Effect of various salt solutions on ultraviolet B-induced erythema and pigmentation

The combination of saltwater baths and subsequent ultraviolet irradiation is an effective treatment for psoriasis and atopic dermatitis. The aim of the present study was to determine the photosensitizing properties of two commercially available bath salts, original salt from the Dead Sea and sodium chloride. To address this issue, test areas on the volar aspects of the forearms were soaked with salt solutions for 15 minutes prior to ultraviolet-B (UVB) irradiation. The salt concentrations tested were 1%, 3% 5% and 15%. Tap water followed by UVB and UVB alone served as controls. Erythema was determined by visual and photometric measurement, and delayed tanning was assessed by colorimetry. Erythema obtained by wetting the skin prior to UVB irradiation was more pronounced than erythema induced by UVB alone. The most prominent erythema was yielded by tap water + UVB. The salts had a differing photosensitizing capacity and the strongest erythema was produced by the 5% solutions. There was only a moderate influence on delayed tanning by bathing the skin prior to irradiation. The results from the present study indicate that soaking the skin with salt solutions or tap water increases skin sensitivity to subsequent UVB irradiation. This may contribute to the effectiveness of salt water baths followed by UV irradiation and may account for an increased sunburn risk after bathing.