How dirty is your money? Do employees transfer bacteria by hand to food after handling coins and cash?
In January, answers to these intriguing questions spread faster than a virus, from weekly newspapers in America's heartland to international infection and food industry associations, triggered by an article carried via wire services and worldwide list serves.
What's old is news again. The story summarizes research published in 1999 in the International Association for Food Protection's Journal of Food Protection.
But that date wasn't mentioned in the article sent to newspapers and newsletters by cooperative extension agents including Sheila Craig, a county educator in Rushford, Minn. She says she got the information last year in a packet from her state specialist, who got the information from a Kansas State University newsletter last summer.
It would take someone with a lot of time on their hands to track where it came from before that, or where it will go next.
"The first time that research came out, it became almost an urban legend," said Fred Reimers, food safety manager at H-E-B Grocery Co., San Antonio, Texas, the country's largest private grocery chain. "In the food industry, there are much greater chances for contamination, but people point it out because they see it happen. Companies don't want a bad name because of it."
There's no question that currency is contaminated with a variety of noxious and deadly organisms. A 1972 Journal of the American Medical Association study found that 70 percent of U.S. currency was contaminated by bacteria, and that 13 percent of coins and 42 percent of bills carried pathogens including Staphlococcus aureus, Escherichia coli and Pseudomonas aeruginosa. A 1999 University of California at San Francisco study found 18 percent of coins and 7 percent of bills sampled were contaminated with S. aureus, Klebsiella, Enterobacter, and E. coli. Other studies have found similar levels of these pathogens and others including a-hemolytic Streptococcus, Corynebacterium, Vibrio and Enterococcus.
The 1999 report was designed to determine the likelihood of coins serving as the vehicles to transmit two major food-borne pathogens from hands to food.
Further, only a low dose of either is required to cause human infection.
"The Fate of Escherichia coli O157:H7 and Salmonella enteritidis on Currency" was written by researcher Xiuping Jiang and Michael P. Doyle, Ph.D., professor of food microbiology and director of the Center for Food Safety and Quality Enhancement at the Department of Food Sciences and Technology at the University of Georgia in Griffin.
They isolated five strains of human and animal isolates of E. coli O157:H7, and five strains of human and food isolates of S. enteritidis. The coins, all minted after 1990 and in good condition, were washed, autoclaved and sterilized before they were inoculated with the pathogens. After they dried, they were stored at 25 degrees C, 40 percent relative humidity (conditions approximating a typical cash register) in a controlled environmental chamber. Each day, individual coins were removed and tested. No coins were replaced or reused.
S. enteritidis survived for one, two, four and nine days on the surfaces of pennies, nickels, quarters and dimes, respectively.
E. coli O157:H7 survived for seven, nine and eleven days on the surfaces of pennies, nickels and both dimes and quarters, respectively.
The authors suspect high copper content caused the differences in bacterial survival on coins. They also found that bacteria survived longer on coins than on glass and Teflon surfaces they tested simultaneously, and attributed the difference to coins' irregular surfaces.
"Both Escherichia coli O157:H7 and Salmonella enteritidis can survive in a dried state on coin surfaces for several days at room temperature. Hence, it appears that coins could serve as vehicles for transmitting these two pathogens," they concluded. "Food handlers should use an intervention treatment such as washing hands after handling coins and before handling foods."
When discussions flare up periodically in the food protection industry, the consensus is that the issue is "more perception than a major contaminant," said Reimers, and there's been little follow-up research.
Regardless of how far the story spreads, food industry employees' hands can rock the customers' confidence. Employees need reminders to keep their hands clean—and use gloves appropriately.
After removing a glove to handle money, discard it, don't reuse it, said Reimers. "Gloves are for single use. Contamination and overuse become a greater risk," he said, since snapping them off and on can spray a gloveful of perspiration and organisms onto nearby food.
Now, that's enough to make you sick.
Wendy L. Bonifazi, R.N., APR, covers health and medicine from Fort Collins, Colo.
Natural Foods Merchandiser volume XXIII/number 3/p. 36