Weissman D; Wagner GR
Preventing occupational disease and injury, second edition. Levy BS, Wagner GR, Rest KM, Weeks JL, eds. Washington, DC: American Public Health Association, 2005 Jan; :444-448
Silicosis is an intersitial lung disease caused by inhalation of free crystalline silica (silicon dioxide). The surveillance case definition used by the Sentinel Even Notification System for Occuapational Risks (SENSOR) program of NIOSH requires exposure to silica and x-ray or pathological changes consistent with silicosis. Clinically, the diagnosis of silicosis is based on history of inhalation exposure, presence of opacities on chest x-ray that are consistent with the diagnosis, and exclusion of other possible diagnoses. Silicosis is associated with several patterns of chest x-ray abnormality. Simple silicosis is a profusion of small (<10 mm in diameter) opacities. These are generally rounded, but may be irregular, and occur predominantly in the upper lung zones. Conglomerate silicosis or progressive massive fibrosis (PMF) occurs when these small opacities enlarge and coalesce to form larger, upper or mid-zone opacities (>10 mm in diameter). The chest x-ray in acute silicosis, described below, is characterized by lower-zone alveolar filling and resembles conditions such as pneumonia or alveolar proteinosis. Silicosis can be clinically and temporally classified into several different patterns. Chronic silicosis develops slowly, usually appearing 10 to 30 years after first exposure. It may be identified many years after leaving the job associated with exposure. The chest x-ray of most people with chronic silicosis shows diffuse nodular changes, but in a minority of people with chronic silicosis, nodules coalesce to become PMF. Accelerated silicosis develops less than 10 years after first exposure. It has the same radiographic appearance as chronic silicosis and is differentiated only by its more rapid development. Acute silicosis results from overwhelming exposure to fine respirable particles of crystalline silica over a short time, typically less than several years. The exposure results in symptoms within a few weeks to 4 or 5 years after the initial exposure.
Silicosis; Lung-disease; Silica-dusts; Silicates; X-ray-analysis; Inhalation-studies; Exposure-levels; Chest-X-rays; Pulmonary-system-disorders; Respiratory-system-disorders; Exposure-assessment; Occupational-exposure; Radiographic-analysis; Respirable-dust
Levy BS; Wagner GR; Rest KM; Weeks JL
HELD; DRDS; OD
Preventing occupational disease and injury, second edition