Those colorful candles burning brightly atop a birthday cake may look lovely, but apparently blowing them out has some pretty disgusting side effects, researchers say.
A study in the Journal of Food Research determined that blowing out candles over that sweet icing surface resulted in 1,400% more bacteria compared to icing spared the puff.
The study was titled "Bacterial Transfer Associated with Blowing Out Candles on a Birthday Cake," so you don't have to read far to get the idea. But testing involved eating pizza, so the authors aren't total party poopers.
"Preliminary tests of blowing on nutrient agar indicated that bioaerosols in human breath expelled from the mouth may be a source of bacteria transferred to cake surfaces," says the abstract in lingo seldom heard at birthday parties. Nutrient agar, to the uninitiated, is stuff used to cultivate microbes.
To test the bacteria transfer, foil was spread over a Styrofoam™ base, icing spread on the foil and the candles jammed into the entire unappetizing mess. Test subjects ate pizza and then blew out the candles.
Icing samples were "sterilely recovered" and then tested for the level of bacterial contamination and — Voila! — bad stuff was learned.
"Due to the transfer of oral bacteria to icing by blowing out birthday candles, the transfer of bacteria and other microorganisms from the respiratory tract of a person blowing out candles to food consumed by others is likely," the abstract says.
But really, no surprise there. Germaphobes have been making snide comments during the ceremonial and usually awkward lighting of the candles for as long as we've had fire. But Paul Dawson, a food safety professor at Clemson University and co-author of the study, had some news unmentioned in the abstract that can allow you to blow a sigh of relief, although perhaps not on your cake.
“It’s not a big health concern in my perspective,” Dawson told The Atlantic. “In reality if you did this 100,000 times, then the chance of getting sick would probably be very minimal.”