Foil germs that flake: Use bump not shake

Arkansas Democrat-Gazette/CELIA STOREY
Hand in germy glove for ActiveStyle wire filler
Arkansas Democrat-Gazette/CELIA STOREY Hand in germy glove for ActiveStyle wire filler

Since ancient days when warriors shook hands to show they weren't about to pull out their swords, the firm handshake has been a hallmark of polite manners. But research suggests a rowdy high five or a fist bump would be more considerate.

That is, when you're trying to avoid smearing germs on the people you greet. For instance, in a hospital.

A brief report published in the August online issue of The American Journal of Infection Control describes charming experiments conducted by British researchers Sara Mela, a doctoral candidate, and David E. Whitworth, Ph.D., at the Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, a public research university in Wales. (The report is available as a free download from ajicjournal.org.)

They had two people, whose hands were about the same size, don sets of sterile gloves for a series of tests, each repeated five times in random order.

• To see how much skin comes into contact during the three forms of greeting -- the traditional handshake and two so-called "dap" greetings, the high five and fist bump -- they sprayed the "greeting donor" glove with copious amounts of acrylic paint and measured the area of the paint transferred to the "recipient" glove.

They found that the handshake conveyed about twice as much paint as the high five, and the fist bump conveyed about half as much as the high five. So as you might expect, handshaking involves the most physical contact and fist bumping the least.

• For the other tests, the greeting donor dipped a gloved hand into a concentrated culture of bacteria that live in the intestines of warm-blooded animals such as humans, Escherichia coli. (Yes, E. coli; but there are many strains of E. coli, and these harmless bacteria were not one of the sort that causes sometimes fatal gastrointestinal illnesses.)

After each greeting, the recipient would dip his gloved hand into a buffered solution, and then the researchers counted how many bacteria washed into that solution.

The results showed that the handshakes conveyed nearly twice as many bacteria as the high fives; and the fist bump had the lowest transmission of all.

The researchers write, "Because handshakes typically last longer than fist bumps or high fives, bacterial transfer was measured again, with each greeting prolonged for 3 seconds (the duration of the model handshake we employed). Transfer of bacteria did not increase significantly for the prolonged high five ... however, transfer via fist bump was significantly increased by

prolonging for 3 seconds ...."

A three-second fist bump transferred almost as many bacteria as a regular high five.

Also, they wanted to know whether grip strength during a handshake made any difference in how many bacteria moved from the donor to the recipient. Grip strength was tested using a Takei TKK5401 dynamometer.

The result? The greater the gripping pressure, the more bacteria shared. A strong handshake transferred twice as many bacteria as a moderate handshake.

"Outside the laboratory," the authors write, "many other variables will presumably also affect transmission. For instance, the three greetings tested involve contact between different parts of the hand, and it is probable that in everyday life different parts of the hand would have differing amounts of bacteria fauna, which would also depend on the participants' hygiene habits, occupation and location."

And although the research report doesn't address it, there are variations for each form of greeting that could increase bacterial sharing, from the two-handed handshake in which both parties pile up their hands warmly to the multi-angle fist bump where people touch different parts of the fist in a choreographed order.

The researchers write that it is unlikely that a "no-contact greeting could supplant the handshake." But they conclude that "adoption of the fist bump as a greeting could substantially reduce the transmission of infectious disease between individuals."

ActiveStyle on 08/11/2014

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