It's the basic nature of young children to touch the very things in their environment that their parents find most disgusting. Just try to keep your 1-year old from sticking the dog's bone in her mouth!
After a year of swine flu scares, health authorities imploring regular hand washing, and talk of sanitizer gel like it was liquid gold, it's tough not to worry about what your children are getting into and the ultimate impact it will have on their health.
Infectious diseases are a legitimate cause for concern, but some would argue that our society has gone overboard when it comes to protecting our kids from germs.
How clean an environment do our kids really need for good health? Here's what experts told WebMD.
A mounting body of research suggests that exposing infants to germs may offer them greater protection from illnesses such as allergies and asthma later on in life.
This line of thinking, called the "hygiene hypothesis," holds that when exposure to parasites, bacteria, and viruses is limited early in life, children face a greater chance of having allergies, asthma, and other autoimmune diseases during adulthood.
In fact, kids with older siblings, who grew up on a farm, or who attended day care early in life seem to show lower rates of allergies.
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."
Purging Germs: Health booster or bad idea?
Most of the germs lurking about our environment and that live on our bodies are not only harmless; they've been with us for millennia, says Martin Blaser, MD, professor of internal medicine at New York University.
As human behavior has changed over the past half century, many microbes, such as some that live in the gut, are disappearing.
"These perform important physiological functions but because of modern life they are changing and some are disappearing," Blaser says. "Those disappearances have consequences -- some good, some bad."
When we overly sanitize infants' environments to protect them from illness, we may instead be depriving them the opportunity to build a strong immune system.
In addition to overzealous hygiene campaigns that may prevent kids from exposure to natural microorganisms that are good for them, there are other practices -- like the overuse of antibiotics -- that threaten to make us less healthy, not more.
Still, there is the possibility of going too far in the other direction. Many proponents of the hygiene hypothesis say that the germs in the dirt are good for you.
"It's an interesting idea," Blaser says, "but my view is those germs are irrelevant to us. Those microbes in dirt are adapted to dirt; they are not adapted to the human body."
So What's a Parent to Do?
As with most things in life, keeping your kids healthy is a matter of finding balance.
Blaser highly recommends that parents and physicians carefully consider whether antibiotics should be used for all episodes of fever. Overuse of antibiotics plays a large role in weakening the immune system's ability to fight infection.
And when it comes to keeping your kids' environment germ free, McDade says, "I'd like to see a recalibration toward common sense. You don't have to wash or sanitize everything."
Keep things around the house clean, he says, but remember that using harsh chemicals to sanitize, such as bleach, might be more harmful to your children than any lingering germs. And the next time your toddler picks up and eats food he just dropped on the floor, take a deep breath and just walk away.