Organic dust exposure and respiratory health in the potato processing industry

Work-related respiratory health complaints were reported in a potato processing plant. Responsible agents and the underlying mechanism for these disorders were unclear. The first aim of this study was to quantify the occurrence of work-related respiratory health effects in workers of all four plants of the potato processing company. The second aim was to study three possible mechanisms: a Type I allergy to potato, a Type III allergy to microbial components or potato (Hypersensitivity Pneumonitis), and a non-specific airway inflammation caused by microbial components such as bacterial endotoxin.Sixteen percent of the 142 workers studied indicated work-related respiratory symptoms on a questionnaire. Specific IgE to airborne dust extract could not be detected in workers' sera, and therefore a Type I allergy was highly unlikely to play a role in the etiology of work-related respiratory effects. Specific IgG to airborne dust extract was detected in sera of nearly all workers. This humoral immune response was dominated by the IgG4 subclass, the latter being present in about half of the workers. The antigens involved appeared to be heat-labile potato proteins. No association was found between specific IgG and the prevalence of work-related respiratory symptoms.On the basis of these findings it was judged improbable that a Type III allergy and with that Hypersensitivity Pneumonitis played a predominant role in the etiology of work-related respiratory effects. High levels of airborne bacteria and endotoxin were found, being significantly related to acute lung function changes. This was observed both for spirometric lung function change across the Afternoon shift, and for peak flow changes across all three types of work shifts. Chronic respiratory effects were not observed in cross-sectional analyses, which might be partially due to a health-related selection in this industry.Results in this thesis strongly suggest a predominant role of non-specific airway inflammation caused by bacterial endotoxin in the etiology of acute respiratory effects. Recycling of process water contributes to bacterial growth and hence to the build-up of endotoxin. Control measures to reduce endotoxin exposure should be evaluated, with a priority for elimination and/or reduction at the source.