Objectives To determine the risk of German compost workers developing chronic respiratory effects from long-term exposure to bioaerosols.
Methods Respiratory health was determined in 74 currently exposed compost workers and 37 non-exposed controls after 13 years of follow-up. In addition, 42 former compost workers (drop-outs) who left their work during the follow-up period were also examined. Respiratory symptoms and working conditions were assessed using identical questionnaires as at baseline. In addition, lung function was measured using the same spirometer as in the initial study. Sera from both surveys were tested for specific IgE and IgG antibodies to moulds and the risk of work-related symptoms was evaluated using regression approaches for prospective studies with binary data.
Results In the follow-up period, the number of participants reporting cough significantly increased in compost workers and drop-outs compared to the controls. Working as a compost worker for at least 5 years increased the relative risk for cough (RR 1.28; 95% CI 1.2 to 1.4) and for cough with phlegm (RR 1.32; 95% CI 1.2 to 1.5). Current and former compost workers had slightly lower predicted percentage of forced expiratory volume in 1 s and predicted percentage of forced vital capacity than controls, but decrease in lung function during follow-up was not different among the 3 groups. In addition, no significant changes could be detected in antibody concentrations.
Conclusions Our results suggest that chronic exposure to bioaerosols in composting plants is related to a significantly higher risk for cough with phlegm, indicating chronic bronchitis. However, compost workers showed no higher incidence of deterioration of pulmonary function over the study.
- Bioaerosol exposure
- Compost workers
- Respiratory health
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Contributors VvK, AD, MR and JB contributed to the conception and design of the study with advice from HDN, EW, CF and RS. VvK, FH, AD, MB, EW and JB were involved in data collection. BK and SC provided statistical expertise. VvK prepared the first draft of the manuscript, and FH, BK, SC, TB, MR and JB critically revised the manuscript. All authors approved the final manuscript.
Funding The study was funded by the grant F 2063 from the Federal Institute for Occupational Safety and Health (BAuA) and by the German Social Accident Insurance (DGUV, IPA-94).
Competing interests MR has received lecture honoraria from Astellas Pharma GmbH, ThermoFisher Scientific and HAL Allergy.
Patient consent Obtained.
Ethics approval Ethics committee of the Ruhr-University Bochum.
Provenance and peer review Not commissioned; externally peer reviewed.
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