Skin damage in adult amphibians after chronic exposure to ultraviolet radiation.

The effects of repeated UV exposure on the skin of the European crested newt, Triturus cristatus carnifex, have been investigated. The animals were irradiated 3 times per week with a Westinghouse FS40T12 fluorescent sun lamp (wavelength spectrum 275-350 nm). Two groups of animals received the same total fluence of 1.3 x 10(5) J/m(2) in single fluences of either 1570 J/m(2) (group A) or 9430 J/m(2) (group C), and one group received a total fluence of 2.6 x 10(5) J/m(2) in single fluences of 4710 J/m(2) (group B). All the animals were killed in 7 months after the first UV exposure, but at different intervals after the last exposure. Striking epidermal hyperplasia was found in the newts irradiated at the lower fluence rate group (group A). In the animals given the higher total fluence (group B), the most prominent skin changes were dermal fibrosis and irregular thinning and thickening of the epidermis. No significant skin changes were found in group C, in which if there had been UV lesions, they had been repaired during the 5 month interval between the last irradiation and the killing of the animals. No skin tumors developed in any experimental group.