The field of inhalation toxicology is currently in an intriguing active
phase characterized by two features: (1) compilation, description and quantitation
of effects other than mortality that include physiological, morphological
and biochemical parameters, and (2) development of an understanding
of biologic responses in terms of the physical and chemical properties of inhaled
materials. Further development in both of these areas seems necessary
for inhalation toxicology to become a predictive discipline as opposed
to merely a descriptive one. The phenomena associated with deposition and
clearance of inhaled particles have recently been recognized as important
aspects of the defensive mechanisms of the lung. The purpose of this paper
is to justify the use of deposition and clearance tests in the inhalation toxicology
laboratory. AMRL-TR-75-125