Assessment of Bioaerosol Transport at a Large Dairy Operation

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Proceedings available at: http://www.extension.org/67599

In an effort to assess the off-site transport of bioaerosols, airborne bacteria, fungi, and endotoxin were collected at a 10,000 cow dairy operation. Compared to background locations, the general trend was that bioaerosol concentrations were higher immediately downwind, then decreased with distance from the animal housing. While bioaerosol concentrations did not follow a seasonal trend, they did significantly correlate with meteorological factors such as temperature and solar radiation. Bioaerosol concentrations were also found to be greatest at night, which can be attributed to changes in animal activity and wind speed and reduced exposure of the microorganisms to UV radiation. An analysis of clones generated from air samples collected downwind from the animal housing and pivots spraying dairy wastewater revealed that none of sequence matches were affiliated with bacteria known to be pathogenic to otherwise healthy humans. Results from ongoing research to better understand bioaerosol formation and drift losses during spray irrigation events of dairy wastewater will also be discussed.

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Assessment of Bioaerosol Transport at a Large Dairy Operation

  1. 1. United States Department of AgricultureAgricultural Research ServiceAssessment of Bioaerosol Transport atLarge Dairy OperationsDrs. Robert S. Dungan, April Leytem, and David BjornebergNorthwest Irrigation & Soils Research LaboratoryKimberly, Idaho 83341robert.dungan@ars.usda.gov
  2. 2. United States Department of AgricultureAgricultural Research ServiceWhat are Bioaerosols?
  3. 3. United States Department of AgricultureAgricultural Research Service• Viable and nonviable airbornebiological particles and theirfragments/byproducts• Bacteria, virus, fungal spores,pollen, mycotoxin, endotoxin• Mixture of droplets and dryparticles• Aerodynamic diameters rangingfrom 0.5 to 100 µmBioaerosols
  4. 4. United States Department of AgricultureAgricultural Research ServiceBioaerosol Health Concerns• Bioaerosols < 5 µm in dia. present the most concernsince they are readily transported into the lungs• Microbial component of inhaled agricultural dustscontributes significantly to pulmonary diseases• Allergenic, toxic, and inflammatory responses arecaused not only by exposure to viable but alsononviable microorganisms and their fragments (e.g.endotoxin)• Bioaerosols < 5 µm in dia. present the most concernsince they are readily transported into the lungs• Microbial component of inhaled agricultural dustscontributes significantly to pulmonary diseases• Allergenic, toxic, and inflammatory responses arecaused not only by exposure to viable but alsononviable microorganisms and their fragments (e.g.endotoxin)
  5. 5. United States Department of AgricultureAgricultural Research ServiceBioaerosols Known to TravelGreat DistancesFoot-and-Mouth disease(FMD) transmission fromBrittany to Isle of Wightacross the EnglishChannel (1981)
  6. 6. United States Department of AgricultureAgricultural Research ServiceDairies as a Source of Bioaerosols• High stocking density and largequantities of manure (55 kg/day)• Increase in the microbial loadwithin the productionenvironment• Livestock harbor a variety ofzoonotic pathogens, which areexcreted with feces• Bioaerosols a potential healthrisk to livestock, farm workers,and those offsite
  7. 7. United States Department of AgricultureAgricultural Research ServiceFormation of Bioaerosols• Animal movement• Lot harrowing• Feed preparation• Land spreading ofmanure solids andwastewater• Compost turning
  8. 8. United States Department of AgricultureAgricultural Research ServiceViability of Airborne Microorganisms• Temperature• Solar radiation• Humidity• Temperature• Solar radiation• HumidityIn general, viability decreases with increases insolar radiation and temperature and decreases inrelative humidityIn general, viability decreases with increases insolar radiation and temperature and decreases inrelative humidity
  9. 9. United States Department of AgricultureAgricultural Research ServiceRole of Solids-Association inMicrobial SurvivalSobsey (1984)Embedded:most protectedEmbedded:most protectedDispersed: leastprotectedDispersed: leastprotectedAdsorbed:partiallyprotectedAdsorbed:partiallyprotectedClumped: interiormicrobes protectedClumped: interiormicrobes protected• Microbes can be on or in largerparticles or they can be aggregated• Association of microbes with solidsor particles and microbialaggregation is generally protective• Microbes are shielded fromenvironmental agents byassociation with solids
  10. 10. United States Department of AgricultureAgricultural Research Service10,000 Cow Open-Freestall Dairy• Aerosol samples werecollected in the morning,afternoon, and night• Spring, summer, and fall• Quantified heterotrophicbacteria, total coliforms ,E. coli, coliphage, fungi,and endotoxin• Bacterial DNA was usedto create a clone libraryof 16S rRNA genesN
  11. 11. United States Department of AgricultureAgricultural Research ServiceWetted-Wall CycloneWetted-Wall CycloneImpingerImpingerImpact SamplerImpact SamplerFilter SamplerFilter SamplerTechniques Used to Capture Bioaerosols
  12. 12. United States Department of AgricultureAgricultural Research ServiceAirborne BacteriaCFUm-3ofAirIndicators of fecalpollution generallynot detected (i.e.total coliforms, E.coli, and coliphage)
  13. 13. United States Department of AgricultureAgricultural Research ServiceCFUm-3ofAirDiurnal Effects: Airborne Bacteria
  14. 14. United States Department of AgricultureAgricultural Research ServiceAirborne Filamentous FungiCFUm-3ofAir
  15. 15. United States Department of AgricultureAgricultural Research ServiceCFUm-3ofAirDiurnal Effects: Airborne Fungi
  16. 16. United States Department of AgricultureAgricultural Research ServiceFacts About Airborne Endotoxin• Ubiquitous in the environment• Inhalation is the main route forexposure• Cough, airway irritation, anddecreased pulmonary function• At high exposure levels, feverand influenza-like symptomsmay develop• Some studies suggest a lowerrisk for asthma and lung cancer
  17. 17. United States Department of AgricultureAgricultural Research ServiceAverage Inhalable Endotoxin (< 100 µm)EUm-3ofAir
  18. 18. United States Department of AgricultureAgricultural Research ServiceDiurnal Effect: Airborne Endotoxin
  19. 19. United States Department of AgricultureAgricultural Research ServiceFactors Affecting AirborneEndotoxin ConcentrationsLotharrowingeventWind increased from1.9 to 4.5 m s-1Intermittentcow activityEUm-3ofAirHour Hour
  20. 20. United States Department of AgricultureAgricultural Research ServicePredicted Ground-LevelEndotoxin ConcentrationsEUm-3ofAirDownwind (m)
  21. 21. United States Department of AgricultureAgricultural Research ServiceEUm-3ofAirWindNDownwind (m)Empirical Endotoxin Data at anOpen-Lot Dairy
  22. 22. United States Department of AgricultureAgricultural Research ServiceComparison of Endotoxin LevelsEU m-3of Air
  23. 23. United States Department of AgricultureAgricultural Research ServiceItem Air Temp RelativeHumiditySolarRadiationWindspeedEndotoxin 0.318*** -0.150 -0.178* 0.074Bacteria 0.149* -0.166* -0.137* 0.165*Fungi 0.138* 0.117 -0.117 -0.246***Pearson Correlation Coefficients (r) BetweenBioaerosol and Meteorological Factors*, **, *** Indicate significant differences at 0.05,0.01, and 0.001 probability levels, respectively
  24. 24. United States Department of AgricultureAgricultural Research ServicePhylum Background Dairy barns andlotsPivots sprayingdairy wastewaterActinobacteria 3 (2%) 2 (4%)Bacteroidetes 2 (7%) 11 (8%) 4 (8%)Firmicutes 3 (10%) 13 (9%) 5 (10%)Proteobacteria 24 (83%) 111 (78%) 33 (69%)Unclassified 5 (3%) 4 (8%)Number (and Percentage) of Unique CloneSequences Affiliated With the Bacterial Phyla
  25. 25. United States Department of AgricultureAgricultural Research ServiceAcinetobacter Escherichia PlanococcusArthrobacter Georgenia PseudomonasBacteroides Halomonas RalstoniaBradyrhizobium Hymenobacter RhizobiumCaulobacter Jeotgalicoccus SkermanellaCellulomonas Marinobacter SphingomonasChryseobacterium Methylobacterium SphingopyxisClostridium Novosphingobium StaphylococcusCorynebacterium Paracoccus VariovoraxCommon Bacterial Genera in theDairy Aerosol Samples• Only 3% of the sequences were homologous withbacteria from cow milk, rumen, and fecal samples• No sequences were affiliated with bacteria known tobe pathogenic to non-immunocompromised individuals
  26. 26. United States Department of AgricultureAgricultural Research ServiceEvaporation/Aerosolization Dispersion InhalationRisk ofinfectionDeposition andbiological decayProduce and fomitesIngestionSmall droplets(< 150 µm)Large droplets (>150 µm)DepositionConceptual Model of Human Infectionfrom Land Application of Wastewater
  27. 27. United States Department of AgricultureAgricultural Research ServiceCampylobacter jejuni Clostridium perfringens E. coli (EHEC)Leptospira spp. Listeria monocytogenes MycobacteriumaviumSalmonella enterica YersiniapseudotuberculosisCryptosporidium/Giardia spp.Pathogens in Dairy Wastewaters
  28. 28. United States Department of AgricultureAgricultural Research ServiceEffect of Pressure and Spray Plate onMicroorganisms During Sprinkler Irrigation
  29. 29. United States Department of AgricultureAgricultural Research ServiceEvaluation of Center Pivot WindDrift and Evaporation Loss
  30. 30. United States Department of AgricultureAgricultural Research ServiceCapturing Aerosols, Drift, and Droplets
  31. 31. United States Department of AgricultureAgricultural Research ServiceWind Drift and Evaporation Results
  32. 32. United States Department of AgricultureAgricultural Research ServiceWind speed (m sec-1)0 1 2 3 4 5Percentappliedwateraerosolized0.00.51.01.52.02.5y = 1.3715x - 3.0323R2= 0.77Wind speed (m sec-1)0 1 2 3 4 5Percentappliedwaterasdrift0.10.20.30.40.50.60.7y = 0.2535x - 0.3052R2= 0.56Percent of Applied Water Aerosolized orMeasured as Drift as Affected by Wind Speed
  33. 33. United States Department of AgricultureAgricultural Research ServiceSummary and Concluding Remarks• Dairies are a source of elevatedbioaerosol concentrations, whichdecrease with increasing distance• The level of bioaerosol did not follow aseasonal trend, but did correlate withsome meteorological factors• Clone sequences were not affiliatedwith human pathogens• Risk of bioaerosol exposure should beminimal at extended downwinddistances
  34. 34. United States Department of AgricultureAgricultural Research ServiceThank you

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