There’s nothing unusual about kids who have grimy hands, crawl around on a not-so-clean floor, pick up yucky stuff of the street, and who put everything they find – no matter where it comes from- in their mouths. It’s the way a child explores the world around them. Parents on the other hand, spend a good deal of time trying to keep their kids clean and worrying about germs. It’s tiring, and apparently not very productive.

A new study suggests that a limited amount of germ exposure is a good thing and parents should put down the washcloth and back away.

Actually, several studies have suggested that too much cleanliness isn’t healthy. Kids who grow up on farms, where they are exposed to more outdoor activity and germs, are less likely to get sick from immune system disorders like asthma, allergies, inflammatory bowel disease and multiple sclerosis.

This latest study looks at the “ hygiene hypothesis.” The hypothesis is that we are not stimulating a portion of our immune system with bacteria and viral infections the way we used to. Hence we are not building a strong immune system that can help fight off certain diseases.

Scientists at the Brigham and Women's Hospital in Boston, US, led the study that was published in the online issue of Science.

The researchers used mice and divided them into two separate groups. One group was kept germ-free, and the other group was allowed to live in a normal captive environment.

They bred both mice to develop forms of asthma and inflammatory bowel disease (IBD) and compared their immune systems.

Researchers discovered that there was a significant incidence of inflammation of the colon and lungs in the germ-free group when they were eventually exposed to microbes. The symptoms were characteristic of asthma and colitis.

These symptoms have been linked to an overactive immune response, something both humans and mice share. When exposed early in life, the germ-free mice eventually developed a normal adult immune system and immune response. Those exposed later in life did not have as long lasting effects, and the adults that were exposed had a lower resistance to disease than did the exposed adolescent mice.

Many scientists already lean towards the idea that our rapid rise in food allergies, asthma and other immunological diseases are due in part to our obsession with cleanliness, anti-bacterial cleansers and antibiotics.  We don’t like to take a chance on germs causing any kind of illness, and some parents have bought into the idea that “you just simply can’t be too clean.”

But, as science has shown and generations of dirty kids have proven, a little dirt can be a good thing, especially when your child is young and his or her immune system is beginning to flex its muscle. So maybe it’s a good idea to put down the anti-bacterial soap, take a deep breath and let a little dirt do its thing.