 12 male Chinese volunteers was studied. The mean SVL rate of unirradiated/unirritated skin was 4.5(+/- 2.0) g water/m2/h. The mean rate for UVB irradiated skin was 6.2(+/- 3.9) g water/m2/h and the rate for SLS irritated skin was 38.5(+/ 22.3) g water/m2/h (p = 0.0003). The irritation index (defined as SVL rate of irradiated or irritated minus that of unirradiated/unirritated skin divided by SVL rate of unirradiated/unirritated skin) was significantly lower on UVB irradiated skin (0.4 +/- 0.5) than SLS irritated skin (8.1 +/- 4.2) (p = 0.0001). It appears that UVB irradiation has significant less effect on the skin barrier compared with SLS irritation. It appears that SVL measurement may be used to differentiate UVB induced erythema from irritant induced erythema.