Purpose: To address this gap, the goal of our study was to identify and quantify the role of potential environmental contaminants (soil, irrigation water, farm worker hands) on produce contamination.
Methods: 161 produce (cantaloupe, jalapeño, tomatoes) and matched 89 irrigation water, 55 soil, and 106 farm worker hand rinse samples were collected from 14 farms on the Mexican side of the U.S.-Mexico border. Samples were quantified for generic E. coli, Enterococcus, and coliforms. Chi-square tests and logistic regression models (prevalence), Spearman’s correlations (non-normal data), and linear regression models (levels) were used to assess magnitude of association.
Results: In general, farm worker hands were significantly more likely to be positive for bacterial indicators, and at higher levels than soil and water. The presence of E. coli, but not Enterococcus or coliforms, was significantly associated between hands and produce (OR 7.9, 95% CI [3.3-19.1]). The levels of E. coli(rho=0.4), Enterococcus (rho=0.5), and coliforms (rho=0.6) were significantly and highly correlated between hands and produce. These trends were also observed when analyses were stratified at the individual produce type level. Unlike hands, the presence or levels of indicators on soil and water samples were not significantly and positively associated with the presence or levels of indicators on produce samples.
Significance: These results suggest that decreasing farm worker hand contamination would be an effective intervention to decrease microbial contamination of produce.