- In a study published in the Journal of Applied and Environmental Microbiology, microbiologist Jie Zheng, Ph.D., and other FDA researchers explain how they set out to better understand how fresh tomatoes become contaminated with Salmonella. The researchers found that quality of the water is a key factor. Tomatoes can become contaminated at specific times during the growing season, indicating the importance of using clean water to irrigate at planting or when applying pesticides.
- In a study published in the journal BMC Microbiology, microbiologist Andrea Otteson, Ph.D., and FDA colleagues compared the tomato-growing environments of California, Virginia and Florida. The researchers are developing a baseline of microflora (including algae, fungi, and bacteria) associated with tomato crops at high or low risk of Salmonella contamination. The researchers are also considering other factors, such as the crops’ proximity to poultry farms—a potential source of Salmonella—or certain fungi in the soil. California has not had as many Salmonella outbreaks in tomatoes, and this research may be able to pinpoint the conditions on the East Coast that would be the safest for tomato crops, Otteson says.
The Practical Application So what does FDA do with all this information? The agency’s tomato research is shared on an ongoing basis with industry and agricultural extension systems at the state level. Steve Rideout, Ph.D., director of Virginia Tech’s AREC, says that he and his staff exchange research findings with FDA and share that information with growers. “There are still a lot of unknowns when it comes to contamination of tomatoes,” says Michael Mahovic, Ph.D., a consumer safety officer on FDA’s Produce Safety Staff. “But our research helps open a window.” Findings by FDA researchers were among the building blocks of the Proposed Produce Safety Rule mandated by the FDA Food Safety Modernization Act (FSMA), Mahovic says. The proposed rule would establish science-based standards for the production and harvesting of fruits and vegetables. FSMA gave FDA a mandate to implement a system that emphasizes prevention of risks to public health. The tomato industry has worked closely with FDA in setting its own safety standards, says David Gombas, Ph.D., senior vice president of the United Fresh Produce Association. Industry-wide safety guidelines were adopted in 2008. And in 2009, the industry issued food safety and auditing standards, commonly called the Tomato Metrics, for growers, greenhouse operators, and packers. Mahovic says FDA used these industry standards as the basis for its own draft guidance documents in 2009 that recommended ways in which microbial food safety hazards could be reduced throughout the tomato supply chain. Gombas says the tomato industry continues to have a close working relationship with FDA, with frequent meetings and conversations about the latest research. The industry provides FDA access to farms and crops. “We’re all working together on this,” he says. Studying the Genes There is another arm of this work for Team Tomato—researching the genes of the disease-causing bacteria. While the agency’s other research in field and lab focuses on preventing tomatoes from becoming contaminated, the goal of the gene research is to prevent illnesses once Salmonella is detected. FDA wants faster ways to track down the source of an outbreak of foodborne illnesses, explains Captain Thomas Hill, MPH, U.S. Public Health Service, an environmental health specialist in FDA’s Coordinated Outbreak Response Network, who is also a member of Team Tomato. “I come at this from the outbreak perspective. Part of our mission is to prevent the next outbreak.” Bell explains that the agency has been developing bacterial genetic sequences (the ordered chemical building blocks of DNA). This work will be part of a public database of bacterial gene sequences that will allow scientists to rapidly identify disease-causing bacteria and locate their source. “There has been a big data gap in the past, and we’re looking to correct that,” says Bell. Sound Science In addition to its focus on the prevention of foodborne illnesses, Team Tomato’s work advances another FDA priority: the use of sound science—in this case what we call regulatory science—to support the agency’s oversight of the nation’s food supply. “Team Tomato is one of the best examples of regulatory science that we have to offer,” says Brown. “The scientific information that Team Tomato has gleaned so far is helping to answer some very tough questions related to tomato safety and Salmonella in the farm environment.” Brown notes, “Considering the number of people who eat tomatoes, the rate of infection from Salmonella is very low. But it’s a very popular food, and we are determined to make that risk as low as possible.”