Cutaneous changes in rats induced by chronic skin exposure to ultraviolet radiation and organophosphate pesticide.

PURPOSE To study the possible potentiation of the carcinogenic effects of ultraviolet radiation associated with an organophosphate pesticide. METHODS Forty Wistar rats were assigned into four groups (n=10 each) randomized according to the procedures: group A received only UVR-B radiation; group B, UVR-B for eight weeks followed by a seven week period of pesticide exposure; group C, UVR-B + pesticide concomitantly: group D, only pesticide application. At the end of the fifth, tenth and fifteenth weeks the animals were photographed. Skin biopsy and histopathological study with Hematoxylin-Eosin were done on the fifteenth week. Statistical analysis with Fisher's and Sign (unilateral) tests, 5% value for significance. RESULTS Macroscopic lesions in the group A evolved from the erythema to erythema + desquamation. The groups B and C, with the association of two carcinogens, and group D presented evolution to keratosis, with higher incidence in group D. The histology showed a significant increase in the severity of injuries when the UVR-B and the pesticide were applied simultaneously, leading to cellular atypia. CONCLUSIONS Concurrent association of UVR-B to organophosphate pesticide produced more severe lesions microscopically, although this has not been so apparent macroscopically. In daily practice the clinical evaluation should be complemented with laboratory evaluation.