Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the Golden Syrian hamster

Lethality, pathology, and various clinical chemical parameters were assessed in the hamster following a single ip or po treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). A single dose, 50-day LD₅₀ of greater than 3000 μg TCDD/kg, ip, was obtained for male and female hamsters while the LD₅₀ of orally administered TCDD was found to be 1157 μg/kg. Thus, the hamster appears to be the least sensitive mammalian species to the lethal effect of TCDD that has yet been investigated. TCDD treatment generally reduced the rate of body weight gain, with orally treated hamsters exhibiting the greatest reduction in rate. Thymic atrophy was the most consistent pathologic finding in TCDD treated hamsters. No histopathological changes were seen in the liver, spleen, kidneys, adrenals, or heart. Moderate to severe ileitis and peritonitis were found in many of the hamsters which died following oral treatment with TCDD. This lesion usually affects the distal ileum and consists of a marked hyperplasia of the mucosal epithelium with mild to severe hemorrhaging and necrosis. The intestinal lesion probably contributed in part to the greater lethality of TCDD in orally treated hamsters. A significant increase in serum alkaline phosphatase, bilirubin, protein, iron, cholesterol, and a decrease in serum albumin, chloride, urea nitrogen, and triglycerides were found in hamsters following both ip and po treatment with TCDD.