How Concerned Should We Be about Computers and Phones as Disease Vectors?

An Associated Press feature on Friday, Filthy Stories from the Office, noted that computer keyboards, cellphones, the buttons on office printers and photocopiers, and other office and home office surfaces harbor "a rank stew of vile bacteria" with "hundreds of times more bacteria than a toilet seat", citing a statistical metric that has become a bit of a cliché.

The article references the research of the findings of America's leading expert on work and home hygiene, Charles Gerba, a professor of microbiology at the University of Arizona, and other experts in the field.

A recently posted Apple Knowledge Base article, How to Disinfect the Apple Internal or External Keyboard, Trackpad, and Mouse, says:

"In addition to regular cleaning of your computer and input devices (keyboards, trackpads, and mice), you may find it necessary to disinfect them.

"Multiple people using the same computer, people using the computer when they were ill, and the particular environment where the computer is used, are a few reasons you may wish to disinfect areas of the computer that people come into contact with the most.

"In order to properly disinfect these areas, you should use Lysol Wipes, Clorox Disinfecting wipes, or Clorox Kitchen Disinfecting Wipes . . . when disinfecting your Apple product."

Several of Dr. Gerba's studies conducted at the University of Arizona have found that telephones are the most germ-infected objects in usual environment, followed by desktops, water fountain handles, microwave door handles, computer keyboards and mice. (Famously, these studies have found that keyboards generally have 400 times more bacteria than an average toilet seat.)

Here are the relative germ densities of frequently touched office equipment cited in the study abstracts:

• Phone: 25,127 germs per square inch
• Desktop surface: 20,961 germs per square inch
• Keyboard: 3,295 germs per square inch
• Mouse: 1,676 germs per square inch
• Fax machine: 301 germs per square inch
• Copy machine: 69 germs per square inch
• Toilet seat: 49 germs per square inch.

The area where you rest your hand on your desk has on average 10 million bacteria, say the researchers.

"For bacteria, a desk is really the laptop of luxury," Dr. Gerba commented in a press release. "They can feast all day from breakfast to lunch and even dinner." Gerba and his researchers found that unless desks were wiped clean with a disinfectant during the day, bacteria levels climbed higher and higher, peaking after lunch.

The bacteria crawling all over your phone, keyboard, and mouse may include hundreds of different types, including E. coli, Klebsiella pneumonia, streptococcus, salmonella, and staphyloccus aureus (a.k.a. "staph").

But is this something to be concerned about?

IMHO, it's unwise to be too flippant about exposure to potentially pathogenic germs. Being sick is no fun at all, and exposure to microbes can make us sick. On the other hand, becoming obsessively paranoid about it is no doubt counterproductive. Millions of people inhabit office environments and seem to survive reasonably well, and it's arguable that some anti-germ countermeasures may actually be playing a part in making the problem worse - for example, use of antibacterial agents actually promote the development of antibiotic-resistant so-called "superbugs."

For example, according to Dean Oliver, a professor of food safety at the University of California cited in the AP piece, washing your hands for 20 seconds under soap and running water is preferable to a squirt of hand sanitizer at your desk, and even though many hand sanitizers contain anti-microbial chemicals, scrubbing with ordinary soap is substantially better and doesn't promote bacterial evolution (so long as it's not antibacterial soap).

Viruses, not bacteria, cause the vast majority of these ailments.

"Antibacterial soaps would be good if they worked, but they don't seem to do anything," Dr. Gerba reports. Columbia University researchers reported in a study, published in the Annals of Internal Medicine, that families using antibacterial cleaning products experienced about the same number of runny noses, sore throats, and fevers as a control group using ordinary soaps and detergents. Viruses, not bacteria, cause the vast majority of these ailments. However, some suspect that common antibacterial agents used in cleaning products may be nurturing the development of antibiotic-resistant microbes.

Staphyloccus aureus is a common bacteria that can cause many problems from pimples, boils, and cellulitis, a bacterial infection of the skin, to fatal diseases like pneumonia, meningitis, endocarditis, and toxic shock syndrome. In one study, Dr. Gerba tested 25 cell phones and found staph on almost half of them. Cell phones are particularly virulent germ vectors because they are held close to or touching faces and lips, get breathed on at close range, held and operated with hands that may not have been recently washed, and are often stored in warm, dark pockets in ideal conditions for germ incubation.

Keyboards and mice obviously also get touched continuously and frequently become contaminated with germ-generating food residues when users eat at their desks. Microbes get transferred to hands to keyboards and mice to phones and back again as we move from one device to another, building up colonies of potentially disease-causing agents on their vector surfaces. Some disease-causing viruses can survive on hard surfaces for up to 72 hours.

"We don't think twice about eating at our desks, even though the average desk has 100 times more bacteria than a kitchen table and 400 times more bacteria than the average toilet," notes Dr. Gerba.

The key to protecting oneself from microbial infections is to understand vectors - the routes via which disease pathogens enter our bodies - and it so happens that human/machine interfaces of the electronic devices that have become ubiquitous tools of everyday life are also highly efficient disease vectors.

Another expert cited in the AP article, Professor Elizabeth Scott of the Simmons Center for Hygiene and Health in Boston notes that the typical office worker touches hands to face an average of 18 times an hour, essentially transporting the microbial menageries inhabiting keyboards, cellphones, and whatever else we might have touched since the last hand-scrub to the thresholds our respiratory and digestive system every 3-1/2 minutes.

Perhaps even worse, research has shown that while 95% of people say they wash their hands after using a public bathroom, only 67% actually do, just 33% of the hand-washers use soap, and only 16% really wash their hands long enough (long enough being the time it takes to sing a verse of Happy Birthday or Yankee Doodle without hurrying).

Aside from swabbing tactile contact surfaces with disinfectants on a regular and frequent basis, a passive approach is also possible in the form of a growing selection of antimicrobial phones, keyboards and mice. Most of these new gadgets are coated with germ-hostile materials based on silver, which you may see advertised as "nano silver" or "silver ion". Unlike antibiotics, which some believe also weaken your immune system with frequent exposure, silver and hydrogen peroxide (which are even more effective when used in tandem) have not been found to promote the formation of antibiotic-resistant "superbugs". However, antimicrobial coatings on products are not without controversy, about which more in a moment.

A century ago, infectious disease was the number one cause of death. However, Ignaz Semmelweis's discovery in 1847 that washing hands made a (dramatic) difference in surgical outcomes (he was more or less drummed out of the medical profession for his trouble and was eventually committed to a mental institution, where he died just 14 days later, possibly after being severely beaten by guards). This led to Louis Pasteur's and Robert Koch's germ theory of disease, in turn resulting in better hygiene practices (particularly in medical facilities) in the late 19th Century, which was a revolutionary developmental step toward the discovery of antibiotic drugs in the mid-20th Century. By the 1980s, infectious disease had fallen to being the No. 5 killer, but since then it has insidiously crept back up to third place, which makes the sounding of alarm bells about office, cell phone, etc. more than headline-grabbing FUD.

It may or may not be coincidence that the trend reversal happened around the same time that personal computers and cell phones became popular and then near-universal accouterments of contemporary life, but it is certainly an interesting parallel.

In one study, the University of Arizona's Dr. Gerba and his team separated office workers into two groups. One group used disinfecting wipes to clean their desks, phones, and computers once a day while the other did not. Within two days, the wipes users were found to have a 99.9% reduction in bacteria levels. Among people who did not use wipes, bacteria levels increased an average of 19-31% on their telephone, computer mouse, keyboard, and desktop surfaces throughout a typical workday.

My own favorite agents of disinfection are hydrogen peroxide and colloidal silver. While proprietary disinfectants like the Lysol and Clorox products suggested by Apple can certainly do the job, they are problematical for folks like myself and others who are afflicted with multiple chemical sensitivity (MCS). While germs may make me sick, it is 100% certain that exposure to strongly scented cleaning chemicals will make me sick, so the cure may be worse than the original problem. Or not, since non-aromatic alternatives are available.

Both hydrogen peroxide and colloidal silver work as disinfectants, and both are widely (although not unanimously) considered reasonably safe as chemicals go for that sort of use. At standard dilutions, hydrogen peroxide may cause mild skin irritation to extremely sensitive individuals, but that's about the only caveat with respect to topical exposure, while colloidal silver, in my experience, has proved a benign and indeed a wonderful soothing and dealing agent for burns and skin irritation, but that sort of use is not uncontroversial.

According to the British Columbia, Canada, Environmental Protection Department's Water Quality Branch "Silver is a disinfectant for non-spore forming bacteria at concentrations three or four orders of magnitude below the levels at which it is toxic to mammalian life (about 1 gm/day for humans or 500 mg/L in their drinking water)." That's talking about ingestion - not topical skin exposure. There is a condition called Agyria that causes a permanent grayish discoloration of the skin in some individuals who ingest large amounts of silver over extended periods of time.

United States Patent 6027469, a disinfecting system for hemodialysis apparatus issued February 22, 2000, notes: "Hydrogen peroxide is used in hospitals to disinfect surfaces. It is sometimes mixed with colloidal silver. It is often preferred because it causes far fewer allergic reactions than alternative disinfectants."

Hydrogen peroxide also has the advantage of being cheap.

For its part, when colloidal silver comes into contact with a germs like E-coli or staph it essentially smothers the microbe, rendering it unable to breath or reproduce, effectively stopping it in its tracks.

As noted above, another avenue of vector interdiction and prevention has been the use of keyboards, mice, mouse pads, wrist-rests, and even cellphones that have been coated with antimicrobial agents, either organic (i.e., either antibiotics; probably not so good for you) or silver-based.

However, a damper (to say the least) was put on the antimicrobial input device market last March when the EPA fined Aten Technology, Inc., of Irvine, CA, peripherals-maker IOGear's parent company, $208,000 for selling "unregistered pesticides" and making unproven claims about their effectiveness.

"We're seeing far too many unregistered products that assert unsubstantiated antimicrobial properties." Katherine Taylor, associate director of the Communities and Ecosystems Division in EPA's Pacific Southwest region, is quoted commenting, "Whether the claim involves use of an existing material such as silver, or new nano technology, the EPA takes these unverified public health claims very seriously. Consumers should always follow commonsense hygiene practices, like washing hands frequently and thoroughly."

There are also potential environmental issues associated with release of silver nanoparticles into the environment. See Problematic New Findings Regarding Toxicity of Silver Nanoparticles and Groups File Legal Action for EPA to Stop Sale of 200+ Nanosilver Products.

A scientific paper, Are Gold and Silver Nanoparticles Toxic?, by Desma N. Mitchell, Hilary Arnold Godwin, Elizabeth Claudio is available online.

Note also that there is a distinction between colloidal silver and nanoparticle silver, which is explained at nano-silver.com.

Some keyboards and mice (but no cellphones that I've heard of) can also be washed in a dishwasher, which is an effective means of disinfecting them. I haven't been able to find any Mac specific washable keyboards.

Some experts recommend washing contact surfaces frequently with an alcohol-based cleaner, rather than an antibiotic disinfectant, and blowing out detritus that inevitably finds its way to lodge in the under-key world from time to time.

As I said, it's not wise to obsess, but it does make good sense to exercise some cautious prudence in cutting down exposure to disease-causing organisms. Apple's advice is probably worth following, especially if you're involved with computers, telephones, and other tactile-contact devices in a multi-user environment, whether at the office or at home.