Exposure to Grain Dust and Microbial Components in the Norwegian Grain and Compound Feed Industry

Objectives: The aim of this study was to extensively characterize grain workers ’ personal expo-sure during work in Norwegian grain elevators and compound feed mills, to identify differences in exposures between the workplaces and seasons, and to study the correlations between different microbial components. Methods: Samples of airborne dust (n = 166) were collected by full-shift personal sampling during work in 20 grain elevators and compound feed mills during one autumn season and two winter seasons. The personal exposure to grain dust, endotoxins, β-1→3-glucans, bacteria, and fungal spores was quantified. Correlations between dust and microbial components and differences between workplaces and seasons were investigated. Determinants of endotoxin and β-1→3-glucan exposure were evaluated by linear mixed-effect regression modeling. Results: The workers were exposed to an overall geometric mean of 1.0 mg m−3 inhalable grain dust [geometric standard deviation (GSD) = 3.7], 628 endotoxin units m−3 (GSD = 5.9), 7.4 µg m−3 of β-1→3-glucan (GSD = 5.6), 21 × 104 bacteria m−3 (GSD = 7.9) and 3.6 × 104 fungal spores m−3 (GSD = 3.4). The grain dust exposure levels were similar across workplaces and seasons, but the microbial content of the grain dust varied substantially between workplaces. Exposure level