Antibacterial ingredients like triclosan in soap and toothpaste increase allergy risk in kids

New research funded by the US National Institutes of Health (NIH) suggests level of exposure to antibacterial ingredients in personal hygiene products correlates with a child's risk for respiratory and food allergies.

Scientists from Johns Hopkins Children's Center used data from a US national health survey of 860 children, aged 6 to 18, to examine the association between urinary levels of antibacterials and preservatives found in soap, toothpaste, mouthwash and other personal care products and the presence of IgE antibodies in the children’s blood.

The presence of IgE antibodies to specific substances such as pollens or foods are a sign that an individual may be allergic to these substances, or at increased risk for subsequently developing such an allergy. Previous research, notably a study conducted by researchers at the University of Michigan School of Public Health, has shown that widespread use of antibacterial agents such as triclosan and added to personal care products to kill germs may be leading to an increase in allergies in kids; a finding the scientists said supports the Hygiene Hypothesis.

The Johns Hopkins researchers focused on seven chemicals known to be endocrine-disrupting compounds (EDCs) in animals i.e. they mimic or block the action of hormones. These EDCs are also known to alter the way the immune system functions, hence the connection with allergy risk.

The EDCs investigted in this study were triclosan, bisphenol-A (BPA), benzophenone-3, and propyl, methyl, butyl, and ethyl parabens. Triclosan is found in soaps and hand sanitizers, toothpaste, and mouthwash, while parabens are used in food, medications, and cosmetics.

The investigators at Johns Hopkins found that out of the seven compounds tested only triclosan, propyl paraben, and butyl paraben were associated with an increased risk of allergy. All three of these chemicals have antibacterial properties whereas the other chemicals do not.

Specifically the study results showed that the risk of sensitization to aeroallergens (e.g. pollen, dust, animal dander) in both boys and girls significantly increased in proportion to the concentrations of  triclosan, propyl paraben, and butyl paraben in their urine.

Additionally, the risk of food sensitization significantly increased with the level of urinary triclosan among the boys in the study.

The most important finding was that only those chemicals used as antimicrobials increased allergy risk. Those used as preservatives (e.g. bisphenol-A) did not; although these have been shown to have their own health dangers as EDCs.

Lead investigator Corinne Keet, MD, MS, an allergist at Johns Hopkins Children's Center said: "This finding highlights the antimicrobial properties of these agents as a probable driving force behind their effect on the immune system."

The results of this latest study go a long way to confirm previous results from the University of Michigan and others. They suggest that in trying so hard to keep kids safe from germs and infectious diseases we are inadvertently increasing the chances that they will develop allergies. As the Hygiene Hypothesis postulates, it may be that a certain level of early childhood exposure to dirt and germs is required to enble the immune system to develop strong and balanced defenses.

Parents naturally want to protect their kids from harm or distress of any kind but this study adds to the body of evidence now showing that using antibacterial products may not be the best way to do this. 

Source: Savage JH, Matsui EC, Wood RA, Keet CA (2012) Urinary levels of triclosan and parabens are associated with aeroallergen and food sensitization Journal of Allergy and Clinical Immunology doi: 10.1016/j.jaci.2012.05.006