Concentration of bioaerosols in composting plants using different quantification methods.
BACKGROUND
Bioaerosols (organic dusts) containing viable and non-viable microorganisms and their metabolic products can lead to adverse health effects in exposed workers. Standard quantification methods of airborne microorganisms are mainly based on cultivation, which often underestimates the microbial burden. The aim of the study was to determine the microbial load in German composting plants with different, mainly cultivation-independent, methods. Second purpose was to evaluate which working areas are associated with higher or lower bioaerosol concentrations.


METHODS
A total of 124 inhalable dust samples were collected at different workplaces in 31 composting plants. Besides the determination of inhalable dust, particles, and total cell numbers, antigen quantification for moulds (Aspergillus fumigatus, Aspergillus versicolor, Penicillium chrysogenum, and Cladosporium spp.) and mites was performed. Concentrations of β-glucans as well as endotoxin and pyrogenic activities were also measured. The number of colony forming units (cfu) was determined by cultivation of moulds and actinomycetes in 36 additional dust samples.


RESULTS
With the exception of particle numbers, concentrations of all determined parameters showed significant correlations (P < 0.0001; r Spearman: 0.40-0.80), indicating a close association between these exposure markers. Colony numbers of mesophilic moulds and actinomycetes correlated also significantly with data of cultivation-independent methods. Exposure levels showed generally large variations. However, all parameters were measured highest in dusty working areas like next to the shredder and during processing with the exception of Cladosporium antigens that were found in the highest concentrations in the delivery area. The lowest concentrations of dust, particles, antigens, and pyrogenic activity were determined in wheel loader cabins (WLCs), which were equipped with an air filtration system.


CONCLUSIONS
It was possible to assess the microbial load of air in composting plants with different quantification methods. Since allergic and toxic reactions may be also caused by nonliving microorganisms, cultivation-independent methods may provide additional information about bioaerosol composition. In general, air filtration reduced the bioaerosol exposure shown in WLCs. Due to the fact that the mechanical processing of compost material, e.g. by shredding or sieving is associated with the generation of high bioaerosol concentrations, there is still a need of improved risk assessment and state-of-the-art protective measures in composting plants.
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany kampen@ipa-dguv.de.
Vera
V
van Kampen
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
Ingrid
I
Sander
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
Verena
V
Liebers
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
Anja
A
Deckert
2.German Social Accident Insurance, Institution for the public sector in North Rhine-Westphalia, St.-Franziskus-Straße 146, 40470 Düsseldorf, Germany.
Heinz-Dieter
HD
Neumann
2.German Social Accident Insurance, Institution for the public sector in North Rhine-Westphalia, St.-Franziskus-Straße 146, 40470 Düsseldorf, Germany.
Martin
M
Buxtrup
3.Berufsgenossenschaft für Transport und Verkehrswesen, Ottenser Hauptstr. 54, 22765 Hamburg, Germany.
Eckart
E
Willer
3.Berufsgenossenschaft für Transport und Verkehrswesen, Ottenser Hauptstr. 54, 22765 Hamburg, Germany.
Christian
C
Felten
4.Federal Institute for Occupational Safety and Health (BAuA), Nöldnerstrasse 40-42, 10317 Berlin, Germany.
Udo
U
Jäckel
4.Federal Institute for Occupational Safety and Health (BAuA), Nöldnerstrasse 40-42, 10317 Berlin, Germany.
Kerstin
K
Klug
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
Thomas
T
Brüning
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
Monika
M
Raulf
1.Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Buerkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
Jürgen
J
Bünger
D000336:Aerosols / Q000032:analysis; D000391:Air Microbiology; D000395:Air Pollutants, Occupational / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis; D001673:Biodegradation, Environmental; D004391:Dust / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D016273:Occupational Exposure / Q000032:analysis; D010316:Particle Size; D018570:Risk Assessment; D012498:Sanitary Engineering; D012987:Soil; D017132:Workplace
D000336:Aerosols; D000395:Air Pollutants, Occupational; D004391:Dust; D012987:Soil
bioaerosol; composting; cultivation-independent methods; microorganisms; organic dust; working areas