Workers exposed to dust from vegetable fibers such as cotton, flax, and hemp have long been recognized to have respiratory symptoms such as chronic bronchitis and acute chest tightness at work add comment canadian drug mall. The term byssinosis was first used in the late 19th century to describe a symptom complex that occurs with predictable periodicity, ie, chest tightness occurring at work on the first day of the work week initially and then on other days in more advanced stages. The syndrome occurs with variable latency (years, usually) after first exposure. The chest tightness may be accompanied by shortness of breath, cough, and wheezing. Since the clinical presentation often is imprecise, with nonspecific symptoms occurring in a specific time pattern, byssinosis can be easily overlooked clinically. In earlier studies of byssinosis, ventilatory tests were not used.
Later, Schilling et al and others included spirometric testing before and after the work shift in an attempt to better characterize the syndrome. These investigations revealed that acute across-shift airway obstruction occurred in some, but not all, workers with the symptoms of byssinosis. Investigation of workers in ten cotton mills in the United Kingdom showed that almost all of the symptomatic workers were exposed to dust levels above 1 mg/m, while later studies in the United States revealed respiratory symptoms at levels considerably lower than this, and a standard of 0.2 mg/m was adopted in the United States.
Current studies of the possible link between acute symptoms of byssinosis and excess respiratory morbidity and mortality in textile workers build on the early observations of Schilling et al. Research questions asked 30 years ago about the relationship between acute symptoms or across-shift change in lung function and chronic, permanent respiratory impairment remain largely unanswered. Interestingly, cross-sectional epidemiologic studies have shown that an across-shift decline in lung function does not correlate well with byssinosis symptoms. For instance, only 5 to 25 percent of workers with byssinosis will have significant across-shift changes when examined cross-sectionally. Conversely, only 5 to 15 percent of those with across-shift changes report the byssinosis symptom complex.