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Many of us are guilty of eating food off the floor because of the so-called ‘five-second rule’ – but a doctor has spilled the dirty truth behind the age-old myth.
Dr Karl Kruszelnicki has debunked the misconception, explaining that food dropped on the ground or table is not always safe to eat as it can become contaminated with germs instantly – not just after five seconds.
‘Are you seriously asking me to believe that all those bacteria on the table have little stopwatches and they’re just waiting?’ the Aussie scientist said in an amusing video.
‘And after this foodie goodness has descended from heaven, the bacteria start their stopwatches and go, ‘Hang on, guys… three, four…’ and then they jump on the count of five?
‘No, that’s ridiculous.’
Dr Karl explained that the five-second rule does not apply when considered from a scientific perspective on bacteria and infectious diseases.
‘Here’s what the science tells us. First, the majority of the bacteria are transferred across on impact and then it just slowly increases,’ he said.
Secondly, he said the amount of bacteria that transfers depends on the ‘intimacy of contact’.
Many of us are guilty of eating food off the floor because of the so-called ‘five-second rule’ – but Dr Karl Kruszelnicki has spilled the dirty truth behind the age-old myth
‘So, how much surface area of the food is kissing the surface area of the table or the floor?’ Dr Karl explained.
‘On one extreme you’ve got wet, squishy watermelon on a hard tile surface, making for really good contact.
‘On the other end, you have something like an apple with skin landing on a prickly carpet where there’s less surface area and fewer bacteria coming across.’
However, Dr Karl pointed out a third issue: the bacteria.
‘Most of the bacteria are not bad guys… they just hang around doing their own things, they’re not out to get us,’ he said.
Despite reassuring Aussies that most bacteria are harmless, he warned of the potential risks of food poisoning.
‘Food poisoning is a real danger,’ he said.
‘The risk is relatively small in terms of numbers – but it is a bit of a risk.’
Dr Karl explained that the five-second rule does not apply when considered from a scientific perspective on bacteria and infectious diseases
Salmonella can live on surfaces for up to 32 hours, with some research finding that the bacteria can survive for even longer periods, depending on the conditions.
During a 2006 US study, a group of scientists applied a harmful bacterium called salmonella typhimurium to a tile.
The researchers then used bologna sausage as the food to catch the salmonella. Shockingly, over 99 per cent of the bacteria had transferred in less than five seconds.
Dr Karl’s video sparked a discussion, with one joking: ‘Way to ruin the five-second rule’, to which he replied: ‘It is what it is.’
‘An easy way to disbelieve the five-second rule is to picture the same food being dropped on a fresh dog poo,’ another shared, to which Dr Karl agreed.
‘I have lived to over 50 years old with the five-second rule (sometimes counting slowly) and drinking hose water… that’s my science,’ one revealed, laughing.
‘I’m pretty sure the five-second rule is used as a joke, we know it’s gross, we just feel like eating our cookie,’ another added.
