"Antibacterial handwash is NO better than soap – and cold water kills as many germs as hot, experts claim," The Sun reports.
These were the main findings of a study looking at various methods of handwashing.
The study found using colder water (15C) was just as effective at getting rid of bacteria as using hot water (38C), and antibacterial soap was not significantly more effective at removing bacteria than plain soap.
It also found washing your hands for slightly longer – 30 seconds as opposed to 15 seconds – is more effective at getting rid of the bacteria.
The researchers hope their study could be used by policymakers to inform handwashing guidelines.
But the study only compared two products, and also only looked at one organism, which doesn't cause infection in humans.
Examining the effectiveness of a wider range of products against other types of infectious organisms, such as viruses and fungi, as well as other strains of bacteria, would be required before we can safely say whether cold water is just as effective as hot.
Perhaps the most useful piece of advice to come from the study is to wash your hands for 30 seconds if you want to protect yourself against food poisoning or infections like the flu.
The study was carried out by researchers from Rutgers University and GOJO Industries, both in the US.
No external sources of funding were reported, though it should be noted that GOJO Industries produce hand soaps and sanitiser products.
The study was published in the peer-reviewed Journal of Food Protection.
The Sun, the Daily Mail and BBC News all covered the study. Their reporting was accurate.
This experimental study aimed to assess handwashing techniques by testing the most effective soap volume, water temperature, and lather time for getting rid of harmful bacteria.
Handwashing techniques have generated interest and been a topic of debate for a long time, with particular reference to frequency, duration, and technique.
But handwashing recommendations aren't always backed by evidence. The researchers wanted to address this gap in the data.
Researchers recruited 20 volunteers from Rutgers University to take part in this study – 10 men and 10 women with an average age of 25.
Volunteers were asked not to use any type of antimicrobial soap or hand sanitisers for the full duration of the study.
Before beginning the experiment, 1ml of a strain of E.coli that doesn't cause infection in humans was added to each volunteer's hands.
The experiment evaluated four variables as part of handwashing technique:
One variable would be changed while the other variables remained constant to study the effect of each one. Each experiment was replicated 20 times.
Volunteers were given instructions on how much soap to use (number of pumps), when to wet their hands, when to stop lathering, and when to stop rinsing.
They were asked not to dry their hands at the end of the experiment so any remaining bacteria weren't removed.
Samples were collected from the volunteers' hands immediately after they were washed.
Comparisons were then made between each handwashing technique and the number of bacteria left on the volunteers' hands after each experiment.
Overall, there were some interesting findings:
The researchers concluded that, "The results of this study indicate that water temperature is not a critical factor for the removal of transient micro-organisms from hands.
"Overall, the length of lather time and volume of soap used did not make a large difference, but a minimum of 0.5ml of soap and 10s of lather time is recommended based on our findings.
"Understanding which behaviours, human factors, and physiological differences influence handwashing the most may allow future studies to focus on which techniques can optimise the effectiveness of handwashing and thereby reduce infection transmission risk and improve food safety."
This experimental study aimed to assess handwashing techniques by testing the most effective soap volume, water temperature, and lather time for getting rid of bacteria.
Contrary to current guidelines, which recommend using hot water when we wash our hands, this study found using colder water (15C) was just as effective at getting rid of bacteria.
It also found washing your hands for longer – 30 seconds – was found to be more effective than washing for 15 seconds.
The researchers hope their study will help policymakers such as the US Food and Drug Administration (FDA) to make evidence-based recommendations around handwashing techniques.
But this was a very small study with a sample size of just 20 participants. It only compared two products: a plain soap with no specific antimicrobial ingredients and an antimicrobial soap that included 1% chloroxylenol.
A more comprehensive assessment is needed, studying many more products and organisms, before we can consider changing handwashing recommendations.
Current guidelines recommend that we wash our hands with water and soap for at least 20 seconds:
Read more advice about handwashing.