Determinants of microbial exposure in grain farming.

OBJECTIVES: Exposure to organic dust containing high concentrations of microorganisms is common in grain farming, although the farmers have practices to counteract microbial growth to obtain optimal grain yields. We investigated the influence of weather and production practices on personal microbial exposure during grain work. METHODS: Airborne dust was collected by personal sampling during threshing and storage work on 92 Norwegian farms. The personal exposure for bacteria, endotoxin, fungal spores and hyphae, beta-(1-->3)-glucans and actinomycetes was quantified and compared with climatic data expressed as fungal forecasts from the grain growth season and production practices as reported by farmers. RESULTS: Farmers were exposed to a geometrical mean of 4.4 mg m(-3) inhalable dust [geometrical standard deviation (GSD) = 4.0], 4 x 10(6) m(-3) bacteria and fungal spores (GSD = 5.2 and 5.9, respectively), 5.9 x 10(3) EU m(-3) of endotoxins (GSD = 8.6), 2 x 10(5) m(-3) actinomycetes (GSD = 15.3), 120 mug m(-3) beta-(1-->3)-glucans (GSD = 4.7) and 5 x 10(5) AU m(-3) of hyphae (GSD = 4.4). Univariate associations were found between one or several of these microbial factors and work operation, visible fungal damage, grain species, lodging of grain, storage technology or harvester type. As assessed by general linear models, storage work was the main predictive determinant for microbial exposure, although grain species and visible fungal damage also were also important. Wet and warm weather throughout the grain growth season were associated with elevated exposure for inhalable dust, beta-(1-->3)-glucans, endotoxins and hyphae during threshing. The beta-(1-->3)-glucan exposure could biologically be explained by the fungal spore and hyphal exposure, both variables contributing equally. However, spores were most important during storage work, whereas only hyphae were predictive during threshing. CONCLUSIONS: Farmers were exposed to high levels of microorganisms and their components during dusty grain work. Dust prevention and protection may reduce microbial exposure, and may be particularly important in areas with frequent fungal forecasts, when fungal damage has been observed, during storage work or when handling barley.

Airway inflammation in waste handlers exposed to bioaerosols assessed by induced sputum.

Work-associated lower airway inflammation in waste collectors was examined by induced sputum and correlated with the bioaerosol exposure. Organic waste collectors (n=25) underwent induced sputum collection and spirometry before work on Monday and the following Thursday. Total cells, cell differentials, interleukin (IL)-8 and eosinophilic cationic protein were determined. Personal full-shift exposure measurements were performed Monday, Tuesday and Wednesday and analysed for total bacteria, fungal spores, endotoxins and beta(1-3)-glucans. The percentage of neutrophils (46-58%) and the IL-8 concentration (1.1-1.4 ng x mL(-1)) increased from Monday to Thursday. Forced expiratory volume in one second (FEV1) was significantly reduced on Thursday, and the decrease in FEV1/forced vital capacity correlated with the increase in the percentage of neutrophils. The median exposure to endotoxin (range 7-180 EU x m(-3)) and beta(1-3)-glucan (range 5-220 ng x m(-3)) was correlated with the increase in IL-8. Bioaerosol exposure during waste collection induced an inflammatory response in the lower airways, characterised by neutrophils and interleukin-8 secretion, that influenced the lung function. The inflammatory response was related to microbial components in the bioaerosol and was more pronounced for endotoxin than beta(1-3)-glucan exposure. No associations were found for mould spores or bacteria.

Upper airway inflammation in waste handlers exposed to bioaerosols.

AIMS: To examine work associated upper airway inflammation in 31 waste handlers, and to correlate these findings with personally monitored exposure to different bioaerosol components. METHODS: Cell differentials, interleukin 8 (IL-8), myeloperoxidase (MPO), and eosinophilic cationic protein (ECP) were examined in NAL (nasal lavage), and swelling of the nasal mucosa was determined by acoustic rhinometry before work start on Monday and the following Thursday. Bioaerosol exposure was determined by personal full shift exposure measurements on Monday, Tuesday, and Wednesday and analysed for total bacteria, fungal spores, endotoxin, and beta(1-->3)-glucans. RESULTS: The increased percentage of neutrophils from Monday (28%) to Thursday (46%) correlated with increases in ECP (r(S) = 0.71, p < 0.001) and MPO (r(S) = 0.38, p < 0.05), and showed a close to significant correlation with nasal swelling (r(S) = -0.55, p = 0.07). The Thursday levels of neutrophils, MPO, and IL-8 were associated with the exposure to fungal spores (range 0-2.0 x 10(6)/m(3)) and endotoxin (range 4-183 EU/m(3)) measured the day before, and the median exposure to beta(1-->3)-glucans (range 3-217 ng/m(3)), respectively (r(S) = 0.47-0.54, p < 0.01). Swelling of the nasal mucosa was associated with the fungal spore and beta(1-->3)-glucan exposure (r(S) = 0.58-0.59, p < 0.05). CONCLUSION: These results are based on a relatively small population, and conclusions must be drawn with care. The results suggested that a moderate exposure to fungal spores, endotoxins, and beta(1-->3)-glucans during waste handling induced upper airway inflammation dominated by neutrophil infiltration and swelling of the nasal mucosa.