assessment of bioaerosol transport at a large dairy operation

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United States Department of Agriculture Agricultural Research Assessment of Bioaerosol Transport at Large Dairy Operations Drs. Robert S. Dungan, April Leytem, and David Bjorneberg Northwest Irrigation & Soils Research Laboratory Kimberly, Idaho 83341 [email protected]

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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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Page 1: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Assessment of Bioaerosol Transport at Large Dairy Operations

Drs. Robert S. Dungan, April Leytem, and David Bjorneberg

Northwest Irrigation & Soils Research LaboratoryKimberly, Idaho 83341

[email protected]

Page 2: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

What are Bioaerosols?

Page 3: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

• Viable and nonviable airborne biological particles and their fragments/byproducts

• Bacteria, virus, fungal spores, pollen, mycotoxin, endotoxin

• Mixture of droplets and dry particles

• Aerodynamic diameters ranging from 0.5 to 100 m

Bioaerosols

Page 4: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Bioaerosol Health Concerns

• Bioaerosols < 5 m in dia. present the most concern since they are readily transported into the lungs

• Microbial component of inhaled agricultural dusts contributes significantly to pulmonary diseases

• Allergenic, toxic, and inflammatory responses are caused not only by exposure to viable but also nonviable microorganisms and their fragments (e.g. endotoxin)

• Bioaerosols < 5 m in dia. present the most concern since they are readily transported into the lungs

• Microbial component of inhaled agricultural dusts contributes significantly to pulmonary diseases

• Allergenic, toxic, and inflammatory responses are caused not only by exposure to viable but also nonviable microorganisms and their fragments (e.g. endotoxin)

Page 5: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Bioaerosols Known to Travel Great Distances

Foot-and-Mouth disease (FMD) transmission from Brittany to Isle of Wight across the English Channel (1981)

Page 6: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Dairies as a Source of Bioaerosols

• High stocking density and large quantities of manure (55 kg/day)

• Increase in the microbial load within the production environment

• Livestock harbor a variety of zoonotic pathogens, which are excreted with feces

• Bioaerosols a potential health risk to livestock, farm workers, and those offsite

Page 7: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Formation of Bioaerosols

• Animal movement• Lot harrowing • Feed preparation• Land spreading of

manure solids and wastewater

• Compost turning

Page 8: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Viability of Airborne Microorganisms

• Temperature

• Solar radiation

• Humidity

• Temperature

• Solar radiation

• Humidity

In general, viability decreases with increases in solar radiation and temperature and decreases in relative humidity

In general, viability decreases with increases in solar radiation and temperature and decreases in relative humidity

Page 9: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Role of Solids-Association in Microbial Survival

Sobsey (1984)

Embedded: most protected

Embedded: most protected

Dispersed: least protected

Dispersed: least protected

Adsorbed: partially

protected

Adsorbed: partially

protected

Clumped: interior microbes protectedClumped: interior

microbes protected

• Microbes can be on or in larger particles or they can be aggregated

• Association of microbes with solids or particles and microbial aggregation is generally protective

• Microbes are shielded from environmental agents by association with solids

Page 10: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

10,000 Cow Open-Freestall Dairy

• Aerosol samples were collected in the morning, afternoon, and night

• Spring, summer, and fall• Quantified heterotrophic

bacteria, total coliforms , E. coli, coliphage, fungi, and endotoxin

• Bacterial DNA was used to create a clone library of 16S rRNA genes

N

Page 11: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Wetted-Wall CycloneWetted-Wall CycloneImpingerImpinger

Impact Sampler Impact Sampler Filter SamplerFilter Sampler

Techniques Used to Capture Bioaerosols

Page 12: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Airborne BacteriaCF

U m

-3 o

f Air

Indicators of fecal pollution generally not detected (i.e. total coliforms, E. coli, and coliphage)

Page 13: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

CFU

m-3

of A

ir

Diurnal Effects: Airborne Bacteria

Page 14: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Airborne Filamentous Fungi

CFU

m-3

of A

ir

Page 15: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

CFU

m-3

of A

ir

Diurnal Effects: Airborne Fungi

Page 16: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Facts About Airborne Endotoxin

• Ubiquitous in the environment• Inhalation is the main route for

exposure• Cough, airway irritation, and

decreased pulmonary function• At high exposure levels, fever

and influenza-like symptoms may develop

• Some studies suggest a lower risk for asthma and lung cancer

Page 17: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Average Inhalable Endotoxin (< 100 m)

EU m

-3 o

f Air

Page 18: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Diurnal Effect: Airborne Endotoxin

Page 19: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Factors Affecting Airborne Endotoxin Concentrations

Lot harrowing event

Wind increased from 1.9 to 4.5 m s-1

Intermittent cow activityEU

m-3

of A

ir

Hour Hour

Page 20: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Predicted Ground-Level Endotoxin Concentrations

EU m

-3 o

f Air

Downwind (m)

Page 21: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

EU m

-3 o

f Air

WindN

Downwind (m)

Empirical Endotoxin Data at an Open-Lot Dairy

Page 22: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Comparison of Endotoxin Levels

EU m-3 of Air

Page 23: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Item Air Temp Relative Humidity

Solar Radiation

Wind speed

Endotoxin 0.318*** -0.150 -0.178* 0.074

Bacteria 0.149* -0.166* -0.137* 0.165*

Fungi 0.138* 0.117 -0.117 -0.246***

Pearson Correlation Coefficients (r) Between Bioaerosol and Meteorological Factors

*, **, *** Indicate significant differences at 0.05, 0.01, and 0.001 probability levels, respectively

Page 24: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Phylum Background Dairy barns and lots

Pivots spraying dairy wastewater

Actinobacteria 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 Clone Sequences Affiliated With the Bacterial Phyla

Page 25: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Acinetobacter Escherichia PlanococcusArthrobacter Georgenia Pseudomonas Bacteroides Halomonas RalstoniaBradyrhizobium Hymenobacter Rhizobium Caulobacter Jeotgalicoccus SkermanellaCellulomonas Marinobacter Sphingomonas Chryseobacterium Methylobacterium Sphingopyxis Clostridium Novosphingobium StaphylococcusCorynebacterium Paracoccus Variovorax

Common Bacterial Genera in the Dairy Aerosol Samples

• Only 3% of the sequences were homologous with bacteria from cow milk, rumen, and fecal samples

• No sequences were affiliated with bacteria known to be pathogenic to non-immunocompromised individuals

Page 26: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Evaporation/ Aerosolization Dispersion Inhalation

Risk of infection

Deposition and biological decay

Produce and fomites

Ingestion

Small droplets (< 150 m)

Large droplets (> 150 m)

Deposition

Conceptual Model of Human Infection from Land Application of Wastewater

Page 27: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Campylobacter jejuni Clostridium perfringens E. coli (EHEC)

Leptospira spp. Listeria monocytogenes Mycobacterium avium

Salmonella enterica Yersinia pseudotuberculosis

Cryptosporidium/Giardia spp.

Pathogens in Dairy Wastewaters

Page 28: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Effect of Pressure and Spray Plate on Microorganisms During Sprinkler Irrigation

Page 29: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Evaluation of Center Pivot Wind Drift and Evaporation Loss

Page 30: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Capturing Aerosols, Drift, and Droplets

Page 31: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Wind Drift and Evaporation Results

Page 32: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Wind speed (m sec-1)

0 1 2 3 4 5

Pe

rce

nt a

pp

lied

wa

ter

ae

roso

lize

d

0.0

0.5

1.0

1.5

2.0

2.5

y = 1.3715x - 3.0323R2 = 0.77

Wind speed (m sec-1)

0 1 2 3 4 5

Pe

rcent a

pp

lied w

ater a

s drift

0.1

0.2

0.3

0.4

0.5

0.6

0.7

y = 0.2535x - 0.3052R2 = 0.56

Percent of Applied Water Aerosolized or Measured as Drift as Affected by Wind Speed

Page 33: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Summary and Concluding Remarks

• Dairies are a source of elevated bioaerosol concentrations, which decrease with increasing distance

• The level of bioaerosol did not follow a seasonal trend, but did correlate with some meteorological factors

• Clone sequences were not affiliated with human pathogens

• Risk of bioaerosol exposure should be minimal at extended downwind distances

Page 34: Assessment of Bioaerosol Transport at a Large Dairy Operation

United States Department of Agriculture

Agricultural Research Service

Thank you