Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 791, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.148189
Keywords
Animal waste; Slurry; Bioaerosol; Risk assessment; QMRA, Ireland
Categories
Funding
- Department of Agriculture, Food and the Marine (DAFM) , Ireland [14/SF/847]
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This study developed a quantitative risk assessment model for Escherichia coli transmission through the air exposure route, predicting human exposure levels and emphasizing the importance of maintaining distance and waiting time to ensure occupational safety.
Transfer of Escherichia coli in bioaerosols to humans during and shortly after the land application of farmyard slurry may pose human health hazards, but it has not been extensively explored to date. The present study developed a quantitative risk assessment model for E. coli through the air exposure route. The probabilistic model assessed the predicted number of microorganisms in the air (PNair) to which humans may be exposed. A Gaussian air dispersion model was used to calculate the concentration of E. coli transmitted through aerosols. Human exposure (HE) to E. coli was estimated using a Monte Carlo simulation approach. This research predicted the mean HE as 26 CFU day(-1) (95th percentile 263 CFU day(-1)) and suggests the importance of keeping a distance of at least 100 m for the residential population from land spreading activities. However, the simulated mean daily or annual (once a year application) risk of 2.65 x 10(-7) person(-1) year(-1) due to land application of slurry indicates very low occupational risk for farmworkers not equipped with the personal protective equipment (PPE), who are potentially exposed to E. coli indirectly. The model found that the decay constant of E. coli in air, duration of decay, and bio-aerosolisation efficiency factor (top three) could influence HE to airborne E. coli. Furthermore, this research recommends an average time lag of at least 2.5 h following the application of farmyard slurry to the field before humans access the field again without PPE, allowing the airborne pathogen to decay, thereby ensuring occupational safety. The model suggested that the bio-aerosolisation efficiency factor (E) for other pathogens requires further investigation. The information generated from this model can help to assess likely exposure from bioaerosols triggered by land application of farmyard slurry. (C) 2021 The Author(s). Published by Elsevier B.V.
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