2,3,7,8-Tetrachlorodibenzo-p-dioxin: Acute oral toxicity in hamsters

The acute oral toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was evaluated in hamsters. Male golden Syrian hamsters received 0 (corn oil only), 300, 600, 1000, 3000, or 6000 μg TCDD/kg body wt by single-dose gavage. To facilitate dosage, TCDD was fed as a suspension in acetone/corn oil (1:9). The 55-day single-dose oral LD50 was 5051 μg/kg (3876–18,487 μg/kg, 95% confidence interval). Deaths occurred from Day 9 through Day 43 following single-dose administration. Initially, no hamsters exhibited adverse effects related to dosage with TCDD, but 4–5 weeks following dosage, hamsters of the 1000, 3000, and 6000 μg/kg dose groups began to develop unkempt hair coats. A dose-related depression of mean body weight when compared to control weights was apparent in hamsters of the 1000, 3000, and 6000 μg/kg dose groups by 3 weeks posttreatment. Gross necropsy revealed the primary target organs affected in the hamster to be the same as in other laboratory species, namely, liver and thymus; this was accompanied by a slight decrease in adipose tissue reserves. No other significant effects were noted upon necropsy. Based on these results, the hamster appears to be much less sensitive than other laboratory species to the acute oral toxicity of TCDD.