It’s official.  The “three second rule” will not kill your child.

If you drop a dummy or a piece of food on the floor or ground, picking it up immediately, wiping it off, and giving it to your child may not be the worst kind of germs. Of course, this is within reason and good judgement that said floor or ground is not covered in cow pizzas (aka dung) or puppy pee.

The clever scientists at the John Hopkins Children’s Centre in the US found that babies with early exposure to bacteria and certain allergens may have a protective effect by shaping their immune responses – helping to inform preventive strategies for allergies and wheezing, both precursors to asthma.

"Our study shows that the timing of initial exposure may be critical," says study author Robert Wood, M.D., chief of the Division of Allergy and Immunology. "What this tells us is that not only are many of our immune responses shaped in the first year of life, but also that certain bacteria and allergens play an important role in stimulating and training the immune system to behave a certain way."

And it’s not just a little dust mixed with trodden crumbs he refers to. The three culprits tested were cockroach droppings and mouse and cat dander (this is what animals shed from their skin and fur). Infants who grew up exposed to these within the first 12 months of life had lower rates of wheezing at age 3, compared with children not exposed to these allergens soon after birth.

And even more astounding to a clean freak like me, the protective effect was additive. Apparently, infants exposed to all three allergens had a lower risk than those exposed to one, two or none of the allergens.

Now I don’t in any way propose feeding your precious mini-me lunch coated in floor “flour” or ground “grime”, but there’s no need to obsessively douse them with detergents ten times a day. And if you are a cat lover, it seems to be okay for Kitty to roam free to keep the house, mouse free…though it seems the little critters are not a health hazard either.

But no matter what the experts say, and call me old-fashioned, because I still believe in washing hands before eating is a good habit.