I don't understand how someone can think this is true. Like, what, you drop your toast with jam on the floor, pick it up in a second, the jam is full of hairs/dust/debris and you figure it's fine?
The thought revolves around dry foods and the (mistaken) impression they're unlikely to accumulate any kind of debris and dust. Peanuts, pretzels, etc.
What's wrong with just explaining that they shouldn't eat stuff from the ground. Period?
Wasting food for no good reason. And making them paranoid about germs.
If they are over that, they're smart enough to understand that they don't eat jelly sandwitch off of the floor, or something they dropped in a public street. But for a casual hard food stuff they dropped on the kitchen floor or living room etc, they can sweep it and eat it -- and get some germ resistance too.
E.g.:
Just as a baby's brain needs stimulation, input, and interaction to develop normally, the young immune system is strengthened by exposure to everyday germs so that it can learn, adapt, and regulate itself, notes Thom McDade, PhD, associate professor and director of the Laboratory for Human Biology Research at Northwestern University.
Exactly which germs seem to do the trick hasn't yet been confirmed. But new research offers clues.
In a recent study, McDade's team found that children who were exposed to more animal feces and had more cases of diarrhea before age 2 had less incidence of inflammation in the body as they grew into adulthood.
Inflammation has been linked to many chronic adulthood illnesses, such as heart disease, diabetes, and Alzheimer's.
"We're moving beyond this idea that the immune system is just involved in allergies, autoimmune diseases, and asthma to think about its role in inflammation and other degenerative diseases," McDade says. "Microbial exposures early in life may be important… to keep inflammation in check in adulthood." (WebMD)
or:
http://news.ubc.ca/2016/08/10/why-your-kids-should-play-in-t...
Are there adults out there who are fussy with their food? In what way?
In other words, if a person saw hairs/dust/debris in their jam that fell on the floor, they wouldn't eat it anyway.
But if something less sticky (and more solid) was dropped, say an apple or a pizza piece that fall on the bread side, they might pick it up, sweep it a little, and eat it.
In fact, 5-second-rule or not, most people will be fine for doing so anyway, as long as they do it on their relatively clean home -- with germs that they are usually in contact anyway.
It might might not be a conscious following of the 5-second-rule, but I'm sure the people in your country would still pick it up fast and not let it collect germs kana eikosalepto before eating it.