Five-second rule is false: scientists

By Nicholas Robinson contact

- Last updated on GMT

'If you drop food on the floor bin it,' says Cutler
'If you drop food on the floor bin it,' says Cutler

Related tags: Bacteria

Scientists have debunked the myth that food dropped on the floor for five-seconds or less is still safe to eat.

While many consumers may be tempted to eat food after dropping it on the floor, it is taboo in pub kitchens.

More than 70% of women and 56% of men surveyed by scientists in 2003 were familiar with the five-second rule and believed that food dropped on the floor within that time wouldn’t be contaminated with high levels of bacteria.

However, Paul Dawson, a professor of food science at Clemson University, claimed the amount of time food was on a surface did not matter. Instead, it was the amount of bacteria on a surface and the type of surface that would affect the overall contamination.

‘Slightly better places to drop food’

Where did the myth come from?

A well-known, but inaccurate, story about Julia Child may have contributed to this food myth. Some viewers of her cooking show The French Chef ​insist they say Child drop lamb (or a chicken or a turkey, depending on the version of the tale) on the floor and pick it up, with the advice that if they were alone in the kitchen, their guests would never know.

  • Source: ​Dr Paul Dawson

“Carpets, for instance, seem to be slightly better places to drop your food than wood or tile,” Dawson said in the online journal Quartz.

“When carpet was inoculated with Salmonella​, less than 1% of the bacteria were transferred. But when the food was in contact with tile or wood, 48–70% of bacteria transferred.”

If there were millions of cells on an area where food was dropped it could take as little as 0.1% of those to contaminate the product and make someone ill, he added.

“In the rare circumstance that there is a microorganism that can make you sick on the exact spot where the food was dropped, you can be fairly sure the bug is on the food you are about to put in your mouth,” Dawson said.

For example, 10 sells or fewer of a virulent strain of E. coli ​could cause severe illness or death in people with a compromised immune system, Dawson warned. However, the chance of such a strain being on most surfaces was very low, he admitted.

Most-likely to cause contamination

It wasn’t just dropping food on the floor that could cause bacterial contamination. Raw food, moist surfaces, hands, skin, coughing and sneezing are among some of the media most-likely to cause contamination, Dawson explained.

“Hands, foods and utensils can carry individual bacterial cells, colonies of cells or cells living in communities contained within a film that provide protection,” he added.

“These microscopic layers of deposits containing bacteria are known as biofilms and they are found on most surfaces and objects.”

The advice from National Health Service scientist and Queen Mary University of London microbiologist Dr Ronal Cutler is simple: “If you drop food on a floor, it’s better to put it in the bin rather than in your mouth.

“No matter if it’s at home on the carpet, the kitchen floor or in the street, my advice is if you drop it, chuck it.”

Related topics: News, Health & safety, Food, Legal

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