Washing hands in cold water as good as hot: Study

Washington: Washing your hands in hot water may be pointless as scientists have found that cold water is equally effective at killing germs.

Researchers also found that washing even for 10 seconds significantly removed bacteria from the hands.

"People need to feel comfortable when they are washing their hands but as far as effectiveness, this study shows us that the temperature of the water used did not matter," said Donald Schaffner, professor at Rutgers University in the US.

In the study, high levels of a harmless bacteria were put on the hands of 21 participants multiple times over a six- month period before they were asked to wash their hands in 60 -degree, 79-degree or 100-degree water temperatures using 0.5 millilitre (ml), 1 ml or 2 ml volumes of soap.

"This study may have significant implications towards water energy, since using cold water saves more energy than warm or hot water," said Schaffner.

While the study indicates that there is no difference between the amount of soap used, more work needs to be done to understand exactly how much and what type of soap is needed to remove harmful microbes from hands, researchers said.

"This is important because the biggest public health need is to increase hand-washing or hand sanitising by food-service workers and the public before eating, preparing food and after using the restroom," said Jim Arbogast, co-author of the study published in the Journal of Food Protection.

These findings are significant, particularly to the restaurant and food industry, because the US Food and Drug Administration issues guidelines every four years, researchers said.

Those guidelines currently recommend that plumbing systems at food establishments and restaurants deliver water at over 37 degrees Celsius for hand-washing, they said.

Schaffner said the issue of water temperature has been debated for a number of years without enough science to back- up any recommendation to change the policy guidelines or provide proof that water temperature makes a difference in hand hygiene.