Effect of dietary administration of the rubber curative trithiocyanuric acid to the rat.

Trithiocyanuric acid (TCY) is a rubber curative of low oral and dermal toxicity and with a low potential for eye and skin irritation. This study determined the effects of TCY on Sprague-Dawley rats at levels of 0.0, 625, 2500 and 5000 ppm in the diet for 2-30 days. While there were some effects on body-weight gain and survival at the higher levels of intake, the main effects concerned unusual lesions of the pinna and the distal portions of the tail. Purplish discolorations of the ear margin and tip of the tail were noted in some animals on the 2500- and 5000-ppm diets. The tail lesion was evident microscopically at day 16 only in the 5000-ppm group and consisted of congestion of the vasculature in the subepidermal connective tissue with focal necrosis of the distal tail segment. By day 16 the ear lesion was also microscopically identifiable only in the group on the 5000-ppm diet. It was found in 33% of these animals at day 8 and in 67% at day 16 and consisted of a localized cellulitis characterized by moderate infiltrates of polymorphonuclear leucocytes in the epidermal and subepidermal tissues. The lesions caused by high levels of TCY were apparently site-specific, since histopathological examination of selected internal organs did not detect any lesions. The no-effect levels determined were 2500 ppm for microscopic lesions during an 8-16-day treatment period and 625 ppm for gross pathological lesions in a 30-day feeding study.