Annals of Occupational Hygiene Advance Access originally published online on June 26, 2009
Annals of Occupational Hygiene 2009 53(6):595-603; doi:10.1093/annhyg/mep040
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Exposure to Inhalable Dust, Endotoxins, β(1
3)-Glucans, and Airborne Microorganisms in Horse Stables
1 Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, PO Box 80178, 3508 TD Utrecht, The Netherlands
2 Occupational Health Department, Medical Faculty, University of Medical Sciences, Arak Islamic Republic of Iran, Arak
3 Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Marburglaan 2, 3584 CN Utrecht, The Netherlands
* Author to whom correspondence should be addressed. Tel: +31-30-253-1468; fax: +31-30-253-9499; e-mail: S.Samadi{at}uu.nl
Objectives: Workers in horse stables are likely exposed to high levels of organic dust. Organic dusts play a role in increased risk of inflammatory reactions and are associated with respiratory diseases. The aim of this study was to investigate dust, endotoxin, β(1
3)-glucan, and culturable microorganisms exposure levels in horse stables.
Methods: Ambient (n = 38) and personal (n = 42) inhalable dust samples were collected using PAS-6 sampling heads. As a special measurement, we included sampling near the horses heads. Samples were analyzed for endotoxin and β(1
3)-glucan by Limulus amebocyte lysate assay and an inhibition enzyme immunoassay, respectively. Culturable bacteria and fungi were collected with an Anderson impactor.
Results: Geometric means (GMs) of personal exposure to dust, endotoxin, and β(1
3)-glucan were 1.4 mg m–3 (range 0.2–9.5), 608 EU m–3 (20–9846), and 9.5 µg m–3 (0.4–631 µg m–3), respectively. Exposure levels in the morning shift were higher compared to other shifts. The GMs (ranges) of culturable bacteria and fungi were 3.1 x 103 colony-forming unit (CFU) m–3 (6.7 x 10 to 1.9 x 104) and 1.9 x 103 CFU m–3 (7.4 x 10 to 2.4 x 104), respectively. Variance components for endotoxin and β(1
3)-glucan were considerably higher than for dust. Based on dummy variable in a mixed regression analysis, the predominant task explaining exposure levels of dust, endotoxin, and β(1
3)-glucan was sweeping the floor. For β(1
3)-glucan, feeding the horse was also an important determinant.
Conclusion: Dust, endotoxin, and β(1
3)-glucan exposure are considerable in horse stables. Bacterial and fungal exposure levels were moderate. Endotoxin exposures were above the Dutch proposed standard limits, suggesting workers in horse stables to be at risk of adverse health effects.
Keywords: dust endotoxin glucan microorganism stables variance components
Received January 16, 2009; in final form May 26, 2009