A study conducted by the University of Michigan's School of Public Health suggests that individuals exposed to triclosan in personal care products such as soaps and cleansers or other skin care may suffer from increased allergies.
Researchers compared the amounts of triclosan found in urine with allergy or hay fever diagnoses in US adults and children over the age of 6 using data from the 2003–2006 National Health and Nutrition Examination Survey. Higher levels of triclosan in those under the age of 18 were found to correlate with increased diagnoses of allergies and hay fever. These findings were published in Environmental Health Perspectives.
The study notes that triclosan is classified as an endocrine-disrupting compound (EDC), which are believed to negatively impact human health by mimicking or affecting hormones. The researchers hypothesized that with exposure to triclosan, a young individuals' immune systems may not fully develop due to the ability of the compound to limit exposure to specific microorganisms.
The researchers reference the “hygiene hypothesis,” which argues that the developing human immune system needs exposure to microorganisms for proper stimulation of T helper cells, TH-1 and TH-2 cells. Conversely, most individuals with allergies have an imbalance in TH-1 and TH-2 cells, with more TH-2 cells that promote antibody production. The researchers postulate that during the development of the immune system, triclosan may modify immunologic responses to micro-organisms in such a way that imbalances between TH-1 and TH-2 cells are created. These T-cell imbalances may stimulate autoimmune reactions and allergies.
The researchers plan to further assess the long-term effects of triclosan in individuals to determine whether a causal relationship can be established.