Size-selective assessment of agricultural workers' personal exposure to airborne fungi and fungal fragments

Fungi are ubiquitous agents that cause human respiratory diseases. Very few studies have size-selectively assessed farmers' exposure to fungi and fungal fragments in agricultural settings. In this study, a two-stage bio-aerosol cyclone personal sampler was employed to collect airborne fungi and fungal fragments size-selectively at corn, swine, poultry, and mushroom farms. The collected air samples were analyzed for culturable fungi, fungal spores, viable fungi and (1 -> 3)-beta-D-glucan. The results show that the median concentrations ranged from 3.2 x 10(5) to 1.3 x 10(8) spores/m(3) for total fungal spores, from 1.3 x 10(5) to 5.1 x 10(7) spores/m(3) for total viable fungi, from 1.9 x 10(3) to 1.5 x 10(7) CFU/m(3) for total culturable fungi, and from 4.3 x 10(3) to 2.4 x 10(6) pg/m(3) for total (1 -> 3)-beta-D-glucan. The aerodynamic sizes of most of the collected fungal contaminants were larger than 1.8 mu m. Total (1 -> 3)-beta-D-glucan significantly correlated with total fungal spores (r = 0.65, p < 0.001), total viable fungi (r = 0.68, p < 0.001) and total culturable fungi (r = 0.72, p < 0.001). Total (1 -> 3)-beta-D-glucan significantly correlated with Aspergillus/Penicillium, Alternaria, and Cladosporium. Alternaria and Botrytis were also found to highly correlate with (1 -> 3)-beta-D-glucan at the size < 1 mu m, which was less than the expected spore sizes (the mean measured aerodynamic sizes were 18.5 mu m for Altemaria and 6.1 mu m for Botrytis); therefore, Altemaria and Bottytis might release small fragments that could enter the deep lung and cause respiratory diseases. (C) 2013 Elsevier B.V. All rights reserved.