Bioaerosol Deposition to Food Crops near Manure Application: Quantitative Microbial Risk Assessment

Abstract

Production of both livestock and food crops are central priorities of agriculture; however, food safety concerns arise where these practices intersect. In this study, we investigated the public health risks associated with potential bioaerosol deposition to crops grown in the vicinity of manure application sites. A field sampling campaign at dairy manure application sites supported the emission, transport, and deposition modeling of bioaerosols emitted from these lands following application activities. Results were coupled with a quantitative microbial risk assessment model to estimate the infection risk due to consumption of leafy green vegetable crops grown at various distances downwind from the application area. Inactivation of pathogens ( spp., spp., and O157:H7) on both the manure-amended field and on crops was considered to determine the maximum loading of pathogens to plants with time following application. Overall median one-time infection risks at the time of maximum loading decreased from 1:1300 at 0 m directly downwind from the field to 1:6700 at 100 m and 1:92,000 at 1000 m; peak risks (95th percentiles) were considerably greater (1:18, 1:89, and 1:1200, respectively). Median risk was below 1:10,000 at >160 m downwind. As such, it is recommended that a 160-m setback distance is provided between manure application and nearby leafy green crop production. Additional distance or delay before harvest will provide further protection of public health.

Microorganisms Move a Short Distance into an Almond Orchard from an Adjacent Upwind Poultry Operation

“…Birds and insects have the potential to move pathogens from animal operations into growing environments ( 7 – 12 ). Bioaerosols capable of carrying pathogenic bacteria have been described to occur in cattle feedlots, in poultry and swine houses, and during field application of manure ( 13 – 18 ). Airborne generic Escherichia coli was found both inside and immediately outside poultry houses; levels of E. coli in the air were linked to the levels found in the litter ( 19 ).…”

Airborne bacterial emission fluxes from manure‐fertilized agricultural soil

“…Only limited research has measured emissions of bioaerosols from cattle and pig slurry during its land application (Boutin et al ., 1988; Hobbs et al ., 2004). One recent study had recommended a minimum distance of 160 m between manure application sites and any fields growing food crops, to avoid contamination with pathogens from manure (Jahne et al ., 2016). Our atmospheric modelling results suggested, however, that transport trajectories of emissions depend on prevailing atmospheric conditions, which could change during the day and result in the transport of manure particles over hundreds of kilometres.…”

Quantitative microbial risk assessment and sensitivity analysis for workers exposed to pathogenic bacterial bioaerosols under various aeration modes in two wastewater treatment plants

“…coli , respectively ( Oppliger et al, 2005 ; Szyłak-Szydłowski et al, 2016 ; Nasir et al, 2018 ; Wang et al, 2019 ). A 27 mL aliquot of this sterile agar media (autoclaved at 121 °C for 15 min) was pipetted into sterile glass Petri dishes equipped with the cascade impactor ( Jahne et al, 2015 ; Jahne et al, 2016 ).…”