A 2005 study found that more than half of the American population has an allergic reaction to at least one of 10 common allergens [source: AAAAI]. Some microbiologists suspect that the emergence of the antibacterial lifestyle may be responsible.
From birth, people are bombarded by unseen microbial life, which biologists call environmental flora. These little organisms are everywhere: in dirt, on countertops, in the air and even in your own body. While some cause infection, the majority are benign. Some are even helpful, like lactobacillus, which aids in our digestion of food and kills other, harmful bacteria.
Since there are a lot more flora than there are people, the human body has developed a way of warding off infection and allergies caused by microbial life. The human body's T-helper cells generate an immunoresponse to invasions by microbes. There are two types of T-helper cells: T-H1 cells help other cells form their own defenses against microbial invaders. T-H2 cells oversee the production of antibodies, which attack and kill foreign microbes that have entered the body.
Put together, these two types of helper cells are the reason you don't die whenever someone sneezes on you or you cut your finger. They are also the reason why you don't suffer constant allergic reactions whenever you breathe.
To work correctly, these helper cells must encounter microbes and allergens. The inoculations you get as a child are actually dead or weakened strains of microbes introduced into your system that your body uses to build its defenses against other, similar strains. In a household that relies heavily on antibacterial agents, a child's immune system may not get a chance to encounter enough allergens to produce the proper antibodies and defenses against them. The antimicrobial agents used in the home will have killed most of the allergens first.
While a parent can control his or her household, he or she can't sanitize the whole world. Once a child leaves an overly santized home, his or her underdeveloped immune system will be exposed to a host of microbes and allergens.
Even resisting personal overuse of antimicrobial chemicals may not prevent you from coming in contact with them. Antibiotics may be present in the food you eat and in the water you drink.
Modern agribusinesses use antibiotics to keep their livestock healthy. These antibiotics remain in the meat from those animals that makes it to the dinner table. And runoff from livestock yards and processing plants can make its way into groundwater and other sources from which people draw water.
Should antimicrobial agents be banned? That may be a bit premature. Read the next page to find out why the jury's still out.