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Tuesday, August 13, 2013

‘Team Tomato’ researchers looking at ways
to rid popular produce of contamination risk

Tomatoes grown in Franklin County (Photo by Tim Thornberry)

Tomatoes grown in Franklin County (Photo by Tim Thornberry)


By Tim Thornberry
KyForward contributor

There’s good news and not-so-good news about tomatoes, one the most sought-after items in America’s produce aisles and farmers markets.

The good news, according to Elaine Magee, a registered dietician who writes for the website WebMD, is that tomatoes are healthy. The fruit/vegetable, of which the average American consumes about 22 pounds annually including in ketchup and tomato sauce, are full of potassium and vitamins. And some of the things in them likely help prevent some types of cancers, she said.

The not-so-good news is that, since 2000, there have been 12 multistate outbreaks of illnesses attributed to salmonella contamination of raw tomatoes, according to information from the Food and Drug Administration.

As a result, the agency has put together a team of research experts to try and find the reason(s) for these outbreaks. Team Tomato, as the group is known, is working to find a way to keep tomato contamination from occurring.


Eric Brown, the director of the Division for Microbiology in the Office of Regulatory Science at FDA’s Center for Food Safety and Applied Nutrition, said tomatoes present a huge challenge for safety in the food supply.

“They are a little bit unique. Number one, they are one of the most commonly consumed produce items in the country and probably in the world. Number two, they have a very short life cycle,” he said. “So tomatoes are grown, used for the fresh cut markets and eaten fresh, and when there’s an illness associated with tomatoes, by the time our investigators can get to the farm where the tomatoes may have come from, the tomatoes are gone.”

Brown said getting back to the source has been a struggle because outbreaks of illnesses connected to tomatoes are sporadic and usually don’t involve many people making it difficult to pinpoint a cause.

“We saw an emergence of tomato related illness that started in the late ’90s associated with salmonella and that became a fairly regular event,” he said. “In 2007 the FDA realized it was going to have to enlist some input from states and growers and it was time to have some serious discussions about the tomato problem.”

A tomato summit was held that same year in which industries from up and down the East Coast where many contaminations were concentrated, and extension people from many of the major agricultural universities convened to discuss what could be done to curb tomato-borne illness.

From that came the Team Tomato and the research it is conducting.

Rebecca Bell, an FDA research microbiologist and one of the lead researchers on the team, said an environmental survey was conducted in Virginia in 2009 with the help of Virginia Tech which has a research station along the Eastern Shore. In fact she said the research area was literally across the street from a commercial tomato farming operation.

“It was a great model for us to figure out what’s going on in this environment,” she said.

The thought was to raise tomatoes in an environment similar to those where tomatoes associated with previous illnesses had been grown, take samples of the plants and the surrounding areas, and even get samples from some of the surface waters and well waters.

“We knew that the salmonella was out there but the big question was where and how was it getting to the tomato plants,” said Bell.

The research in Virginia lasted for three years and now is focused in North Carolina to compare the two environments.

Bell said the FDA’s findings will contribute to the body of tomato safety science and help in the development of guidance for industry. She added the agency is actively pursuing ecologically friendly approaches to control salmonella contamination directly on the farm. One of those solutions is pitting naturally occurring bacteria that are harmless to humans against salmonella that persist on the farm and around tomato plants.

The work has yielded promising results. From at least 1,000 bacteria samples tested against salmonella, the team has discovered three natural organism candidates, one of which is exceptionally good at killing the bacterium while the other two are moderately good at the task.

“We are using these to basically try and block the uptake of Salmonella by some common routes of contamination; through the roots or through the blossoms,” Bell said.

On the source front, she noted that in doing the research, some common denominators have been discovered as it relates to salmonella.

“The main one is we find it in surface waters and sediments associated with those waters, at least in Virginia,” Bell said. “Our concern is that this may be a major risk factor, especially if you are using these waters at critical points in the tomato season. For example, if you’re using the water for spraying pesticides after the tomato plants have blossomed or right after transplanting.”

While a contaminated water source could be part of the problem, it is likely not the only culprit. Bell said another segment of Team Tomato looks at metagenomics. To do this, the FDA takes samples – from soils or tomato leaves for instance – and sequences the DNA associated with every micro-organisms in those samples to try and identify their genetic composition.

“We are simply looking at what is there genetically,” Bell said. “We have done this work with Florida, California and Virginia trying to get an idea of what is different in these growing regions.”

Brown said one of the interesting things the research has shown is that it looks as though there is a geographic clue in the salmonella that is probably revealing its home source. He said that Bell has developed a substantial data base that helps track a contamination event and the geographic sign in hopes the salmonella will lead investigators back to the region where the tomatoes were grown.

Mike Mahovic, a consumer safety officer on the produce safety staff in the FDA’s Office of Food Safety said much of the focus is on preventative controls. There are practices and ideas on different practices that are moving out to growers and the public to try and minimize the instances of salmonella contamination.

He said while there have not been any huge, widespread outbreaks associated with tomatoes, especially as it relates to the vast number of tomatoes produced each year, there are instances of outbreaks and the team tries to focus on specific risk factors and practices to minimize those risk factors.

Brown said, “We’re lucky we haven’t seen a wide-scale event but if one person gets sick from eating a fresh tomato, that’s one too many and we’re not going to stop until we get that number as low as we possibly can.”

For more information from the FDA about food safety, click here.

Tim Thornberry is a freelance writer and photographer who has covered Kentucky agricultural and rural issues for various publications since 1995. 



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