Exposure to Antibacterials May Predispose to Allergies

Lara C. Pullen, PhD

June 20, 2012

June 20, 2012 — Exposure to the common antimicrobials triclosan and parabens was significantly associated with allergic sensitization, according to a recent study. The concentration-dependent association was found between the antimicrobials and aeroallergen and food sensitization. Both triclosan and parabens are endocrine-disrupting compounds (EDCs).

Jessica H. Savage, MD, from the Johns Hopkins Division of Allergy and Clinical Immunology, Baltimore, Maryland, and colleagues presented the results of an analysis of existing data from a national health survey in an article published online June 18 in the Journal of Allergy and Clinical Immunology. The authors used the large, nationally representative sample to investigate the relationship between EDCs and atopy. Urinary EDC levels were used as a biomarker of exposure.

The authors used data from the 2005 to 2006 National Health and Nutrition Examination Survey, which included a total of 10,348 patients, of whom 859 were children aged 8 to 16 years with complete data for the analysis of EDC levels. Aeroallergen and food sensitization were defined by the presence of at least 1 positive (≥0.35 kU/L) specific immunoglobulin E (IgE) level to an aeroallergen or food.

After adjusting for age, sex, race/ethnicity, urinary creatinine level, and income, the investigators determined that the odds of aeroallergen sensitization significantly increased with the level of triclosan and propyl and butyl parabens. Comparing the third vs the first tertile of urinary triclosan, the adjusted odds ratio (OR) for aeroallergen sensitization was 1.73 (95% confidence interval [CI], 1.11 - 2.69; P = .02). Similarly, the adjusted OR for propyl paraben was 2.04 (95% CI, 1.12 - 3.74; P = .02), and for butyl paraben it was 1.55 (95% CI, 1.02 - 2.33; P = .02).

The authors found that the increased risk for sensitization was most pronounced for men. There was no association between EDCs and a history of atopic asthma, wheeze, or total IgE level.

The authors acknowledge the limitation inherent in a retrospective, cross-sectional study. The cross-sectional study is also limited by the possibility that patients with allergy may be more likely to use products containing triclosan and parabens.

The 'Flip Side of the Hygiene Hypothesis'

Mark Holbreich, MD, FAAAAI, from Allergy and Asthma Consultants in Indianapolis, Indiana, spoke with Medscape Medical News about the article. "I think what's interesting is that it continues to support the idea that what we are exposed to early in life affects the development of allergies," Dr. Holbreich said. Previous cross-sectional and prospective epidemiological studies have demonstrated a relationship between bacterial flora and allergic disease.

Although acknowledging that the current study is preliminary, Dr. Holbreich was intrigued by the "flip side of the hygiene hypothesis." He explained that the traditional understanding of the hygiene hypothesis is that certain populations of children are protected from allergies. Typically, these protected children are characterized as children from farms who may be exposed to a wider variety of bacterial flora. Investigators acknowledge that this farm effect is likely the result of a combination of factors.

The hygiene hypothesis drives the question: Why are certain groups of children more protected and other children more vulnerable to allergies? Although the current understanding is that children with allergies are not having critical biological exposures, this article raises the possibility that children with allergies may be having chemical exposures that are creating a vulnerability to an allergic response, Dr. Holbreich said.

The study was supported by the National Institutes of Health. One author has consulted for Merck/UBC, has received grants from the National Institutes of Health, and has received payment for lectures and travel from Indoor Biotechnologies. One author has consulted for the Asthma and Allergy Foundation of America, has provided expert witness testimony for the National Institutes of Health, and has received royalties from UpToDate. One author has received grants from the National Institutes of Health. Dr. Savage and Dr. Holbreich have disclosed no relevant financial relationships.

J Allergy Clin Immunol. Published online June 18, 2012. Abstract

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