Reacting to the Tomato Scare: Overdone or Not Enough?

The number of Americans becoming sick from eating tomatoes contaminated with salmonella bacteria is rising. Douglas Powell, associate professor for food safety, discusses whether people are overreacting — or not reacting seriously enough — to such foodborne illnesses.

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In the meantime, we'll be talking about tomatoes and salmonella. Yesterday, the FDA admitted that the number of people sickened by salmonella-tainted tomatoes is bigger than they thought. At least 228 people in 23 states have gotten sick from eating suspect tomatoes, according to the CDC. That's the Centers for Disease Control and Prevention in Atlanta.

It's been nearly two weeks since the tomato-salmonella link first surfaced, and while consumers are cautioned to stay away from certain types of tomatoes, we still don't know the source of the outbreak. And there's a chance we may never know. So what's a consumer to do? The likelihood of you getting sick is pretty small, but statistics don't matter very much if you're headed to the emergency room because you chose the salsa instead of the guacamole.

Joining me now to talk more about this outbreak and food safety is my guest. Douglas Powell is an associate professor of food safety, and scientific director of the International Food Safety Network at Kansas State University in Manhattan, Kansas. He also writes the Barfblog, if you want to take a look at that before your next meal, which you might. Welcome to Science Friday, Dr. Powell.

Dr. DOUGLAS POWELL (Scientific Director, International Food Safety Network, Kansas State University): Thank you.

PALCA: And I gather you're not in Manhattan, Kansas, at the moment, is that right?

Dr. POWELL: No. We're driving back from Ontario and Quebec doing some work up here, although we're eager to get back, because Manhattan got here pretty good with the tornado a couple of nights ago.

PALCA: Well, I was just going to say, there's even reports, I think, even more recently of the tornadoes, but perhaps it will be interesting, or troubling, to see what you wind up going back to.

Dr. POWELL: Well, my thoughts are certainly with the people in Manhattan, and we're getting back there.

PALCA: Ah, OK. Well, Dr. Powell we're going to talk about tomatoes and safety, but first, I have to remind callers that they're listening to Talk of the Nation from NPR News. So, this whole question of food safety, I mean, there's, what? Two hundred and - how many hundred million people in America today eating how many hundreds of - hundreds of millions of tomatoes and 228 got sick, are we a bunch of a nation of nervous nellies?

Dr. POWELL: Well, as you mentioned in your prelude, statistically the risk may seem low, and certainly there are benefits that consuming a diet rich in fresh fruits and vegetables. If you're one of the 228, you're not very happy about this. And while there's 228 identified, with salmonella, we generally use the fact for about 38 or 40, so that's how many sick people there are, 220 times 40. So there's thousands of people sick in this thing.

PALCA: I see. Is this the kind of contamination that you hear about where they say, well, careful washing of your food and vegetables, or maybe if - you know, if you need to adding a wash of maybe a light acetic acid situation. Is that going to take care of the problem? Or is this more serious?

Dr. POWELL: This is a little more challenging. Fresh fruits and vegetables are good for us, but as we consume them more, it's become apparent that, today, they're probably the biggest source of food-borne illness in the United States. And the best estimates of that are, you know, up to 30 percent of the population. Seventy-six million, 80 million people get sick each year. Fresh fruits and vegetables are the biggest source, and the reason why is because they're fresh. We don't cook them.

So anything that comes in to contact has the potential to contaminate. Now, with - there's some particular ones that keep popping up, and tomatoes is one of them. And with tomatoes, in past outbreaks, anyway, it's been shown that things like salmonella can actually get on the inside. So washing is of limited effect. That's important, but it is of limited effect, and this stuff really needs to be controlled on the farm.

PALCA: I'd like to invite our - we don't have much time left today, but if our listeners have a call, the number is 800-989-8255. That's 800-989-TALK. Is there - is there a chance - I mean, who - is it possible we will never know what happened here? Or do you have a guess of what's happened in this particular outbreak?

Dr. POWELL: It's possible we'll never know. You know, when spinach happened in the fall of 2006, the Food and Drug Administration was criticized because they basically took fresh spinach off the market. So in an attempt not take all tomatoes off the market, they said, OK, if you're from these regions, it's OK. But it's taken awhile to sort that out, because all of - you know, whether it's food service or grocery stores, they're buying tomatoes from all over the place. They're putting - mixing them together and putting them out for sale.

So it's taken awhile to work through the system. I think you're starting to see tomatoes coming back even as early as today, Burger King announced. And that's because they're saying, OK, now we know exactly where they're coming from, not a problematic area, so we can do it. Meanwhile, the investigative work goes on. How far back (unintelligible), hard to tell.

PALCA: OK. Well, let's take a quick call now and go to Hugh in Oakland, California. Hugh, welcome to Science Friday.

HIGH (Caller): Hi. Your speaker mentioned what's happening on the farm, which almost never gets discussed. We're hearing about what's happening and what's being done afterward to neutralize, but where are these bugs coming from? In the spinach scare, the E. coli was traced back, of course, to fertilizer and cattle that eat what their supposed to, that is, natural grass. Apparently, based on a program and forum on our local KQED station, we heard, at the time, that cattle eating grass do not produce E. coli. However, when they're eating grains they do. Is that possible with the salmonella source of fertilizer?

PALCA: Hm. OK. Hugh, thanks for the question.

Dr. POWELL: With the spinach outbreak, actually, the best guess of the source was cattle eating grass. It's a bit of a mythology to think that grass-fed cattle don't carry bugs like E. coli. They're present in 10 percent of all ruminids, grass-fed or not. Now, with salmonella, there's - main sources are animals, also birds and humans. So when we're on the farm, we try to control water, soil amendments, and that is manure, water coming in to contact with manure, and human cleanliness, human hygiene. Those are the main points to focus on.

PALCA: All right. Well, Doug Powell, it's an interesting discussion, and I thank you for coming along to help us sort some of these issues out. I'm sorry we didn't have more time, but we're going to have to leave it there. So thanks, and nice to talk to you again.

Dr. POWELL: OK. Thanks very much, Joe.

PALCA: Douglas Powell is an associate professor of food safety and scientific director at the International Food Safety Network at Kansas State University in Manhattan, Kansas. Greg Smith composed our theme music. We had help today from NPR librarian Kee Malesky. Nathan Barke is our technical director.

If you have comments or questions, write to us at Science Friday, 4 West 43rd Street, Room 306, New York, New York, 10036, or you can email us. The address is scifri@npr.org. Check out sciencefriday.com for more information and links to today's program. You can listen to the past editions of Science Friday online, or take them with you as a podcast, and check out Science Friday's Kids Connection, free curriculum materials for teaching science using Science Friday. Just click on the teachers link on sciencefriday.com. Ira Flatow will be back next week. For NPR News in Washington, I'm Joe Palca.

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Tomatoes Off Menus Amid Salmonella Outbreak

What to Avoid

Preliminary data suggest that raw, red tomatoes are the cause of a salmonella outbreak that has infected at least 145 people nationwide since mid-April, according to the Food and Drug Administration. At least 23 people have been hospitalized.

  

Salmonella is a bacteria that lives in the intestinal tracts of humans and other animals. The bacteria usually are transmitted to humans by eating foods contaminated with animal feces.

  

Most infected people suffer fever, diarrhea and abdominal cramps starting 12 to 72 hours after infection. The illness tends to last four to seven days. The Centers for Disease Control and Prevention estimates that for every reported case, 30 more cases go unreported.

  

For now, the FDA advises the following:

  

— Cherry, grape and homegrown tomatoes, and tomatoes sold with vines still attached are considered safe.

  

— Avoid raw Roma, plum and red round tomatoes.

  

— Avoid fresh salsa, guacamole and pico de gallo, which often contain raw tomatoes.

  

— Safety experts say it's not possible to reliably wash off salmonella. But cooking tomatoes will destroy the bacteria.

  

Compiled from NPR reports and The Associated Press

McDonald's "Big N' Tasty" sandwich is a little smaller Tuesday, and the Chicken Ranch BLT has temporarily lost its "T." Tomatoes are under scrutiny as the possible culprit in a salmonella outbreak that has sickened at least 145 people in more than a dozen states.

Federal health officials are trying to pinpoint the source of the contamination, and in the meantime, several restaurant chains, including McDonald's and Chipotle Mexican Grill, have stopped using fresh tomatoes altogether as a precaution. Wal-Mart, Winn-Dixie and other supermarkets have also pulled some types of tomatoes from their produce aisles.

The Food and Drug Administration is urging consumers to avoid raw Roma, plum and red round tomatoes. So far, investigators know that cherry tomatoes, grape tomatoes and tomatoes sold with the vines still attached have not been implicated by people who have gotten sick.

The salmonella outbreak has cast a dark cloud over tomato fields in Florida, where half the nation's fresh tomatoes are grown. Michael Stuart, president of the Florida Fruit and Vegetable Association, says if the investigation drags on, farmers could be left with unsold tomatoes rotting on the vine.

"They're extremely frustrated in that business has basically ground to a halt at this point in time," he says. "We're anxiously awaiting a determination by the Food and Drug Administration as to what the specific source of this problem is. And until that happens, quite frankly, we're dead in the water."

That's bad news for the 33,000 workers who help to harvest the Florida crop. The FDA has cleared tomatoes from California and seven other states, but only because those tomatoes hadn't ripened yet when the outbreak began in mid-April. Since then, at least 23 salmonella victims have been hospitalized.

Until officials figure out where the salmonella came from, consumers are advised to eat only the cherry and grape varieties or tomatoes still on the vine.

Simply cleaning tomatoes is not a reliable way to get rid of the salmonella bacteria, says food safety expert Tom Chestnut of NSF International.

Washing fruits and vegetables is a good way to reduce bacteria on the outside, "but it's very difficult to get a total elimination," he says.

Reporting by Scott Horsley and Allison Aubrey.

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