Impedance measurements were always performed prior to registration of flow volume curves to avoid the influence of forced expiratory maneuvers on the bronchial tone. All subjects were measured at least 4 h after beginning their shift since acute respiratory effects of endotoxin exposure are measurable 4 h after exposure. Lung function measurements were obtained from 205 male workers: 60 office staff (group l=not exposed), 145 blue collar workers (group 2=exposed). Since three spirometric measurements and three impedance measurements failed due to technical problems and the previously mentioned maintenance personnel (n=5) were excluded, eventually 194 workers were considered in this study (Table 1).
Occupational category means were used to estimate the present inspirable dust and endotoxin exposure (Table 2). Present exposure levels were ranked according to Huy et al in four exposure categories: not exposed, 0 to 4 mg/m; 4 to 9 mg/m; and >9 mg/m, representing arithmetic means (AM). Effects of present exposure on lung function were analyzed by regression analysis with age, height, pack-years, and years after smoking cessation as predictor variables. Weight was included as predictor variable because overweight status is associated with increased total respiratory resistance and decreased total respiratory reactance purchase zyrtec. The results were expressed as adjusted mean values (SEM). Each subject’s individual (cumulative) dose of total grain dust and of endotoxin exposure was derived from his personal job history. The product of the occupational category mean (AM) and the number of years employed with that job title was computed for every job that was reported by the worker. Cumulative exposure was computed for each worker by adding the results for all jobs held. Long-term effects of grain dust and endotoxin on flow volume and impedance parameters were tested by multiple linear regression. In this linear regression, lung function parameters were taken as dependent variables and the confounders (age, height, weight, smoking) and (cumulative) exposure as the independent variables. First the confounders and subsequently the cumulative exposure were put into the model of linear regression. Correlation between respiratory symptoms and lung function parameters was tested by multiple logistic regression (BMDP, Berkeley, Calif).
Table 2—Mean Dust (mg/ms) and Endotoxin (ng/m3) Concentrations by Job Category (n=54 Samples)
|Job Category||Airborne Dust, mg/m||Endotoxin, ng/m|
|“Jacks of all trades”||36.1||4.4||(0.7-199.2)||29.1||5.8||(0.3-317.2)|