Do You Know Where Germs Lurk?

I’m currently suffering my second cold of the spring and summer. Maybe that’s why a recent survey on germs caught my eye. It seems most people have a skewed perception of where germs really lurk in the environment. Since 80 percent of infectious diseases are spread through hand contact, that means many people may not take the best possible precautions.

The survey, conducted by a polling firm on behalf of Dr. Charles Gerba, a professor at the University of Arizona and so well-known an expert on environmental microbiology that his nickname is “Dr. Germ,” was given over the phone to 1,000 representative adults, aged 18 and older. The results had a margin of error of plus or minus 3.1 percent.

In the first question, people were asked which of a list of common household items has the most germs. The largest number picked the dishrag, followed by garbage can, toilet bowl, bathroom doorknob, refrigerator and kitchen sink, in that order.

And, indeed, other studies by “Dr. Germ” have shown that the dishrag is the germiest of the items listed--but the kitchen sink, dead last in the survey, is in fact the second-germiest, followed by the toilet bowl, garbage can, refrigerator and bathroom doorknob. The dishrag and kitchen sink both rank high because both are moist so much of the time. In a follow-up question, half those surveyed guessed incorrectly that the toilet seat is germier than the kitchen sink; in fact, the kitchen sink is germier.

Next, people were asked to pick the germiest in a list of workplace items: phone receiver, toilet seat, elevator button, keyboard and desktop. Again, the largest number picked the phone receiver as germiest, which is correct; but after that came toilet seat, elevator button, keyboard and desktop. In fact, the desktop is the second-germiest item in the workplace behind the phone receiver. The keyboard is third, the elevator button is fourth, and the toilet seat is actually the cleanest thing of all.

To be precise, Dr. Gerba’s study of workplace germs a couple of years ago showed an average of 25,127 bacteria per square inch on the phone receiver, 20,961 per square inch on the desktop, 3,295 per square inch on the keyboard, and only 49 per square inch on the toilet seat. Dr. Gerba estimated that on the typical desktop the area where you rest your hand has about 10 million bacteria in total.

The difference? Toilet seats are cleaned with disinfectant more often than desktops and keyboards. So while you probably wouldn’t think twice about eating off your desk, you’d actually be better off, scientifically speaking, eating off the toilet seat--although you’d find it harder to explain to your co-workers.

Next, people were given a similar list of public items, including picnic tables, amusement park turnstiles, playground equipment, escalator handrails, shopping cart handles and Port-o-Potties. Not surprisingly, the most popular choice for germiest public item was the Port-o-Potty, shopping cart handles were second, escalator handrails third, playground equipment fourth and amusement park turnstiles and picnic tables tied for fifth.

This one was almost completely upside down. The cleanest thing on that list is actually the Port-o-Potty, while the germiest is playground equipment. Escalator handrails are second-germiest, shopping cart handles third, and picnic tables fourth. (There’s no data on amusement park turnstiles.) Again, the big difference is that (most) Port-o-Potties actually get cleaned on a semi-regular basis; nobody ever cleans playground equipment.

Other questions asked people to choose which of two items is the germiest. Among the mistaken ideas: 64 percent guessed that a public restroom doorknob has more germs than an ATM, when in fact, the ATM has more--probably because more of the hands that touch a public restroom doorknob have just been washed than the hands that touch an ATM.

Almost everyone surveyed claimed that they always or most of the time wash their hands after using the bathroom; three in four said that they wash their hands before eating in a restaurant. Just over half said they wash their hands after coming in from outside, or after sneezing or coughing. But only one in three said they wash their hands after using public transportation, and only one in five said they wash their hands after shaking hands.

Women were significantly more likely than men to report washing their hands in all of the above situations.

You can’t escape germs completely, but you can take some basic precautions that might save you from (ahchoo!--pardon me) the ravages of a (sniffle) miserable summer cold (cough).

For me, alas, it’s too late.

These weekly columns on science appear in the Regina (Saskatchewan) Leader Post and Red Deer (Alberta) Advocate.  They are available for one-time publication or regular syndication to any interested newspapers, magazines or on-line publications.  E-mail me for details.