Effects of cemented tungsten carbide dust on rat lungs following intratracheal injection of saline suspension.

In order to examine the effect of cemented tungsten carbide dust on the animal lung, saline suspensions were intratracheally administered into the lungs of rats in a single dosage. About one-fifth of the animals died during the first three days. The acute response of the lungs was hemorrhagic edema with intense alveolar congestion. The animals killed at six months all presented pulmonary lesions of patchy fibrosis in the vicinity of the deposited dusts, occasionally associated with focal traction emphysema and bronchobronchiolar ectasia. At twelve months, two-third of the animals had neither fibrosis nor dust deposition, although the remaining animals showed pulmonary lesions similar to those seen in the six-months responders. Fibrosis of the lungs seemed to consist of collapsed alveoli with condensation of the preexistent reticulin fibers, but without noticeable collagenization. It is supposed that both the early toxic and the late fibrogenic effects of the carbide dust are attributable to the cytotoxic action of cobalt present in the dust particles. It is possible that recovery of the pulmonary lesions results from removal of the dusts from the lesions.