| Abstract: | Assessment of Toxicity of o-Nitrochlorobenzene in Rats followinga 4-Week Inhalation Exposure. NAIR, R.S., JOHANNSEN, F.R., LEVINSKAS,G.J., AND TERRILL, J.B. (1986). Fundam. Appl. Toxicol. 7, 609-614.o-Nitrochlorobenzene (ONCB) is a chemical intermediate usedfor the synthesis of various industrial chemicals. To evaluatethe subchronic toxicity of this compound, three groups of 15male and 15 female Sprague-Dawley rats were exposed to ONCBvapor 6 hr/day, 5 days/week for 4 weeks at target concentrationsof 10, 30, or 60 mg/m3. A control group of 15 animals/sex wasexposed to room air in a separate inhalation chamber. Concentrationsof ONCB in the chambers were determined at least three timesa day using a uv spectrophotometer. Parameters monitored inthis study included observation for signs of toxicity, bodyweights, ophthalmoscopic exam, hematology, and clinical chemistry.At necropsy, selected organ weights were recorded and over 35tissues/animal were examined microscopically for all controland high-exposure level animals. No mortality was observed inthis study. Mean body weights of all groups were comparableto controls. Animals exposed to the mid and high concentrationsof ONCB showed a significant increase in blood methemoglobinand a significant decrease in hemoglobin, hematocrit, and redblood cell counts. Spleen and liver weights (absolute and relativeto body weight) were significantly increased for these two groups.Microscopic changes, observed only in the spleen, included increaseddegree of extramedullary hematopoiesis and hemosiderosis. Thesedata suggest that the toxicity of ONCB is comparable to thatof its structural analog, p-nitrochlorobenzene. Thus these twocompounds should have similar workplace exposure limits. |
