Levels of bacterial endotoxin in the samples of settled dust collected in animal houses

Samples of settled dust were collected in 14 animal houses and examined for the presence of bacterial endotoxin with the Limulus (LAL) test and the gas chromatography - tandem mass spectrometry (GC-MSMS) technique, based on the detection of 3- hydroxy fatty acids (3-OH-FAs) as chemical markers of the endotoxin lipopolysaccharide. The median concentrations of the endotoxin in dust determined with LAL test in sheep sheds, poultry houses, and horse stables were 15,687.5 µg/g, 8,081.8 µg/g, and 79.3 µg/g, respectively, while those determined with the GC-MSMS technique were 868.0 µg/g, 580.0 µg/g, and 496.0 µg/g, respectively. Statistical comparison of the results yielded with LAL test and GC-MSMS technique revealed a weak correlation between both methods. Fatty acids with 14-16 carbon chains (3-OH-C₁₄ and 3-OH-C₁₆) were predominant in the settled dust of the facilities under study. In conclusion, endotoxin in the concentrations detected in this study may present a respiratory hazard to both livestock animals and farm workers. Thus, the prevention measures aiming to lower the exposure to endotoxin in livestock facilities are highly desirable.