Assessing the Potential for Human Pathogen Contamination of Agricultural Fields by Dust From Animal Feeding Operations

Fugitive dust from concentrated animal feeding operations (CAFOs) is a potential source of produce contamination with human pathogens. Our objective was to develop a general framework and methodology for predicting preharvest produce contamination with human pathogens arising from fugitive dust derived from a nearby CAFO. We applied this framework to a case study of lettuce grown in proximity to a bovine CAFO. We implemented the EPA's AERMOD dispersion model at two locations, assessing dust dispersion and deposition over a 30-day period across 100 km² surrounding a 10,000-animal CAFO. E. coli O157:H7 contaminated lettuce servings grown on fields within the 100 km² were predicted using a risk assessment approach, integrating data about dust deposition, pathogen contamination in cattle manure, and pathogen survival on crops. To contextualize the results, infectious servings were predicted based on the average number of E. coli O157:H7 per serving and the E. coli O157:H7 dose-response relationship. Dust from CAFOs has the potential to deposit across at least 100 km². E. coli O157:H7 dispersion and deposition are impacted by wind direction and velocity, emission factor, and prevalence and concentration in dust. Mean E. coli O157:H7 concentrations on preharvest lettuce were predicted across the 100 km² and declined considerably with distance from the CAFO. Surviving E. coli O157:H7 on preharvest lettuce arise primarily from dust deposited in the 2 weeks before harvest. Our modeling approach provides a flexible framework that can be adapted to any location, providing quantitative information to inform foodborne outbreak investigations and the development of prevention strategies.