Studies on dermal, ocular and respiratory effects of 4-ethyltoluene in experimental animals.

The toxicity of 4-ethyltoluene to experimental animals was studied after single and repeated exposures. It was found that 4-ethyltoluene can be classified as a very mild skin and eye irritant. Sensory respiratory irritation of 4-ethyltoluene was studied in Balb/C male mice using the plethysmographic method. The concentration at which the respiratory rate decreased to 50% (RD50 value) was determined to be 4216 mg/m3 (2795-5850 mg/m3 for 95% confidence interval). To study repeated-dose inhalation toxicity, male and female outbred Wistar rats were exposed in a dynamic inhalation chamber to 4-ethyltoluene vapours at concentrations of 477 or 2337 mg/m3, 6 h/day, 5 days/week for 4 weeks (20 exposure days). No significant changes were observed in food consumption and body weight gain. Statistically significant, concentration-dependent changes in the number of total cells, as well as of macrophages, polymorphonuclear leucocytes and lymphocytes were found in bronchoalveolar lavage. In the fluid of bronchoalveolar lavage, a significant, concentration-related increase was noted in total protein and mucoproteins and the activity of beta-glucuronidase, gamma-glutamyl transferase, lactate dehydrogenase and acid phosphatase. Histopathology revealed an increased rate of bronchitis and pneumonia and perivascular lymphoid infiltrations in rats exposed to 2337 mg/m3 of 4-ethyltoluene.