Subchronic inhalation toxicity of 1,2,3-trimethylbenzene (hemimellitene) in rats.

Toxic effects of exposure to 1,2,3-trimethylbenzene (hemimellitene) in the condition of subchronic inhalation experiment were examined. Rats were exposed to vapours of hemimellitene at concentrations of 123 mg/m3, 492 mg/m3 and 1230 mg/m3, 6 h/day, 5 days/week for 3 months. After termination of a 3-month inhalation, animals were necropsied. Blood samples were obtained and selected organs were weighed and prepared for histological examinations. Subchronic inhalation exposure to hemimellitene resulted in an overall, low systemic toxicity. There were no changes in body weight gain and food consumption. At a concentration of 1230 mg/m3, the increase in relative liver weight was observed in male rats. It was accompanied by slight increase in sorbitol dehydrogenase activity. The increase in alkaline phosphatase activity was found in females only. Some disturbances in haematological parameters, characterised by the decrease in red blood cells and slight increase in white blood cells, segmented neutrophils and lymphocytes were observed in rats at high exposure concentration of 1230 mg/m3. The pulmonary lesions as well as the increased number of goblet cells and interstitial lung parenchyma infiltration were noted in male and female rats from the highest exposure groups.