© 1987 Oxford University Press
research-article |
Diesel Exhaust Is a Pulmonary Carcinogen in Rats Exposed Chronically by Inhalation
Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute P.O Box 5890, Albuquerque. New Mexico 87185
Diesel Exhaust Is a Pulmonary Carcinogen in Rats Exposed Chronically by Inhalation. MAUDERLY, J. L., JONES, R. K., GRIFFITH, W. C., HENDERSON, R. F., AND MCCLELLAN, R. O. (1987). Fundam. Appl. Toxicol 9, 208–221. Male and female F344 rats were exposed 7 hr/day, 5 day/week for up to 30 months to automotive diesel engine exhaust at soot concentrations of 0.35, 3.5, or 7.0 mg/m3 or were sham-exposed to clean air. Rats were terminated at 6-month intervals to measure lung burdens of diesel soot and for histopathology. Other rats either died or were terminated after 30 months of exposure. Lungs were fixed, sectioned into 3-mm slices, and examined by a dissecting microscope to detect tumors. Lesions were stained and examined by light microscopy. Survival and body weight were unaffected by exposure. Focal fibrotic and proliferative lung disease accompanied a progressive accumulation of soot in the lung. The prevalence of lung tumors was significantly increased at the high (13%) and medium (4%) dose levels above the control prevalence (1%). Four tumor types, all of epithelial origin, were observed: adenoma. adenocarcinoma, squamous cyst, and squamous cell carcinoma. Logistic regression modeling demonstrated a significant relationship between tumor prevalence and both exposure concentration and soot lung burden. These results demonstrate that diesel exhaust, inhaled chronically at a high concentration, is a pulmonary carcinogen in the rat.