A study has suggested that blowing birthday candles could be a health hazard as it facilitates bacteria transfer. The action would leave the cake's icing riddled with bacteria up to a thousand times.

The research was conducted by a team from the Clemson University, which gathered new data on bacterial transfer through the cake icing and small birthday candles.

More specifically, the study was to look into the transfer of respiratory microorganism from one person to another through blowing birthday candles on cakes, by evaluating the level of microorganisms present.

Dr Paul Dawson, lead researcher and a professor at the university, noted that the practice of blowing candles is commonplace, making the threat of “passing bacteria” common.


“I got the idea actually from my daughter in a casual dinner conversation when I was explaining the project to her,” according to Dr Dawson, as quoted from the Daily Mail.


For the study, the team simulated a birthday cake blowing by putting foil on a styrofoam, layering the frosting and putting candles on top.


The study had 11 test subjects, and the test was replicated three times, for a total of 33 observations.


Before blowing the candles, the test subjects ate pizza “to simulate a birthday” scene, according to the researchers. There were the “blow” group and the “no-blow” group.


After which, the researchers took the samples and added sterilized water and put on agar plates for the bacteria to grow colonies. Each colony represented one bacteria cell.


“Blowing out candles over icing resulted in 15 times more and statistically a higher number of bacteria recovered from icing compared to icing that did not have candles blown out,” the researchers wrote.

Furthermore, some people may transfer more bacteria compared to others, and that each exhalation resulted in different types of bacteria. The study was published in the Journal of Food Research.

However, even after the findings, Dr Dawson remarked that it should not worry birthday party goers.

If the practice of cake candle blowing actually caused the spread of serious diseases, it would have been widely-known. MIMS

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