The serious dirt on produce is not the kind you can see.

Those ready-to-eat bags of spinach, lettuce and mixed greens in grocery stores may boast that they've been "thoroughly" or "triple" washed, but that's no guarantee they're free of nasty bacteria.

Washing it yourself may add risk, because bacteria on hands, utensils or in the sink could contaminate the already washed produce.

As fresh spinach returns to supermarkets, the unsolved E. coli outbreak that spread to 26 states has forced many consumers to reconsider the safety of packaged greens — and how little they can do about it.

The $4 billion packaged lettuce and spinach industry has safety measures. But the standard process — washing lettuce and spinach with chlorinated water — kills 90 percent to 99 percent of microbes, which include bacteria. And that's only if the process is done well, which government inspection records show is not always the case.

"People think it removes everything, but it doesn't," says Jack Guzewich of the Food and Drug Administration's food safety center.

Growers and processors pointed out their triple-wash procedures when the outbreak became a national news story Sept. 15. Product was recalled, and consumers were warned to abstain from fresh spinach.

What was largely left unsaid was that the triple washing of greens in the factory is intended to help prevent bacteria from spreading and "NOT to surface sanitize produce," says an April industry report, Commodity Specific Food Safety Guidelines for the Lettuce and Leafy Greens Supply Chain.

In fact, there's no "effective kill step" for leafy greens that would not damage them so much that they'd no longer be fresh, says Trevor Suslow, research specialist at the University of California, Davis. When juice and milk are pasteurized, generally 99.999 percent of contaminants are killed.

Leafy greens have to be handled more delicately, and chlorinated-water washes have long been the preferred method.

"Once the product is inside the (factory), it is the most important step to minimize risk," says Wil Sumner, director of food and agriculture testing for Scientific Certification Systems of Emeryville, Calif., which audits company practices and certifies product. Simply washing produce with regular water only removes 60 percent to 90 percent of microbes, Sumner says.

But produce companies vary in how well they wash. "Some companies are right on top of it. Others are not so much," the FDA's Guzewich says.

From 1998 through 2004, the FDA inspected 36 domestic and foreign produce farms, including packing sheds where produce was washed and packed. The FDA found 12 instances in which chlorination measures fell short — including lack of chlorine, inadequate amounts, no monitoring of levels and at least one instance in which workers didn't understand the measurements, Guzewich says.

FALSE EXPECTATIONS

Federal regulations require food processors to follow good manufacturing practices to minimize contamination. But regulators issue only general guidance to companies on how to do that.

In general, chlorine levels in wash water should rise with the amount of produce being handled, Sumner says. They are far higher than chlorine levels in regular tap or pool water. Organic producers use chlorinated water, too, although sometimes at lower concentrations. Monitoring is also left to the company.

Also, the industry continues to battle expectations that triple washing catches all bacteria. The industry is continually educating growers and others that they "can't count on that step (triple wash) as a pasteurization step," says David Gombas of the United Fresh Produce Association. "We don't want to set up any false expectations that they can relax and expect the washing to take care of it."

For three weeks, state and federal inspectors have swarmed over farms and companies in the Salinas Valley in California, looking for the source of the deadly E. coli O157:H7 strain tied to 193 infections, including one death, in 26 states and Canada.

Last month, the FDA said consumers can again eat fresh spinach as long as it isn't involved in the recall. It traced all the implicated spinach to a major processor, Natural Selection Foods of San Juan Bautista, Calif. Natural Selection recalled its spinach products. The investigation continues into where and how the outbreak started.

FROM SEED TO SINK

Since 1995, lettuce or spinach has been associated with 20 E. coli outbreaks, the FDA says. The last nine outbreaks involved packaged product, which accounts for 80 percent of the $4.4 billion American consumers spent in the past year on lettuce and spinach, says The Perishables Group, a market research firm. Packaged lettuce was the far biggest seller: $3.2 billion.

The industry also maintains that the packaged product is safe to eat straight from the bag. "There is no kill step, but we have many food safety practices in place," says Tanios Viviani, president of Fresh Express, the leading packaged salad maker.

He says Fresh Express reviews everything from the quality of seed, to the fertilizer, to how far cattle — a source of E. coli — are from fields. "Triple wash is just one of the steps," he says.

Other processors, including Dole Foods, which says it pioneered the triple wash procedure, refused interviews because of the ongoing E. coli investigation.

Gombas, of the produce association, says there may be more reports of E. coli outbreaks in packaged versus unpackaged lettuce and spinach because packaged products are more popular and are more widely distributed. A head of lettuce most likely would be eaten by one household, and if contaminated with E. coli, the incident may go unreported or unnoticed, he says. If that same head of lettuce was chopped up and put into bags, pieces may get into several households and make an outbreak more noticeable, he says.

BAGGED 'IS SAFER'

While Doyle won't eat packaged lettuce or spinach, Christine Bruhn, director of the Center for Consumer Research at the University of California, Davis, says "the bagged product is safer" than its home-washed, unpackaged counterpart.

Given previous E. coli outbreaks in lettuce, California officials earlier this year convened a panel of food safety and industry experts to re-evaluate whether packaged lettuce and leafy greens should be rewashed before being eaten.

The panel decided no, as long as the product was labeled "washed," "triple washed" or "ready-to-eat" and came from a government-inspected facility.

Bruhn, a panel member, says rewashing may increase risk because consumers are unlikely to sanitize hands, nails, sinks and utensils.

While no produce is guaranteed 100 percent free of bacteria, cooked, canned or frozen produce comes closer than raw, Bruhn says. If you eat raw lettuce or spinach, you take a risk, she adds. "But it is a small risk. The industry does a superb job of washing."

ENJOY SPINACH BY GROWING YOUR OWN

Fresh spinach. So delicious tossed with a raspberry vinaigrette or sauteed with a little olive oil.

Still leery about buying packaged spinach? If you have some space in your yard, or even a container, you can grow your own.

Start spinach seeds indoors with a seed-germination mat, available at nurseries. Place the mat in a sunny window. The spinach will sprout in five to 10 days. When the plants have five leaves, they are ready to be transplanted into the ground or a container. The plants should reach maturity in about six weeks.

IF PLANTING IN THE GROUND ...

1. Choose a site that gets full sun.

2. Work plenty of organic compost into the soil.

3. Plant seedlings 6 inches apart in wide rows.

4. Keep the soil moist. Feed the plants fish emulsion (available at nurseries) every 10 days until they are 6 inches tall. Mary Meador, store manager of Soil Service Garden Center in Kansas City, also recommends a product called Bioform Dry, an organic fertilizer made of chicken manure, fish and 1 percent sulfur.

5. Once plants are established, mulch the bed to deter weeds.

6. Harvest spinach leaves as needed from the outside of the plant.

IF PLANTING IN A CONTAINER ...

1. Use a potting mix instead of topsoil. A 6-inch diameter pot is roomy enough for three seedlings.

2. Place the container in a sunny spot outdoors.

3. Keep the soil moist.

4. Fertilize with liquid fish emulsion. "Solid fertilizer is not so good for containers," Meador said.

Source: ehow.com

— By Julie Rehm, McClatchy-Tribune News Service