They showed changes in airway responsiveness and airway inflammation in rats after challenge to an aerosol of endotoxin. Furthermore, a significant increase in secondary release of tumor necrosis factor, a proinflammatory marker, after endotoxin challenge was observed. This indicates that the airway inflammation caused by endotoxin exposure might be mediated through tumor necrosis factor release.
A significantly higher prevalence of most (chronic) respiratory symptoms was found in the exposed workers compared with control workers. Separate analysis of exposure categories revealed a concentration (present dust and endotoxin) dependent increase of shortness of breath prevalence. Cumulative dust exposure was a significant predictor of ever wheezing. Prevalence values were similar to those reported by Huy et al in grain workers and to animal dust-exposed nonsmokers.
Different symptoms correlated well with (individual) outcome of lung function measurements. Flovent inhalers other Chronic bronchitis was associated with a general decrease in all spirometric parameters whereas impedance parameters did not change significantly. Recently, Wesseling and Wout-ers reported normal impedance data in patients fulfilling the criteria of chronic bronchitis.
Possibilities for primary prevention of the observed effects include personal protection (mouthpieces) and an improvement of the ventilation. Secondary prevention might be improved by creating a health-hazard model that implements the dust-en-dotoxin ratio. Currently one facility is renovated with a new ventilation system. In the future, we plan to evaluate the respiratory consequences for the workers of this effort.
From the present study, the following can be concluded: (1) there is an apparent dose-related adverse respiratory effect of working in dust-exposed areas of animal feed facilities; (2) the dust in these facilities is contaminated with endotoxin and dose-response relationships indicate that the effect of endotoxin is more substantial than the effect of “dust;” and (3) impedance testing appeared to be more sensitive than spirometric testing with respect to detecting adverse respiratory effects of animal feed dust exposure.