Feature

True or false: myths debunked

Lester Kok gets NTU experts to bust a few health and safety myths

“Food dropped on the floor for three seconds or less is safe to eat.”
We’ve all heard of the three-second rule – as long as you pick up that cookie that fell to the floor within three seconds, you can eat it without worries.

Research, however, shows that most surfaces like table tops and floor tiles contain millions of bacteria, some of which are quite nasty and can cause food poisoning.

Prof Staffan Kjelleberg, Director of the Singapore Centre on Environmental Life Sciences Engineering at NTU and a renowned expert on microbes, suggests observing the “zero-second rule” instead.

"Research found that pasta that fell on a tile attracted most of the bacteria from the tile in seconds. I wouldn't recommend eating food that has fallen off your plate, as you risk ingesting millions of microorganisms that could harm you.”

Myth busted – so don’t pick up food that lands at your feet or on the food court tray.

“The amount of fat cells in your body is determined before the age of 12. So if you eat a lot of junk food as a kid, you’ll become a fat adult.”
Plump kids become rotund adults, right?

Recent reports have also blamed sugar and a diet high in junk food for causing obesity in kids and subsequently in their adult lives.

How large we become depends more on our lifestyle than our level of fatness at puberty, says Assoc Prof Fabian Lim from NTU’s Lee Kong Chian School of Medicine.

The number of fat cells in our body actually remains relatively stable throughout our lives, meaning that any increase in girth results from fat cells enlarging as more fat is stored.

“While genes do set the ‘baseline’ of fatness in each individual, our lifestyle actually determines whether we stay close to our baseline or store more fat,” says the expert in exercise physiology and metabolic diseases.

“If you don’t want to be chubby as an adult, develop good dietary habits from a young age and include sports and exercise in your weekly routine.”

“There’s nothing germier than public toilets.”
Public toilets are often seen as one of the filthiest places. While it’s true that the washroom does harbour some nasty bacteria, such as around the toilet bowl, the taps and even the door handles, the real danger is much closer than we think.

Research has found that computer keyboards and the touchscreens of smartphones and tablets actually harbour a lot more bacteria than toilet seats.

Enterobacteria, which include strains of E. coli and salmonella, have been found on such devices, with the dirtiest tablets having 15,000 units of bacteria per swab. Toilet seats, in contrast, had less than 10 units of bacteria per swab.

This means it makes more sense to wash your hands after using your mobile devices instead.

Senior Research Fellow Chong Tzyy Haur from the Nanyang Environment & Water Research Institute says we should cut down on bad habits, like snacking or eating while typing and using our mobile devices while on the throne.

It’s also possible that the bacteria from everyday surfaces like door knobs and taps get transferred onto our gadgets.

“What we should all probably do is clean our smartphones from time to time with a damp cloth, and wash our hands after using the toilet and also before every meal, just like what we’ve always been reminded to do,” says the NTU scientist.

“Having my smartphone or tablet turned on during a flight will affect the plane’s navigation systems.”
The flight attendant announces on board that all mobile phones and electronic devices must be switched off before takeoff and during landing. This is because the electromagnetic signals generated could interfere with the plane’s navigation system.

But plane passengers on some flights are now told it’s all right to leave their mobile device on, as long as it is in flight-safe mode – meaning the phone’s antenna is turned off.

Do smartphones really have an effect on a plane’s navigation system?

Assoc Prof Randy Chue from NTU’s School of Mechanical & Aerospace Engineering says aircraft makers like Boeing have found during tests that a small number of mobile devices can cause interference to navigational equipment.

“However, navigational equipment is very hardy and it has been shown to withstand interference from mobile devices,” says the aerospace engineer.

“But while no air crashes have been attributed to mobile phone interference, it's best to follow the instructions given by the airlines regarding what to do with your phones and tablets.”

“When a mobile phone or communication device is switched on in an airplane, it attempts to connect to the cell towers that the plane is currently flying over. Because the plane is high above the ground and flying above several cell towers at the same time, all of these towers will simultaneously attempt to connect to the phone,” Assoc Prof Chue explains. “This overloads the mobile phone network and is the real reason why you aren’t allowed to use your mobile devices during flights.”

If you’re wondering why some flights now allow mobile phone use, that’s because the new generation of aircraft can shield transmission signals, preventing them from leaving the airplane.

However, since laws governing mobile phone use on planes differ across countries, you should listen to the instructions given on board.