Please rub your hands

by Margo White / 30 December, 2011
Thought the best way to wash your hands involved soap? Actually a Hail Mary and plenty of friction does the trick.

Chances are if you visit a public rest room over the summer, there’ll be no soap left in the soap dispenser. Never mind – latest news from the world of hand hygiene research reveals you don’t need soap to eradicate the invisible bacteria lurking in the palms of your hands. Rather, the crucial variable in a good hand wash is the friction generated by rubbing your hands together.

This is according to Dr Tom Miller and colleagues at the University of Auckland. Millar has become one of New Zealand’s leading luminaries on hand hygiene, at least since 1997, when he published a study that showed washing one’s hands was a redundant exercise if it wasn’t followed by thorough drying. Moisture, he pointed out, is a “microbial mobiliser”, and a damp hand provides an ideal environment in which bacteria can be passed on and picked up.

He followed that up with studies in which he compared the hand-drying resources available in the typical public toilet – paper towels, cloth towels and air dryers – to see which worked best. (The short answer: towels followed by 10 seconds under an air dryer.)

Having researched the complexities of hand drying, and influenced public health campaigns all over the world, and perhaps even the facilities provided in a few public rest rooms, Miller recently turned his attention to hand-washing. The area was ripe for investigation, he says. “You might think that would have been worked over, but when we went to look at the literature, just about all the instructions were based on intuition, on what seems about right, rather than any facts.”

And so Miller and his team drew on the volunteer services of colleagues who were willing to be contaminated with a sample of their own E coli – unsurprisingly, people have less objection to being contaminated with their own bugs than somebody else’s. He then got them to enact three possible scenarios: holding their hands under the tap for a period of time; rubbing their hands “purposefully” under a tap without soap; washing their hands as they normally would with soap and water.

“After two years of jolly hard work” they found that holding one’s hands under running water is a waste of time, but rubbing hands together “purposefully” under a running tap is extremely effective. After 10 seconds of rubbing, 95% of the microbes had been removed. After 20 seconds, 99% had gone. Interestingly, soap slowed down the rate of decontamination, at least initially, as soap decreases the friction. “But after about 20 seconds you ended up at the same point because you had got rid of the soap and the friction value was restored.”

Miller is reluctant to suggest that we abandon soap altogether. It’s useful when we have visible muck on our hands, as it gets rid of grease and dirt in a way that water doesn’t. But most of the time we wash our hands to get rid of that which we can’t see, in which case soap may not be imperative. “I think the value of using soap is that you tend to keep hands under the tap for longer, so we wouldn’t discourage using it. But the message is that you don’t need soap to decontaminate.”

This conflicts with the message most of us grew up with, as well as with what is promoted by soap manufacturers and marketers who have seized upon the profile hand hygiene has received in recent years (bolstered by the odd flu pandemic) and have developed all sorts of products as a result. Such as all those fashionable anti-bacterial soaps. “They have very little to offer above a normal soap,” says Millar, going on to point out that disinfection takes time. “The average hand wash is 20 seconds. There’s no way an antibacterial can act in that time.”

Alcohol-based gels and wipes have their merits, when there isn’t any alternative, but he also points out they need to kill the micro-organisms to be effective, so it’s generally more efficient to wash them away. “I think their principal advantage is they do dry the hands out, so you’re not going to be transferring and picking up microbial contaminants.”

In other words, it’s time to revise our understanding of what makes a good hand wash; use soap if you want, but focus on the friction. Miller recommends rubbing hands and fingers together under running water for 20 seconds. Asked whether anyone is really likely to count to 20 while rubbing their hands together, he suggests a Catholic approach. “Just say a Hail Mary. Slowly.”


A study published in the British Medical Journal has supported the argument that breast screening in the UK causes more harm than good; harms include false positives, such as abnormal results that turn out to be normal, and treating patients for harmless cancers that, if left untreated, would not have caused any symptoms. Breast screening was initiated in the UK after the 1986 Forrest Report, which the authors of the BMJ study say overestimated the benefits of screening and didn't consider the risks.


There's little evidence that supplementing the diet with individual vitamins and nutrients will protect against stroke, but a healthy prudent diet might. A study published in the Lancet that reviewed the literature on various individual vitamins, nutrients, foods and diets and their effects on stroke risk concluded that neither antioxidant vitamins nor B vitamins appeared to protect against stroke, but a prudent low-fat, high-potassium diet, such as the Mediterranean diet, might. In other words, eat well and not too much.


Researchers at Vanderbilt University have produced more evidence that the recreational use of Ecstasy, the party drug that produces feelings of euphoria, also leads to a chronic loss of serotonin. Serotonin is involved in regulating mood, appetite, sleep, learning and memory. It is also increasingly being investigated for its therapeutic value in, for example, post-traumatic stress disorder and anxiety, so researchers say It's crucial they better understand at what point the drug becomes toxic.


Fine lines: New Anzac books and graphic novels for kids
105028 2019-04-25 00:00:00Z Books

Fine lines: New Anzac books and graphic novels for…

by Ann Packer

A telegraph “boy”, heroic animals and even shell-shock make for engaging reads for children.

Read more
Keeping up appearances: The challenging job of restoring NZ's lighthouses
104978 2019-04-25 00:00:00Z Life in NZ

Keeping up appearances: The challenging job of res…

by Fiona Terry

Ensuring lighthouses stay “shipshape” isn’t a job for the faint-hearted.

Read more
The former major reuniting service medals with their rightful owners
105015 2019-04-25 00:00:00Z Life in NZ

The former major reuniting service medals with the…

by Fiona Terry

Service medals are being reunited with their rightful owners thanks to former major Ian Martyn and his determined research.

Read more
PM announces 'Christchurch Call' to end use of social media for terrorism
104952 2019-04-24 00:00:00Z Politics

PM announces 'Christchurch Call' to end use of soc…

by Noted

A meeting aims to see world leaders and CEOs of tech companies agree to a pledge called the ‘Christchurch Call’.

Read more
Red Joan: Judi Dench almost saves Soviet spy story from tedium
104942 2019-04-24 00:00:00Z Movies

Red Joan: Judi Dench almost saves Soviet spy story…

by James Robins

The fictionalised account of a British woman who spied for the Soviet Union is stiflingly quaint.

Read more
What to watch on TV this Anzac Day
104749 2019-04-24 00:00:00Z Television

What to watch on TV this Anzac Day

by Fiona Rae

Māori TV once again devotes the day to Anzac programming, including a live broadcast from Gallipoli.

Read more
Twist in the tale: Why Margaret Mahy changed the end of her classic debut
104490 2019-04-24 00:00:00Z Books

Twist in the tale: Why Margaret Mahy changed the e…

by Sally Blundell

The two different endings of the beloved A Lion in the Meadow still provoke debate. So which is better, the 1969 original or the later, kinder one?

Read more
Mapping the second brain: The latest science on the effect of your gut bacteria
104884 2019-04-24 00:00:00Z Health

Mapping the second brain: The latest science on th…

by Donna Chisholm

Most of us have heard the five-plus-a-day message for fruit and vegetables. But new research into gut health suggests that advice may need tweaking.

Read more