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UA Public Health Researchers Work to Keep U.S. Food Crops Safe

University of Arizona public health researchers received three grants totaling $400,000 to study E. coli contamination of irrigation water for food crops. The results of this research will benefit farmers and consumers by reducing food recalls due to pathogen contamination from irrigation water.

Working to keep U.S. food crops safe, a team of researchers from the University of Arizona Mel and Enid Zuckerman College of Public Health and College of Agriculture and Life Sciences has received funding to study irrigation water quality.

The team will focus on developing monitoring strategies and guidelines to provide food safety improvements that can be used by the U.S. produce industry to prevent crops from becoming contaminated.

Between 1998 and 2008 in the United States more than 3.2 million foodborne illnesses were attributed to vegetables contaminated by a pathogenic microorganism, leading to 233 deaths. When water contaminated with pathogens – any infectious agent such as a virus, bacterium or parasite – is used to irrigate produce, these pathogens can attach to the surface of produce or potentially be taken up by the roots into the edible plant.

The UA research team will focus on identifying the best strategies for monitoring irrigation water quality and the development of guidelines for the irrigation of food crops. Most of this work will be conducted in Yuma, Ariz., the principal U.S. region responsible for the production of leafy greens such as lettuces and spinach during the winter. In addition, the team will expand the geographical research to include irrigation systems in Imperial Valley, Calif., and Maricopa, Ariz., thereby increasing the agricultural impact and relevance for more farmers.

The team will develop a standard procedure and guidelines for sampling irrigation water used for food crops.

“In the greater picture, this will benefit the farmers and consumers of produce by reducing food recalls from pathogen contamination originating from irrigation water,” said Marc Verhougstraete, PhD, assistant professor of environmental health sciences at the UA Zuckerman College of Public Health.

“This research will help farmers to better monitor their water quality to determine if it is safe to use for the irrigation of produce,” said Kelly Bright, PhD, associate research professor in the UA College of Agriculture and Life Sciences.

Bright said the current standards used by the produce industry to detect fecal contamination in irrigation water are based on tests developed for drinking water and risk threshold levels established for recreational water. For this reason, the team will evaluate the accuracy of a new “virus indicator” and improve the methods required for monitoring irrigation and other surface water. Results will provide the produce industry with valuable exposure data on the presence/absence and quantity of fecal contamination that may be present in irrigation water.

“Ultimately, we want to improve the use of indicator organisms for evaluating irrigation water quality,” said Verhougstraete. “The results of this research will have a national impact on irrigation water monitoring and keeping our produce safe from E. coli and other pathogens.”

Two grants totaling $335,000 were awarded by the Center for Produce Safety (CPS), a nonprofit public benefit corporation dedicated to research, public education and outreach regarding produce food safety issues. The Arizona Department of Agriculture awarded a $60,000 grant.

The three funded studies and the UA interdisciplinary research teams working on them are:

• Enteric viruses as new indicators of human and cattle fecal contamination of irrigation waters (Center for Produce Safety, $221,000)
Principal Investigator Kelly R. Bright, PhD, Department of Soil, Water and Environmental Science, UA College of Agriculture and Life Sciences.
Co-Principal Investigators Marc Verhougstraete, PhD, and Kelly Reynolds, PhD, UA Mel and Enid Zuckerman College of Public Health

• Optimal strategies for monitoring irrigation water quality and the development of guidelines for the irrigation of food crops (Center for Produce Safety, $117,202)
Principal Investigator Marc Verhougstraete, PhD
Co-Principal Investigators Kelly R. Bright, PhD; Kelly Reynolds, PhD; and Channah Rock, PhD, UA Department of Soil, Water and Environmental Science and UA Maricopa Agricultural Center

• Spatial/temporal sampling of irrigation water (Arizona Department of Agriculture, $60,000)
Principal Investigator Kelly R. Bright, PhD
Co-Principal Investigators Marc Verhougstraete, PhD, and Kelly Reynolds, PhD

The University of Arizona