BACKGROUND:
The two projects were part of a Specialized Center of Research (SCOR) in Occupational and Immunologic Lung Disease. Since its inception in 1972, researchers in the SCOR have conducted epidemiologic studies on asbestosis, silicosis in sandblasters, and respiratory reactions in workers exposed to detergent enzymes and polyvinyl chloride film fumes.
Irritant gases and vapors are utilized in herbicides, pesticides, pharmaceuticals, household cleaners, explosives, fertilizers, refrigeration, plastics, paints, fumigants and a variety of other products. These chemicals are produced and used immediately or shipped to end-users. The potential for chemical accidents is great. A report for the Environmental Protection Agency estimated that 6,928 chemical accidents have occurred in the United States since 1980, an average of five accidents each day. As a result, 1,500 people were injured and 135 killed. More information was needed on the consequences of chemically-induced sublethal acute lung injury and on the long term outcome of chemical vapor/gas specific injury in order to differentially treat exposure to these chemicals.
Byssinosis has been recognized as a respiratory disorder associated with cotton dust exposure for more than two centuries. This respiratory disorder is characterized by the clinical symptoms of bronchoconstriction with work week periodicity and later by a decline in lung function over the working shift, most marked following an absence from the job. Byssinosis risk is probably influenced by length of exposure and type of mill such as textile mill, cottonseed oil crushing mill, or ginning mill. Prevalence seems not to be influenced by age, sex, or race. This study attempted to answer the question whether long-term exposure to cotton textile dust led to clinically important pulmonary functional impairment.
DESIGN NARRATIVE:
Respiratory Effects of Exposures to Irritant Gases and Vapors:
Workers filled out respiratory questionnaires and underwent spirometry tests at their plants at baseline with follow-up every one to two years over a five-year period. Initial total IgE was measured in a 20 percent sample to determine its ability to detect longitudinal changes in lung function and whether it mediated immunoreactivity. In workers exposed to chemical spills, a determination was made if short-term, high level chemical exposure without lung injury or short-term, high level chemical exposure with lung injury affects lung function longitudinally or affects the acquisition of respiratory symptoms. In injured workers and a matched control group, spirometry was performed immediately, at two weeks, at six weeks, and at one year after the episode. In the week after an acute injury, circulating biochemical indications of cell and tissue injury were measured. Total and specified IgE were measured after injury and compared to baseline measurements.
The longitudinal study had two components. In the first, the Tulane SCOR investigators collected pulmonary function, respiratory health, immunologic, and industrial hygiene data on 300 workers in nine textile plants (six cotton and three synthetic) for comparison with the company's data. In the second component, Tulane investigators worked closely with the participating company to insure the quality of data the company collected in their respiratory health surveillance program on workers in the nine plants.
Data were collected on sex, race, smoking, age, atopic status, degree of bronchoconstriction in response to cotton dust exposure as measured by Monday shift change in FEV1, length of employment, past and current exposure to cotton dust, job type, grade of cotton processed, geographical location of the plant, and bacterial contamination of the cotton. Lung function tests were conducted annually for five years by obtaining pre- and post-shift spirometric data. Data were available on the company's dust measurements for the past ten years. Dust measurements were made during the study to reconstruct a complete exposure profile for the various job titles in each production area during the total period of employment of workers participating in the study. |
