When was the last time you ate off the ground?

    * Cleaning company buys dropped food study
    * Finds three-second rule applies - sometimes
    * Five out of five mums found guilty

HOW long is too long when it comes to eating off the floor?

According to a study of dropped food - and children's dummies - by Manchester Metropolitan University, it depends on what you're eating.

Within three seconds of hitting the ground, a dummy has already picked up traces of E coli.

"We also discovered Pseudomonas - bacteria which could potentially lead to respiratory, tissue and urinary tract infections, for those whose health is already compromised," MMU Technical officer Kathy Lees told the Daily Mail.

Bad news for parents who've had that "how did that get there" moment when opening their little darling's nappy, but good news for cleaning experts Vileda, who paid for the study.

The team also dropped jam, cooked pasta (thrown spaghetti at a wall, anyone?), ham, biscuits and dried fruit.

The pasta and dried fruit picked bacteria up quickest, but the team said you've got a bit longer with food with a high sugar or salt content.

Dried biscuits and processed food took between five and 10 seconds before bacteria started to form, but were still relatively safe to eat.

Vileda followed the study up with their own research, surveying five mums.

Their alarming findings revealed 100 per cent of mums studied returned dropped dummies to their babies' mouths.

"Our advice is to minimise risk and keep your floor clean by regularly mopping," Vileda, which sells the odd mop or two, said.

"Mop heads need to be replaced every three months."