Antimicrobial compound associated with allergies
By Robin Arnette
Your typical morning routine may include bathing with soap, cleaning your teeth with toothpaste and mouthwash, and topping off your hygiene regimen with deodorant. According to a recent study, though, an active ingredient in some of these products may impact your respiratory health, by promoting the development of allergies and causing inflammation in the mucous lining of the nose, also known as rhinitis.
Researchers from NIEHS, Norway, and the Centers for Disease Control and Prevention found the link, after measuring levels of triclosan, a synthetic antimicrobial chemical, in urine samples from Norwegian children. The authors published their paper (http://www.ncbi.nlm.nih.gov/pubmed/23146048) online Nov. 12 in the journal Allergy, and say their findings replicate those of another study (http://www.ncbi.nlm.nih.gov/pubmed/22704536) that used American children participating in the National Health and Nutrition Examination Survey (NHANES). Since these reports found an association between triclosan and the occurrence of allergic sensitization in two different populations, the researchers feel confident the relationship is genuine.
“Our work and the NHANES research found no association with asthma, but we have data suggesting that triclosan is connected to upper respiratory symptoms,” said Randi Bertelsen, Ph.D., lead author and visiting fellow in the NIEHS Genetics, Environment, and Respiratory Disease Group led by Stephanie London, M.D., Dr.P.H. Bertelsen took a two-year sabbatical from her post at the Norwegian Institute of Public Health to do research at NIEHS. She said this paper is the first to measure levels of triclosan exposure in any population or age group in Norway.
London is a co-author on the article and emphasized the importance of this work by pointing out that triclosan doesn’t just show up in personal products.
“It also appears in many other consumer goods, such as toys, plastic kitchen utensils, clothing, and some hand sanitizers,” London said. “Because of its prevalence in everyday items, we have to understand how it affects us.”
Bertelsen explained that the 623 Norwegian children used in the cohort have been followed since birth. At age 10, the youngsters received two days of extensive clinical evaluation at Oslo University Hospital, undergoing allergy skin prick tests and lung function assessments on a treadmill, and providing urine and blood samples. The research team sent the urine samples to the Centers for Disease Control and Prevention to measure the amounts of triclosan.
The results determined that children with allergic sensitization and rhinitis had the highest levels of triclosan in their urine. Since triclosan doesn’t stay in the body very long, 1-2 days according to Bertelsen, she and others think the elevated levels come from continued use of certain products.
“It’s believed that very little actually goes through the skin, and that the mucosa in your mouth is where everything is absorbed,” Bertelsen said. “If you like one kind of toothpaste, you’re more likely to consistently use the same brand.”
Changing the flora and fauna
The exact mechanism of how triclosan leads to allergy is unknown, but Bertelsen offered a possibility. She said triclosan kills some bacterial strains, but not all. As a result, it changes the bacterial composition in the intestine, skin, and mouth. The ratio between good and bad bacteria in the gut may be especially important. She said other studies have examined the intestinal biota in children with and without allergies and found that the microbial composition differs between the two groups.
Bertelsen plans to continue examining the triclosan-allergy connection. She said other research groups have measured triclosan in breast milk from Swedish mothers and, since Norwegian mothers tend to breastfeed their babies during the first 4-6 months of life, she and her colleagues plan to follow up the Swedish findings with a study of triclosan and allergy development in Norwegian infants. The research team has already collected urine from the newborns and will follow up as they age.
Citation: Bertelsen RJ, Longnecker MP, Lovik M, Calafat AM, Carlsen KH, London SJ, Lodrup Carlsen KC. (http://www.ncbi.nlm.nih.gov/pubmed/23146048) 2012. Triclosan exposure and allergic sensitization in Norwegian children. Allergy; doi:10.1111/all.12058 [Online 12 November 2012].