Toxic risks from inhalation of bacterial endotoxin.

A potential risk for workers exposed to inhalation of endotoxin, as well as the primary tissue changes, is the possibility of subsequent development of adult respiratory distress syndrome. Accordingly, hamsters were administered one hour aerosols of Enterobacter agglomerans and allowed to rest for six hours to produce maximum microlesions in the lung. One hour before this peak, the animals were injected intravascularly with the same suspension used in the aerosol. After one hour the animals were killed and bronchopulmonary lavages were made for analysis of free lung cells. As anaesthesia alone has been reported to be one of the operative procedures that enhance the effect of previous exposure to endotoxin, controls had to include sham anaesthesia with no intravascular injection. Endotoxin inhalation induced significant increases in total number of pulmonary leucocytes, mostly neutrophils, but with a concomitant relative decrease in number of alveolar macrophages. These polymorphonuclear neutrophils are not seen in morphometric analysis of the alveoli. Of greater interest was the large increase in erythrocytes suggesting pulmonary haemorrhages. Such changes were not due to intravenous bacterial alone, and were only significant when the bacteria were inhaled. Taken together with the other known inflammatory effects of inhaled bacteria or bacteria containing endotoxin, such inhalation in an occupational setting constitutes an increasingly recognised risk for workers.