Acute and repeated dose inhalation toxicity of para-nitrophenol sodium salt in rats

Para-Nitrophenol Sodium Salt (PNSP) has relatively low acute inhalation toxicity; the 4-hr Approximate Lethal Concentration in rats is greater than 4.7 mg/l. One subacute study was conducted at 0, 0.34 and 2.47 mg PNSP/l for ten 6-hr exposures. Darker urine, proteinuria and elevated creatinine and SGOT were seen after exposure and were still evident after 14 days recovery. Methemoglobinemia also was seen and was reversible at 0.34 mg/l after 14 days. In addition, exposure to 2.47 mg/l caused elevated erythrocytes, hemoglobin and hematocrit. A second subacute study at 0.03 and 0.13 mg PNSP/l showed reversible methemoglobinemia only at 0.13 mg/l. The repeated dose no-observable effect level was 0.03 mg/l. No compound-related pathologic changes were noted in any of the studies.