A tale of two tomatoes

How and why, in a centralized food system,
a little bacteria can go a long way.

By Melinda Hemmelgarn, M.S., R.D.

In the winter and early spring, commercially grown “fresh-market” tomatoes typically travel hundreds of miles from their roots in Florida and Mexico. Picked green, they ripen en route with an expected shelf life of two to four weeks.

Increasing year-round consumer demand places tomatoes fourth (and climbing) on the most popular fresh-market vegetable list. So it was with heavy hearts that we learned the food-safety fiasco du jour involves tomatoes and Salmonella.

Not exactly what you’d expect from tomatoes, right? Salmonella typically conjures up thoughts of undercooked chicken and raw eggs, with good reason. Most of the 40,000 or so under-reported cases of Salmonellosis in the United States each year are associated with foods of animal origin.

That’s because Salmonella are a group of bacteria that live in the intestinal tracts of humans and other animals, including birds and reptiles. According to the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC), the bacteria usually spread by eating foods contaminated with human or animal feces. Keep that in mind.

A mystery unfolds

Tomatoes have been implicated in Salmonella outbreaks since 1990. But during the past decade, fresh and fresh-cut tomatoes have been linked to more than a dozen different outbreaks and near 2,000 confirmed cases of food-borne illness in the United States.

The current ongoing nationwide outbreak—277 cases reported in 23 states and counting—implicates three types of fresh (raw) tomatoes contaminated with the uncommon strain, Salmonella Saintpaul: red plum, red Roma, and round red.

Because of their early harvest dates and widespread distribution, growing areas and processing plants in South Florida and Mexico have been under closest scrutiny. However, the first and by far the largest number of reported cases occurred in New Mexico and Texas from tomatoes harvested in April from as yet an unknown source.

Meanwhile, the FDA is clearing tomatoes as safe if they come from growing regions and states where tomatoes have not yet ripened, or were not ripe at the time the cases were first reported.

At present, FDA is withholding information about the location of a cluster of nine cases, since such information is considered part of the “ongoing investigation,” and “commercial confidential.”

Even though the FDA and CDC have not been able to “trace back” the source of the contamination, Dr. David Acheson, FDA’s associate commissioner for foods, says the probability of the same genetic type of Salmonella coming from more than one geographic location is “highly unlikely.”

How does contamination occur?

In its 40-page “Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables,” the FDA outlines contamination hazards and methods to reduce risk. For example, contamination with human or animal feces may occur as the result of physical contact with runoff water near feedlots, overflowing manure lagoons, contaminated irrigation water containing raw sewage, improperly treated effluents from sewage treatment plants or inadequate farm worker toilet and sanitation facilities.

Of particular interest are recent studies showing that produce can take up pathogenic bacteria via their root systems, as well as through flesh or stem scars.

For example, during processing in order to help keep the fruit “fresh,” hot tomatoes may be placed in large vats of cool water, called hydrocoolers. According to FDA’s Acheson, the temperature gradient can cause the cool water to “get sucked inside the tomato.” If that water is contaminated with Salmonella, many tomatoes can become contaminated, and routine washing at home will not effectively remove the internalized bacteria.

Safe in my backyard

Even though we’ve known about Salmonella bacteria for over 100 years, widespread outbreaks are a modern day dilemma of centralized food systems.

Jennifer Wilkins, a Cornell nutritionist who examined the recent food-borne illnesses associated with spinach and lettuce, says it’s unwise to "take all of our salad from the same bowl." In other words, food production that occurs on a single or handful of farms and facilities, and then serves the entire nation creates potential widespread public health risk.

"Smaller, more localized production and processing systems are not immune to contamination," Wilkins says. But if problems do arise, "they’re less costly, far easier to trace and have less widespread consequences."

Local, organic, tasty and less likely to carry Salmonella.

Ka-ching

Speaking of costs, ever wonder about the price tag on a nationwide outbreak? No Federal agency is keeping tabs on the total costs of this and other food-related outbreaks. But outside of retail losses, calculating the true costs would have to include: loss of income to farmers; health-care costs and lost employment of those sickened by Salmonella; lab fees, salaries and travel of FDA and CDC staff; and, lost energy and fossil fuel costs associated with growing, harvesting, processing, packaging, shipping, and now disposing of the fruit.

Unfortunately, the FDA’s guide, which addresses “Good Agricultural Practices” (GAP) to ensure produce safety and protect public health, offers voluntary guidance, not regulation. The FDA has requested greater regulatory authority around preventive controls for high-risk foods. However, Florida couldn’t wait for stricter national mandatory rules. In response to the economic devastation brought on by prior Salmonella-tomato outbreaks, the Sunshine state is adopting the GAP as a state regulation beginning July 1, 2008.

Keep it simple…

To help protect public health, the FDA advises simple consumer messages:

• Grape and cherry tomatoes, as well as tomatoes sold with vines attached are safe to eat, since they have not been implicated in any of the outbreak cases.
• All tomatoes are considered safe to eat if they come from one of the states or regions cleared by FDA: www.fda.gov/oc/opacom/hottopics/tomatoes.html
• Avoid eating tomatoes with broken or split skins, or signs of decay.
• Wash tomatoes under running water, not in a sink or tub; detergent or special rinses not necessary.
• Refrigerate tomatoes after you’ve cut or sliced into them.
• Wash hands after handling pets, changing diapers, using the bathroom and before preparing food.
• Wash cutting boards, dishes, utensils and countertops with hot water and soap.
• Know the source of your food. The FDA says: “If consumers are unable to determine the source of their tomatoes, they should not be eaten.”
• Backyard tomatoes are safe! Handle them carefully, and enjoy.

Two tomatoes

The latest food safety fiasco boils down to two choices. One tomato is available year-round, harvested by unfamiliar hands (or machines) and passed through multiple potential contamination points before reaching unwitting consumers. The second, a tantalizing, local, organic tomato, drips with fresh flavor and carries a bounty of nutrients that only develop on the vine. It requires patience. But some things are simply worth waiting for.

Melinda Hemmelgarn, M.S., R.D., is a registered dietitian, advocate for sustainable food systems, and Food and Society Policy Fellow. She’s based in Columbia, MO.

References:

Salmonella outbreak: Centers for Disease Control and Prevention: www.cdc.gov/salmonella/saintpaul/

Food and Drug Administration: www.fda.gov

Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables: www.cfsan.fda.gov/~dms/prodguid.html

Plant root uptake of pathogens: http://barfblog.foodsafety.ksu.edu

FDA Press calls: 6/11/08; 6/12/08; 6/13/08; 6/16/08; 6/17/08

USDA Economic Research Service: www.ers.usda.gov/Briefing/Vegetables/tomatoes.htm