Itching to know: the Microbiome, Allergic Disease, and Antimicrobial Chemicals.

purpose of reviewAntimicrobial compounds are pervasive consumer product additives that have been linked to allergic disease outcomes. Human-affiliated microbiomes may induce susceptibility or confer resilience to antimicrobials, or may be a mechanistic link between antimicrobials and allergy. In this review we summarize what is known about the connections between antimicrobials, microbiomes, and allergic disease states in children. RECENT

findingsOur review highlights studies on triclosan, a legacy antimicrobial, while pointing to the need for more research on parabens and quaternary ammonium compounds (QACs), which have continued widespread use in the United States. We found evidence that childhood triclosan exposure is linked to eczema, allergic rhinitis, and asthma, and the few studies of parabens and QACs also found associations with allergy outcomes. Microbiomes in the gut and airways, on skin, and potentially in human milk are also linked to allergic outcomes. Together these findings provide evidence that antimicrobials and microbes may interact in their associations with allergy, but most studies have not looked at microbes as mediators or modifiers of these associations. While the existing evidence of associations among antimicrobials, microbiomes, and allergic disease is compelling, additional epidemiologic and mechanistic studies are needed to elucidate the nature and directionality of these associations.