Medicine Clean is good, especially when it comes to fending off germs, but is there such a thing as being too clean? Perhaps. Researchers based at the University of Michigan School of Public Health report that children who overuse antibacterial soaps may be at higher risk of developing allergies.

And among adults, the scientists found that exposure to BPA, the endocrine-disrupting chemical commonly found in plastics, may trigger changes in the immune system that could affect everything from allergies to the body's ability to fight disease. (More on Time.com: Cheers! Could Hypoallergenic Wine Be on the Horizon?)

The reason for the link between antibacterial soaps and allergies has to do with the hygiene hypothesis, a theory about how the immune system develops and reacts to assaults. Some scientists believe that our society's current obsession with cleanliness — both in the form of overuse of antibacterial cleaning products, as well as an exceedingly sanitized lifestyle that keeps us isolated from most sources of germs that can make us ill — has caused our immune systems to become hypersensitive to foreign assaults of all kinds, whether harmful or beneficial.

And because younger generations have been raised in such relatively sterile and clean environments, these researchers argue, their immune systems have not been challenged sufficiently to respond to bacteria and viruses, leading them to mistakenly overreact to common proteins such as those found in foods and grasses or dust. That results in allergies.

The Michigan scientists analyzed data from a large-scale government survey known as the National Health and Nutrition Examination Survey (NHANES), between 2003 and 2006. The database included measurements of a compound called triclosan, which is commonly found in antibacterial soaps and other products such as toothpaste. When measured in the urine, says Allison Aiello, one of the authors of the paper, triclosan can serve as a marker for how “clean” an individual's environment is. Among those under the age of 18, she and her colleagues found that those who showed higher levels of triclosan were more likely to report allergies or hay fever. In fact, for every unit increase of triclosan excreted, there was a 24% greater likelihood of being diagnosed with hay fever or allergies among those younger than 18. (More on Time.com: Got Allergies? Be Careful How You Hook Up)

“It was surprising, because I wasn't sure whether we would necessarily find any relationship, since there have only been a few studies looking at triclosan and its effects on the immune system in general,” says Aiello. While she notes that the study does not confirm a causal relationship between cleaning with antibacterial products and allergies — it's possible, for example, that those with allergies may tend to use these types of products more — she stresses that data strongly suggest a need for additional research into better understanding how an exceptionally clean environment affects the immune system.

That applies to the other interesting result from the study as well, which involved the association between high levels of BPA and changes in the immune system of adults. Among the same individuals surveyed in the NHANES study, the scientists found that those with the highest levels of BPA tended to show higher levels of antibodies to a virus known as cytomegalovirus (CMV). While most American adults will have been exposed to CMV by the time they reach 65, it generally remains inert in the body and only tends to flare up during times of stress, such as when students take exams, or employees face a challenging task at work. Spikes of antibodies to CMV is a commonly used measure of the immune system under distress, and the Michigan study found that exposure to BPA could produce the same peaks in CMV antibodies that stress normally does. “The hypothesis is that BPA may be activating the immune system,” says Aiello, “but we need more research to understand what aspect of the immune system BPA is affecting since CMV is just one of many parameters of immune function that we can measure.” (More on Time.com: Halotherapy: Is Salt Treatment For Real?)

The results, while sobering, should be helpful in pointing researchers toward new areas of study to better understand how exposure to antibacterial products and chemicals such as BPA may be affecting our health. Already, some nations in Europe, for example, require warnings on products containing triclosan, alerting consumers about its potential effect on the health of children. These results may serve as the starting point for similar discussions about possible safety labeling about these compounds in the U.S.

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Read more: http://healthland.time.com/2010/12/03/can-overuse-of-antibiotic-soap-promote-allergies-in-kids/#ixzz17AZvdMdF