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By Lee S. Newman, MD, MA, Professor, Departments of Environmental and Occupational Health and Epidemiology;Professor of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, Colorado School of Public Health;Colorado University Anschutz

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Byssinosis is a form of reactive airways disease characterized by bronchoconstriction in cotton, flax, and hemp workers. The etiologic agent is bacterial endotoxin in cotton dust. Symptoms are chest tightness and dyspnea that worsen on the first day of the work week and subside as the week progresses. Diagnosis is based on history and pulmonary function test findings. Treatment includes avoidance of exposure and use of asthma drugs.


Byssinosis occurs almost entirely in workers who contact unprocessed, raw cotton, especially those who are exposed to open bales or who work in cotton spinning or in the carding room. Byssinosis can occur after acute exposure but usually occurs in workers with a history of chronic exposure. Evidence suggests that the cause is bacterial endotoxin in the cotton dust. The endotoxin leads to bronchoconstriction, chronic bronchitis, and gradual decreases in pulmonary function, particularly in genetically susceptible people. Prolonged exposure to cotton dust was once thought to cause emphysema, a theory now disproved.

Symptoms and Signs

Symptoms are chest tightness and dyspnea that lessen with repeated exposure. Symptoms develop on the first day of work after a weekend or vacation and diminish or disappear by the end of the week. With repeated exposure over a period of years, chest tightness tends to return and persist through midweek and occasionally to the end of the week or as long as the person continues to work. This typical temporal pattern distinguishes byssinosis from asthma.

Signs of acute exposure are tachypnea and wheezing. Patients with more chronic exposure may have crackles.


Diagnosis is based on history and pulmonary function tests that show typical airflow obstruction and a reduction in ventilatory capacity, especially if measured at the start and end of a first work shift. Hyperresponsiveness to methacholine is also often observed. Surveillance measures, including symptom reporting and spirometry in textile workers, can aid in early detection.


Treatment includes avoidance or reduction of exposure and use of asthma drugs.