Can You Trust Your 'Yuck' Reflex?

Yuck!

Rotten eggs, an overflowing toilet, sewer stench -- can you feel your nose crinkle? Good, says Miryam Z. Wahrman, a biology professor at William Paterson University in Wayne, New Jersey, and author of "The Hand Book: Surviving in a Germ-Filled World." That "yuck factor," as she calls it, "can influence behavior, and it can encourage us to make healthy choices," she says. Case in point: When cigarette boxes became canvases for repulsive photos, a significant number of people stopped smoking. (Likewise, you throw out the eggs, choose a different stall and cross the street.) But your yuck factor isn't always so reliable. Here are seven everyday items whose germiness level may surprise you:

1. Your cellphone

It's your alarm clock, calendar, GPS, social lifeline and news source. It's also replete with germs, Wahrman says. "A cellphone is such a personal object that when you borrow somebody's cellphone, you're really sharing a lot of germs," she says. Even if you keep it to yourself, clean it regularly with alcohol wipes -- especially if you carry it between the bathroom and, say, the lunchroom, Wahrman suggests. Hospital workers need to be particularly vigilant about washing their hands between using phones and touching patients in order to avoid hospital-associated infections. "That's a potentially deadly scenario," Wahrman says.

2. Your commute

Listen up, city-dwellers: Many of your fellow passengers on public transportation are invisible. The New York subway system, for instance, is home to 1,688 different life forms, nearly 50 percent of which aren't identifiable, one study showed. "This is good news for biologists, who will not be running out of research subjects anytime soon," Wahrman quips in her book. While only 12 percent of the bacteria found are disease-causing, 57 percent have the potential to cause disease in people with weakened immune systems, such as babies and older adults. And most of the bacteria matched those found on human skin, in the gut and in the urogenital tract. Can we get a "Yuck?"

3. Your office

From your chair to your phone to your computer mouse, your workplace is an environment ripe for germs. One study, for example, found more than 500 different types of bacteria in New York, San Francisco and Tucson, Arizona, offices, mostly from people's skin, nose, mouth and -- wait for it -- intestinal cavities. Male-dominated offices and spaces were especially germy, perhaps because men wash their hands less or because they're bigger and therefore shed more bacteria. One simple fix, besides washing your hands frequently? Buy a keyboard cover, suggests Melissa Hawkins, director of American University's Public Health Scholars Program. "They are inexpensive, easy to clean and wipe down," she says. "They also add a layer of protection against spills."

4. Your money -- even if it's plastic

Craving a street taco, gyro or old-fashioned hot dog for lunch? Don't put your money where your mouth is. Wahrman and colleagues found that food cart workers appropriately changed gloves only seven times in 500 transactions. "That should give you pause about where you want to eat," she says. While cash is understandably germy, given the countless hands it's touched, even using a credit card at a sit-down restaurant won't fully protect you: ATM touchpads, credit card machine styluses and restaurant menus make Wahrman's list of most germ-laden public surfaces. But you don't have to starve if you want to eat out. "It's really a matter of just knowing where your hands have been and then acting accordingly," Wahrman says. Translation: Wash your hands.

5. Your (healthy-looking) colleague

Despite Wahrman's mother's death from a hospital-acquired infection and her passion for germs, which inspired her to write a book about protecting ourselves from them, she'll still shake your hand. "It's just something we can't avoid," she says. However, it's important to follow schmoozing with soaping -- even if your colleague didn't just sneeze. "Infectious people can look very healthy and they can be incubating disease," Wahrman says. Just take it from Dr. Bill Schaffner, an infectious disease specialist at Vanderbilt University School of Medicine, who keeps hand sanitizer in his pocket. "At the infectious disease meetings," he says, "everybody thinks that's normal."

6. The grocery store

Some supermarkets have those sanitizing wipes for good reason, inviting you to wipe down your cart handle -- aka germ heaven, Schaffner says. "I'm delighted that over the past eight to 10 years, the widespread use of hand-hygiene gels and liquids has become so common," says Schaffner, a former member of the Infectious Diseases Society of America's executive committee. But those products aren't meant for another problematic item: the plastic wrap around raw meat, which can be contaminated and lead to food poisoning. Since kids' hands often wind up in their mouths, he says, "Keep those raw meat and raw chicken packages away from your youngsters whilst you're shopping."

7. Your kitchen

Just because you're home doesn't mean you're home free. "If you don't share cups and utensils between children and between yourself, then you're going to reduce the risk [of infection]," Wahrman says. It's also important to clean cutting boards (whose porous surfaces attract bacteria) after each use, run sponges (which also harbor bacteria) through the dishwasher weekly and avoid rinsing raw meat in the sink, Hawkins adds. "Many recipes still call for rinsing chicken as the first step, but modern food-safety science has demonstrated that this is not necessary," she says.

Hand-washing 101

The list goes on: doorknobs, faucets, playground swings, gym equipment, escalators. "If you look hard enough, you'll find a germ here or there on almost any inanimate object," Schaffner says. But most aren't concerning -- even toilet seats and hotel blankets, for instance, won't hurt you. (Airlines that wrap blankets in plastic do it for public relations -- not public health, he says.) What's important is washing your hands regularly for at least 20 seconds with soap and warm water -- and drying them with a towel rather than a warm air dryer, which actually increases the bacterial count on your hands, research shows. "When in doubt," Wahrman writes, "wash your hands."