Dirt Is Good for Children
Old folklore wisdom stated that “A little dirt never hurt anyone,” or “Everyone must eat a pound of dirt before they die.” As so often proves the case, the knowledge of the pre-scientific world was based on common sense and observation.
Babies seem to know instinctively that dirt is good for them; when they find something of interest on the ground it usually goes straight in their mouths. As Jane E. Brody writes in The New York Times, “Since all instinctive behaviours have an evolutionary advantage or they would not have been retained for millions of years, chances are that this one too has helped us survive as a species. And, indeed, accumulating evidence strongly suggests that eating dirt is good for you.”
Few parents today tell children to “Play outside and get dirty.”
Moms and dads have been guilted by advertising into raising their little treasures in an antiseptic, germ-free environment. Kids mustn’t be allowed to touch anything that hasn’t been wiped clean, disinfected, and sterilized. We are advised to:
- dose the little ones up with an oral antiseptic;
- bathe them daily in an anti-bacterial cleanser; and,
- slap on a coating of germ-killing cream.
The British lobby group parentsoutloud.com says that an overabundance of government health and safety regulations has created an artificially cleansed environment around children.
The guiding force of parentsoutloud is Margaret Morrissey, and she is quoted by The Telegraph as saying: “Parents have become so paranoid about their children playing outside and getting dirty that today’s youngsters are not enjoying a proper childhood.”
Morrissey blames living in an antiseptic bubble for tripling of the number of children developing food allergies.
Tom Brady of The New York Times writes that the incidence of peanut allergies “tripled from 1997 to 2007, an epidemic for which there is no clear explanation.”
The Hygiene Hypothesis
Nobody disputes that good hygiene reduces infections, but research suggests we shouldn’t be obsessive about it.
In November 1989, David Strachan, an epidemiologist, wrote an article in The British Medical Journal in which he proposed the existence of what came to be known as “The Hygiene Hypothesis.”
Dr. Strachan was studying the incidence of hay fever and eczema when he noticed that these allergy-based problems cropped up less frequently in children who came from large families when compared with kids from single-child families.
He speculated that exposure to germs during early childhood gives the human body better protection against allergies.
Mark Holbreich has studied the incidence of allergies among the Amish in Indiana. According to The New York Times he “discovered that just 7.2 percent of the 138 Amish children he tested were sensitized to tree pollens and other allergens, as opposed to about half of all American children.”
Why the difference? It’s the barn or, as European scientists call it, the “farm effect.” Almost all Amish children grow up on farms, and, says The Times “The theory is that microbes from the cowshed, plant material, and raw milk stimulate the immune systems of children and protect them from allergies.”
Dirt Helps Skin Heal
Writing in The Telegraph, Murray Wardrop reports that researchers in the United States have found a scientific explanation for the hygiene hypothesis. “Scientists have discovered that bacteria on the surface of the skin play an important role in combating inflammation when we get hurt. The bugs dampen down overactive immune responses, which can lead to rashes or cause cuts and bruises to become swollen and painful.”
By over-sanitizing their children’s environment, parents may be impairing the ability of the harmless bacteria to aid the healing process.
Dermatologist Professor Richard Gallo of the School of Medicine at University of California, San Diego led the research team that made the discovery. The results have been published in the scientific journal Nature Medicine and reported by BBC News as showing that “a common bacterial species, known as Staphylococci, blocked a vital step in a cascade of events that led to inflammation.”
The bacteria “did this by making a molecule called lipoteichoic acid or LTA, which acted on keratinocytes – the main cell types found in the outer layer of the skin.”
Blaming the Hygiene Hypothesis
Dr. Graham A.W. Rook is a professor in the department of infection at the Centre for Clinical Microbiology at the University College, London. He says the hygiene hypothesis can be blamed for:
- Severe allergic reactions;
- Gastrointestinal disorders, such as inflammatory bowel disease and Crohn’s disease; and,
- Autoimmune disorders, such as type 1 diabetes and multiple sclerosis.
Dr. Rook told U.S. News and World Report “The evidence for all this is very, very powerful … The bottom line is organisms that were present in mud, untreated water, and feces were with us right from the start of humanity.”
Exposure to these organisms trained our immune systems to combat infection. But walling children off from all the bacteria, microbes, and bugs means they are not developing defences against illness.
Dr. Mary Ruebush is the author of Why Dirt Is Good. She says that if children play in an environment occupied by bacteria their systems will develop “immune responses, which will be necessary for protection, but it also plays a critical role in teaching the immature immune response what is best ignored.”
According to the University of Nebraska “There are more organisms in a gram of soil than there are human beings on this Earth!”
Geophagia is a condition that causes people to eat soil; it can cause serious health problems.
On the impoverished island of Haiti people make cakes out of mud, occasionally mixed with salt and butter, which are called bonbons par terre. Although they have no nutritional value, the bonbons par terre are eaten to ward off the pangs of hunger.
“Babies Know: A Little Dirt Is Good For You.” Jane E. Brody, New York Times, January 26, 2009.
“The Trouble with Germ-free Bubbles.” Tom Brady, New York Times, November 23, 2013.
“Dirt Can Be Good for Children, Say Scientists.” BBC News, November 23, 2009.
“Commensal Bacteria Regulate Toll-like Receptor 3-Dependent Inflammation After Skin Injury.” Nature Medicine, published online November 22, 2009.
“Children Should be Allowed to Play in the Dirt Because Being too Clean Can Impair the Skin’s Ability to Heal Itself, New Research Suggests.” Murray Wardrop, The Telegraph, November 23, 2009.
“A Little Dirt May Be a Good Thing.” Dennis Thompson, U.S. News and World Report, September 9, 2011.
“Soil Biota.” University of Nebraska, undated.