Science-based monitoring for produce safety: Comparing indicators and pathogens in water, soil and crops.

Science-based monitoring for produce safety: Comparing indicators and pathogens in water, soil and crops.

Dec. 31, 2009 - Jan. 31, 2013

$178,700.00

Osnat Gillor, Ph.D.
Ben-Gurion University of the Negev

Nirit Bernstein, Ph.D., Patricia A. Conrad, Ph.D., Woutrina Miller, Ph.D., Karen Shapiro, Ph.D., Stefan Wuertz, Ph.D.

Final Report

Technical Abstract

Fecal pathogens have been implicated in numerous disease outbreaks, as well as chronic gastrointestinal illness, in people who consume food that has been irrigated with reclaimed wastewater. With growing water scarcity problems affecting many regions, including the Middle East and the United States, the risk of produce contamination is likely to rise to increasing use of reclaimed wastewater for irrigation practices. To date, the most common water monitoring practice for fecal contamination in irrigation waters relies on culturing fecal indicator bacteria such as Escherichia coli. However, numerous studies have recently raised concerns that fecal indicators may not always correlate with levels of disease-causing fecal pathogens in water sources, including treated wastewater effluents. The inability of indicators to accurately predict whether fecal pathogens are present or absent in treated wastewater, as well as on the irrigated crops themselves, suggests that current monitoring guidelines are not adequate for protecting consumers from contaminated produce. Thus, there is a crucial need for improving produce safety monitoring strategies to ensure that the use of reclaimed wastewater in irrigation is a sustainable and safe practice in arid climates. The aim of this proposal is to examine the correlation between fecal indicators and a suite of fecal pathogens that may be found in irrigation wastewater, the irrigated soil and the cultivated plants. Specifically, the project will evaluate if current monitoring techniques that target fecal indicator organisms accurately predict the presence of fecal pathogens (bacteria, protozoa and viruses) on produce using wastewater irrigated tomatoes as our model plant cultivated in plots constructed for the purpose of this project. The specific objectives will 1) evaluate if fecal indicators in water and/or soil can accurately predict degree and type of pathogen contamination in plant tissues; and 2) test for a correlation between fecal indicators and the degree and type of pathogen contamination in irrigation water, soil, and plants. To accomplish this work, we have assembled a synergistic collaborative team with expertise in microbiology, waterborne infectious disease, and plant science. Findings from the study will have immediate application potential to agriculture management and public health policy makers by providing science-based monitoring guidelines for optimal microbial sampling strategies needed to protect consumers from exposure to disease-causing microorganisms on fruits and vegetables.