Potential for microbial contamination of spinach through feedyard air/dust growing in close proximity to cattle feedyard operationS

To determine if spinach grown near cattle feedyards can become contaminated with microorganisms, fresh spinach bundles were set upright in polyvinyl chloride pipes within a feedyard. Bundles were located at 0, 20 and 50 yards from the cattle loadout area (dust generation). Control samples were in a Rubbermaid box (Rubbermaid, Huntersville, NC) to prevent environmental contamination. All samples were tested for generic Escherichiacoli, E.coli O157 and Salmonella after 6, 12 and 24h of feedyard exposure. Generic E.coli levels in exposed spinach placed at 0 yards increased by 2.5, 2.6 and 2.7 logs after 6, 12 and 24h, respectively. These increases were significant when compared with control samples (P=0.0456). At 20 and 50 yards, there was an increase in generic E.coli, with significantly less E.coli on spinach placed at farther distances. After 24h, 50-yard samples contained 12.96 logs less Salmonella than 0-yard samples. PRACTICAL APPLICATIONS: The results obtained from this research can serve as evidence for the spinach and leafy green industries that growing within the vicinity of cattle increases the likelihood of microbial contamination onto the product. Furthermore, this study serves as a foundation for future studies to identify exactly how close spinach and leafy green fields can be located to cattle feedyards without posing a risk for contamination via dust, soil and air. Such information is necessary in order to reduce the amount of product recalls, outbreaks and foodborne illnesses associated with the consumption of spinach and other leafy green vegetables.