by Charles John Palenik
Charles P. Gerba, PhD, professor of environmental microbiology at the University of Arizona, is an expert on drinking water quality and pathogens in the environment. He has published more than 400 scientific articles and nine books. He developed the first method to test water for the presence of cryptosporidium, a parasite responsible for sporadic outbreaks of diarrhea. But it is his interest in household and workplace microbes that has brought him greater recognition and the moniker — Dr. Germ. For Dr. Gerba, it all started after flushing a toilet in Houston, Texas.
While a postdoctoral fellow at Baylor University, Dr. Gerba was asked by his advisor to observe a toilet flushing and to note the aerosols generated. Dr. Gerba soon devised a method for studying the distribution patterns of the droplets emitted, and called it a “commodograph.” Analyses of emissions indicated the presence of high numbers of bacteria and viruses. Microorganisms form biofilms on porcelain surfaces with gradual elution after each flush. The study indicated the presence of fecal organisms on a variety of bathroom surfaces. Air currents moved aerosolized microbes to surrounding areas unless they were blocked by a door. Flushing with the lid down also reduced microbial spread. Dr. Gerba advocated placing toothbrushes within drawers or in the medicine cabinet to prevent contamination.
Few things strike more fear than toilet seats in public restrooms. But are toilet seats truly evil menaces?
Studies performed by Dr. Gerba indicate that toilet seats and door handles are actually the cleanest surfaces in public restrooms, perhaps because they are the two surfaces people avoid touching. The floor was by far the dirtiest, having more than two million bacteria per square inch. Sanitary napkin disposal units were also heavily contaminated. Sinks did not fare well either. Most people seek privacy and tend to use the stalls at the rear of the restroom so fewer bacteria were present in the first stall. Study results indicated fecal bacteria were present on the bottoms of more than 30 percent of women’s purses. Placing a purse on the floor appears to be risky business. Dr. Gerba concluded that contamination of hands is more likely during a restroom visit than is contamination of bottoms. He advocates proper hand hygiene but without the use of hand dryers. Dryers use restroom air and blow suspended microorganisms over your hands. You may actually end up with dirtier hands than when you started.
Dr. Gerba thinks that the concern about restrooms and toilet seats may be somewhat misplaced. In his estimation, household areas outside the bathroom and many surfaces within the workplace are far more contaminated.
According to Dr. Gerba, the kitchen is the most germy place in the home. The worst offender is the kitchen sponge or dishcloth, followed by the sink, the cutting board, and the floor. Preparation of animal protein products plus contaminated fresh fruits and vegetables are the major culprits. Most foodborne illnesses originate in the home.
Dr. Gerba has also extensively studied microbes in the workplace. He found the most contaminated surfaces were phones, desktops, water fountain handles, microwave door handles, and keyboards. On average, desktops had 400 times more bacteria than did toilet seats in the same office.
Most people consider their desk their private space, often covering it with photos and mementos. Cosmetics are commonly present. Gerba found that munchies were present in 75 percent of women’s desks. Men and women frequently ate and drank at their desks. Young children often visited the offices/desks of women rather than men.
Desk areas that were frequently touched contained, on average, 10 million bacteria. Offices have almost 21,000 microbes per square inch. The two most contaminated surfaces for men were wallets and palm pilots. Dr. Gerba found mold on office surfaces, most commonly in the bottom desk drawer — a popular place for stashing lunch and snack foods. A 2006 American Dietician Association survey reported 57 percent of workers snack at least once a day at their desks. More than 75 percent “only occasionally” clean their desks before eating while 20 percent said they never do.
Dr. Gerba offers some simple, straightforward advice on how to combat workplace microorganisms. This includes:
- use a disinfectant wipe on phones, desktops, keyboards, and other contaminated surfaces once a week
- use a hand sanitizer throughout the day
- avoid eating at your desk on a regular basis
- wash coffee mugs and glasses regularly
- install and use a dishwashing machine
- if you are sick, do not go to work
According to Dr. Gerba, following these tips could potentially reduce absenteeism by 50 percent. This figure would be higher for workers with families since parents tend to stay home when their children are ill.
Dr. Charles John Palenik is the director of Infection Control Research and Services at the Indiana University School of Dentistry. He is the co-author of the popular “Infection Control and Management of Hazardous Materials for the Dental Team.” In 2003, he was chairman of the Executive Board of OSAP. Infection control questions may be directed to [email protected].