PRINCIPLES OF TOXICOLOGY

9 Pulmonotoxicity: Toxic Effects in the
Lung
PULMONOTOXICITY: TOXIC EFFECTS IN THE LUNG
CHAM E. DALLAS
In this chapter the anatomy and physiology of the lung will be related to the most prevalent mechanisms
of lung toxicity resulting from exposure to commonly encountered industrial toxins. Specifically, the
chapter will discuss
• Lung anatomy and physiology
• Defense mechanisms of the lung
• Different classes of chemicals that are known to damage the lung
• Four basic mechanisms by which industrial chemicals exert toxic effects on the lung
• Clinical evaluation of occupational lung injuries
When considering toxicology and the lung, it is important to note that the lung is both a target organ
for many toxins and a major port of entry into the body, providing toxins the opportunity to exert toxic
effects in other organs.
9.1 LUNG ANATOMY AND PHYSIOLOGY
The lung and the rest of the respiratory system provide all the cells in the body with the ability to
exchange oxygen and carbon dioxide. The same system can also provide many industrial toxins with
entry to (and in some cases exit from) the body. Essentially, the respiratory system is an air pump, just
as the heart is a blood pump for the circulatory system. Changes in the anatomy and physiology of the
lung due to toxin exposure can often result in very severe health consequences for the exposed
individual. An understanding of the structure and function of the respiratory tract is essential to
understanding why so many individuals in occupational exposures suffer these toxicologic outcomes.
Upper Airway
The entry-level area into the respiratory system is known as the nasopharyngeal region. The upper
airway is generally considered to extend from the nose down to approximately the area of the vocal
cords. Air that is inhaled into the nose enters the nasal openings and goes initially upward, then takes
an abrupt turn and goes downward into the throat. Of course, humans can also choose to breathe through
the mouth, in which the nasopharyngeal portion of the “respiratory tree” is bypassed. In most instances,
mouth breathing entails a calculated effort on the part of the individual and has been observed when
the nasal pathway is blocked or obstructed and when the individual needs to dramatically increase the
volume of breathing.
Principles of Toxicology: Environmental and Industrial Applications, Second Edition, Edited by Phillip L. Williams,
Robert C. James, and Stephen M. Roberts.
ISBN 0-471-29321-0 © 2000 John Wiley & Sons, Inc.
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