Skin alterations induced by long-term exposure to uranium and their effect on permeability.

The skin is a probable route of incorporation of uranium by percutaneous absorption. The changes in epidermal thickness and their effect on skin permeability after uranium exposure are reported herein. Two experiments (A and B) were performed in Wistar rats weighing 60 g. In experiment A the animals were exposed to U3O8 (0.012 g d(-1)) in 30 daily topical applications. In experiment B the animals were treated as in experiment A, followed by a period of non-exposure of 60 d. Samples of the treated area of skin were taken for histologic studies and for the study of the skin permeability. The epidermal thickness was measured on the histological sections. Epidermis was thinner in experimental than in control animals in both experiments. The values in the control groups were 41.05 +/- 14.03 microm (A) and 38.92 +/- 16.50 microm (B) and 21.35 +/- 10.29 microm (A) and 24.06 +/- 16.50 microm (B) in the experimental groups, the differences being statistically significant. Skin permeability was measured placing skin samples in a diffusion cell, in which the upper compartment was filled with a staining solution. The determinations were made with a spectrophotometer. The results revealed that the skin permeability in both experimental groups was higher than in the respective controls, 65% in experiment A and 77% in experiment B. The results revealed that a long term uranium exposure leads to an epidermal atrophy which in turn results in an increased permeability of the skin.