Lung Overload: A Challenge for Toxicology

Chronic lung overload may result in the development of fibrosis and of tumors in the lung parenchyma. The essential question that must be answered is whether there exists a threshold of exposure below which these effects are unlikely to occur. Both threshold and non-threshold mechanisms appear to exist for the two conditions, as illustrated by selected examples. Definition of a threshold is often driven by present analytical approaches. Mechanistic studies should not only address development of lesions, but also examine events that determine tissue recovery.