Persistence of Toluene Diisocyanate-Induced Asthma Despite Negligible Workplace Exposures: MATERIALS AND METHODS
A longitudinal study designed to assess the respiratory health risks associated with TDI involved 307 employees at two plants that produced polyurethane foam. In 1982, six of these workers were proven TDI-sensitive by inhalation challenge testing, using a protocol reported elsewhere. We reviewed the job histories of these six, and annually administered a respiratory questionnaire from 1982 to 1985. We determined work location within the plant and measured lung function and methacholine responsiveness yearly from 1982 to 1986. Personal TDI exposures also were measured during these years.
A modified Medical Research Council respiratory questionnaire was administered yearly to assess smoking habits and respiratory symptoms to describe: (1) lower respiratory symptoms—usual cough, usual wheeze, current attacks of dyspnea with wheeze or dyspnea while talking with other people; (2) upper respiratory symptoms—drip at the back of the nose or sinus trouble for at least three months; (3) chronic bronchitis—usual cough and phlegm for more than three months per year; and (4) dyspnea, grade 2 or higher—grade 2 = dyspnea while hurrying on level ground and grade 3 = dyspnea when walking with others ones own age. We also inquired about current medications at each yearly interview. canada drugs online
Pulmonary Function tests
Pre- and post-shift spirometry was performed using the Pulmolab model 5000 (Cardio-Pulmonaiy Instruments, Houston, TX) which includes a dry rolling-seal spirometer. An across-shift decline of 15 percent or greater in the FEV, was considered significant. At each testing session, subjects performed at least three satisfactory forced expiratory maneuvers, with the two largest FVC values within 5 percent of each other. From the two tests with the largest sum of FEV, and FVC, mean FEV, and FVC were expressed as percent predicted.