For several years, one hypothesis behind the increase in allergies has been the ‘hygiene theory.’ This suggests that in western societies, children are exposed to fewer germs and bacteria, and that this lack of exposure can actually lead to a weaker immune system or one that identifies harmless substances as dangerous, thus causing an allergic reaction. An initial study at Johns Hopkins Children's Research Center, backed by the National Institute of Health has taken the hygiene theory and sought determine if there are any links between the use of antibacterial/antimicrobial personal care products and an increase instance of allergies.

_Starting with urinary levels of chemicals common in antibacterial soaps, mouthwashes, and toothpastes, like triclosan and parabens, researchers compared these to increased levels of IgE antibodies in the blood (elevated levels of which are common in those with allergies). What they found was that with elevated levels of triclosan and propyl and butyl parabens, there was also an increase in specific allergen antibodies, specifically those antibodies associated with respiratory and food allergens. These results were also more specific to male children.

_The parabens that were associated with higher levels of allergen antibodies are common preservatives used in a variety of personal care products. Triclosan is a chlorine based compound very common in antibacterial and antifungal soaps and toothpastes.

_While this study is by no means conclusive, nor does it show that these substances cause allergies, it does demonstrate the need for further research to refine the link between the commonly used compounds and the increasing rates of allergies in western societies.

_An abstract of the article can be found here.

_Author: Kevin Gilmore