For those who will jump for a slice of birthday cake, you might want to think twice. You may want to rethink accepting a slice of cake after the birthday boy or girl blows out the candles. Next time you blow out the birthday candles, make a wish that you don’t catch anything.
A recent study, “Bacterial Transfer Associated with Blowing Out Candles on a Birthday Cake,” has found that blowing out birthday candles spreads tiny drops of saliva and tons of bacteria onto the cake. All that huffing and puffing increases the amount of bacteria on a cake by 1,400 percent, the study reveals.
The researchers at Clemson University said in their paper they hoped the results “may help raise awareness of possible health risks associated with birthday celebrations and encourage others to take steps toward preventing the spread of bacteria.”
Dr. Paul Dawson, a professor at the university, conducted the study with a group of his undergraduate students to get them thinking about food safety. He normally looks into things like the five-second rule or the risk of sharing food but said he got the idea for this study from his own experience as a father.
Dawson said the idea for the study came from his teenage daughter. But he’s also conducted a whole set of studies around common questions in food safety with his undergraduate students, as a way of engaging them in original scientific research.
According to the study, the researchers made the gross discovery by scarfing down pizza for authenticity blowing out candles on an iced hunk of Styrofoam and then measuring bacterial contamination. The amount varied a lot depending on who did the blowing, they found. “Some people blow on the cake and they don’t transfer any bacteria. Whereas you have one or two people who really for whatever reason, transfer a lot of bacteria,” Professor Paul Dawson told.
The research team put frosting on a piece of foil atop a cake-shaped Styrofoam wheel, which they stuck candles in. Before blowing out the candles, they all ate pizza, to ‘simulate a birthday party,’ and ‘help the salivary glands get going.’ They then lit the candles and blew them out. To count bacteria, the team diluted the frosting with sterilized water and then spread it out on agar plates for the bacteria to grow.
Dr. Dawson noted that this isn’t the most precise way to count bacteria, because not each one will grow on an agar plate. There are now more expensive and precise ways to count bacteria cells, but this is a classic baseline method. The team of researchers found that there was a lot of bacteria, but more surprisingly, that each blow resulted in different types of bacteria.
The blowing increased a number of bacteria on the frosting by an average of 15 times although one person’s saliva increased the infestation by 120 times, he said. But Dawson doesn’t think most birthday revelers are likely to get sick from the ceremonial tradition if we did, it probably wouldn’t be such a popular pastime.
“It’s not a big health concern in my perspective. In reality, if you did this 100,000 times, then the chance of getting sick would probably be very minimal,” he told. Our mouths are teeming with bacteria, most of them not harmful. If birthday cakes significantly contributed to the spread of deadly diseases, it’d be obvious by now given the ubiquity of the practice.
Human mouths are full of bacteria, and most of them are not harmful. Additionally, if blowing out candles on a birthday cake actually caused the spread of deadly diseases it would be obvious because of how common the practice is, especially in children. Dr. Dawson said he might avoid the cake if he thought the candle-blower looked sick, but otherwise thought it was probably fine.
This is not the first time he’s done studies like this. In 2015, he shared a controversial article for anyone who likes to double dip their chips, saying that doing it is not only socially unacceptable but could risk the spread of infectious diseases.
So, guys, be careful while blowing out birthday candles or avoid blowing candles.
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