Part of larger crackdown

EPA’s order that Joyce Chen Inc. "cease and desist" its sale of these cutting boards is just the latest in a string of related actions. On May 28, EPA’s Chicago-area enforcement division reached a settlement with Ecko Housewares Inc. of Franklin Park, Ill. The company agreed to pay a $100,000 fine and cease antibacterial claims for a wide range of products -- including brushes, sponges, and cutting boards -- whose plastic contained a "Germ Away" formulation, Mosley says.

Like the Joyce Chen products, Ecko had made unsubstantiated pesticidal health claims for these housewares, she notes.

So did the 3M Corp. in its advertising for O-cello sponges, which also contain an allegedly antibacterial agent embedded directly into the product. On March 7, EPA ordered the company to cease the sale of these products. Eleven days later, the regulatory agency amended its order, saying the company could continue selling the sponges if it covered over or removed any antibacterial health claims on the product labels and advertising. However, notes Jerry Stubbs, a branch chief with EPA’s Toxics and Pesticides Enforcement Division, the 3M case remains "an open investigation."

This issue of improper antibacterial health claims also triggered EPA’s moves against the Pawtucket, R.I.-based Hasbro Inc., maker of Playskool toys. On April 22, the agency entered a settlement with the company. In addition to paying a $120,000 fine, Hasbro must cease to make any health claims about its nine toys whose plastic surfaces had been embedded with Microban, a bacteriostatic compound.

Like zinc oxide, Microban has been legally used in other products to prevent the growth of certain bacteria, Mosley notes. However, she points out, in each of those products, the antibacterial agents were used to protect the product -- not the health of the product’s user.

It’s a critical distinction, she notes, because pesticides can win an exemption from FIFRA if they are present only to protect a product -- such as to keep down the growth of mildew in the plastic used in lawn chairs or to prevent the buildup of odor-causing bacteria in clothes.

The EPA regulators' recent activity is a response to escalating consumer fears about the home as a reservoir of infectious germs. The General Accounting Office estimates that as many as 81 million cases of foodborne illness occur in the United States each year, racking up health care costs in excess of $5 billion.

Though few studies have attempted to tally how many of these cases trace to food prepared at home (versus restaurants), microbiologist Elizabeth Scott of Newton, Mass., has made several stabs at estimating the share attributable to home-cooked food in her native Britain and several European countries, where much more detailed national records on cases of food poisoning are available. Those analyses conclude that the vast majority of these gut-wrenching infections stemmed from contamination in the home.

Kitchen science or common sense?

The EPA actions are sure to rekindle a long-simmering debate among home economists on the relative safety of wood versus plastic for cutting boards and other surfaces that come into contact with food. While many cooks prefer the look and feel of hardwood, the Food and Drug Administration has long recommended using only plastic (SN: 2/6/93, p. 84), arguing that while germs can be washed off plastic, wood’s micropores offer ideal hiding places for bacteria to evade eviction during a soap-and-water cleansing.

Yet when Charles E. Benson, a microbiologist at the University of Pennsylvania School of Veterinary Medicine in Kennett Square began probing the basis of such recommendations, he was surprised to find that "little of it was based on research." Instead, he found, these prescriptions usually constituted "suggestions based on no concrete evidence that something really works."

It’s a problem that used to frustrate Ban Mishu Allos when he worked in the foodborne pathogens section at the Centers for Disease Control and Prevention in Atlanta.

"People would call CDC asking us if it was better to use a wooden or plastic cutting board," she recalls. "And the answer that we’d always give was that there are no data." When pressed, she would say, "if you’re more comfortable using a plastic board, because it seems logical that it ought to be more sterile, fine. But there’s no hard data proving that’s the case."

Scott notes that what people term "common sense is really more tradition. A lot of it doesn’t seem to be supported by anything."

For instance, she notes, "so-called experts from this university or that one are always saying wash your dish cloth and sponge in soap and hot water. Or wash your countertop and cutting board with soap and water. But that isn’t really enough," her data show, "because this doesn’t kill the bacteria. In fact, it often causes you to spread the contamination."

In one study that she performed while still in England, she applied a detergent and water to a counter top and then scrubbed. "Afterwards," she found, "there were more bacteria than when you started." The reason: Most damp sponges, sitting near the sink, contain millions of bacteria. By adding the detergent, she found, you break up the bacterial colonies and spread them around."

When Dean O. Cliver of the University of California-Davis began testing that common-sense wisdom as it pertains to cutting boards, 4 years ago, he too found that it didn’t seem to hold up. Microbiologically, at least, wood outperformed plastic, because he could extract plenty of live bacteria from the surfaces of plastic boards but virtually none from wood boards that had initially been tainted with the same number of bugs (SN: 2/6/93, p. 84).

In follow-up tests, he’s witnessed the same trend. Even after slathering bacteria onto wood cutting boards, he finds it next to impossible to retrieve them because they are quickly drawn beneath the surface into the initial 1 millimeter of wood (see Sponges and sinks and rags, oh my!).

Though many bacteria die during this process, some can remain alive for hours. However, even they can’t contaminate food unless the boards are cut open, he’s found. "And from that standpoint," he told Science News Online, "our results are reassuring."

Yet even he wouldn’t trust his wood cutting boards to fully decontaminate themselves. He washes them thoroughly -- and, when in doubt, microwaves them for a deep steam cleaning. His team published its experimental findings on how procedures for using a microwave to clean hardwood boards last year in the Journal of Food Protection, and equivalent data for dishrags or sponges, this year, in a journal serving the commercial food-service industry.

Tailor cleanup to the surface

The studies by Cliver’s team at the University of California-Davis indicate that plastic boards retain large quantities of disease-causing germs at the surface -- and that those bugs tenaciously resist removal by hand washing. While you can’t microwave plastic surfaces clean (they don’t heat up enough to roast the bugs), a hot dishwasher cycle dislodges or kills microbial squatters, he and others have shown.

Don’t forget stainless steel surfaces -- kitchen pans, knives, sink, food- processor blades, and mixing bowls. "A couple of studies that I did with some high school students showed that what looks clean is not necessarily clean," notes Benson. These metal kitchen wares emerged from a standard hand washing bearing residues of food and bacteria. These science-fair studies, which weren’t quantitative and didn’t culture specific strains of bacteria, met the students’ needs. "But we’d like to take it further now and give it some good documentation," Benson says.

Even hand-washed stainless steel can harbor germs, as seen here. Pseudomonas bacteria (dyed pink) has attached via thin filaments to take up residence amid a field of microscopic food particles (dyed yellow). Credit: E.A. Zottola, Univ. of Minn.

Though most of the utensils they surveyed did emerge "relatively clean" from a dish washing machine, Benson worries about the water that often sits on the bottom of the dishwasher between washings. "I’d hate to think of it as a growth medium for these bugs," he says. It’s another issue he’d like to investigate.

To be safe, Edmund A. Zottola of the University of Minnesota recommends washing metal with soap, to break up those bacterial colonies, then rubbing the utensils vigorously. He follows this up with a sanitizing rinse of dilute bleach.

That may be suitable for commercial kitchens, but Susan Sumner, a food scientist at Virginia Polytechnic Institute and State University, has developed a less toxic alternative for home use that may also prove more versatile. She sprays contaminated surfaces with a mist of vinegar and then a mist of hydrogen peroxide. The disinfectant combo kills bacteria on not only metal, plastic, and wood, but also on foods, such as meat and lettuce leaves (see How to disinfect your salad).