WE’RE ALL FAMILIAR with the ancient institution that is the five-second rule.

It states that a piece of food may be eaten when it falls, on the condition that it is retrieved and eaten within five seconds. Anything more, and you’re looking at a world of bacteria. But, like all highly-scientific facts, this one has been taken into question m ore than once.

A 2007 study found that it didn’t matter if food was place on a surface for five or 60 seconds the bacteria on the surface mattered more than the time the food remained there.

It looks like what’s at issue is less how long your food languishes on the floor and much more how infested with bacteria that patch of floor happens to be.

The type of surface you drop the food on should also be taken into consideration.

Dr Paul Dawson of Clemson University wrote a blog for The New Republic, which confirmed that

Carpets, for instance, seem to be slightly better places to drop your food than wood or tile. When carpet was inoculated with Salmonella, less than 1 per cent of the bacteria were transferred. But when the food was in contact with tile or wood, 48-70 per cent of bacteria transferred.

In terms of how the bacteria can effect you, it all depends on how many cells are on the surface and the type of bacteria it is. Particular types of bacteria would only take a small amount to make you sick, but the chances you’ll drop food on them can be quite slim.

In the rare chance that there is a microorganism that can make you sick on the exact spot where the food dropped, you can be fairly sure the bug is on the food you are about to put in your mouth.

SO NOW. Drop in on the street, probably leave it. Drop it on your cleaned sitting room carpet? Should be grand.

This might be the most grim ham and cheese sandwich ever spotted in Ireland >

Tesco just confirmed that it’s putting more of those killerchilli peppers on sale >