The respiratory tract is often the site of injury from occupational exposures. The widespread use of potentially toxic materials in the environment poses a major threat to both the airways and lung parenchyma. The respiratory tract has a limited number of ways to respond to injury. Acute responses include rhinosinusitis, laryngitis, upper airway obstruction, bronchitis, bronchoconstriction, alveolitis, and pulmonary edema. Chronic responses include asthma, bronchitis, bronchiolitis, parenchymal fibrosis, pleural fibrosis, and cancer. Early recognition and appropriate treatment of occupational lung diseases by physicians can reduce both morbidity and mortality significantly and greatly affect patient outcome. This chapter focuses on common occupational lung diseases and on how to diagnose and manage them.
The site of deposition of inhaled materials depends on water solubility for gases and particle size for solids (Table 23–1). Water-soluble gases and particles with a diameter in excess of 10 μm tend to get deposited in the upper airways, whereas insoluble gases and smaller particles penetrate to the lower airways. Subsequent respiratory injury depends on both the site of toxin deposition and the type of cell/structure damaged.
Table 23–1.Site of respiratory tract deposition and effect. |Favorite Table|Download (.pdf) Table 23–1. Site of respiratory tract deposition and effect.
|Water Solubility ||Examples ||Site of Injury |
|High ||Ammonia, formaldehyde ||Upper airway |
|Moderate ||Chlorine, sulfur dioxide ||Lower airways |
|Low ||Nitrogen oxides, phosgene ||Lung parenchyma |
|Particle Size (Aerodynamic Diameter) |
|>10 μm ||Dust from Earth's crust ||Upper airway |
|2.5–6 μm ||Some fire smoke particles ||Lower airways |
|<2.5 μm ||Metal fumes, asbestos fibers ||Lung parenchyma |
EVALUATION OF PATIENTS WITH OCCUPATIONAL LUNG DISEASE
A careful evaluation can identify and diagnose occupational lung disease successfully in most cases. The following four approaches are recommended: (1) detailed history, including occupational and environmental exposures, (2) thorough physical examination, (3) appropriate imaging studies, and (4) pulmonary function testing.
A detailed history of both the patient's complaints and environmental/occupational exposures is essential. Work practices should be explored extensively with attention to types and durations of exposures, whether appropriate environmental controls are present, and if respiratory protective gear is used. If available, substance data sheets (SDSs) should be reviewed. These documents profile the important health, safety, and toxicologic properties of the product's ingredients and under federal law must be furnished by the employer to the worker or to the worker's health care provider on request.
If available, actual industrial hygiene data on the level of exposure and the agent to which the patient was exposed should be obtained. The history should include the condition of the patient's home, any hobbies, and social habits because exposures outside the workplace that contribute to or cause the lung injury may be discovered.
Occupational lung diseases do not present with specific clinical findings. It is difficult, ...