Triclosan is a common antimicrobial agent that accumulates in our bodies and has been linked to hormone disruption and the emergence of bacteria resistant to antibiotics and antibacterial products. Along with its negative health effects, triclosan also impacts the environment, ending up in lakes, rivers and other water sources, where it is toxic to aquatic life.
Products That May Contain Triclosan
Triclosan is found in a wide variety of antibacterial soaps and detergents, as well as in many deodorants, toothpastes, cosmetics, fabrics and plastics. Triclosan was initially developed as a surgical scrub for medical professionals, but in recent years it has been added to a host of consumer products, from kitchen cutting boards to shoes, in order to kill bacteria and fungus and prevent odors. However, triclosan has proved to be both dangerous and unnecessary—in 2005, the FDA found no evidence that antibacterial washes containing triclosan were superior to plain soap and water for protecting consumers from bacteria.
There is evidence that triclosan is an endocrine disruptor and impacts thyroid function and thyroid homeostasis. One recent study found that triclosan had an effect on thyroid hormone concentrations (i), and another showed that triclosan interacted with androgen and estrogen hormone receptors (ii).
Since 2000, a number of studies have found microorganisms that are resistant to triclosan, and there is mounting evidence linking the use of triclosan with the promotion of bacteria resistant to both antibiotic medications and antibacterial products (iii, iv). Triclosan-resistant strains of microorganisms such as E-coli and Salmonella have already been identified (v, vi, vii). Studies indicate that use of triclosan provides a suitable environment for the emergence of antimicrobial drug-resistant bacteria, even at the low concentrations found in many FDA-regulated products and cosmetics.
Because triclosan's mode of action and target site in the bacteria is similar to antibiotics, there are concerns that bacteria that become resistant to triclosan will also become resistant to antibiotics. A recent report by the European Commission's Scientific Committee on Consumer Safety determined that even low concentrations of triclosan can trigger antibiotic resistance in bacteria (viii).
Accumulation of triclosan in our bodies and in wildlife
Triclosan is lipophilic, meaning that it accumulates in fatty tissues. Studies have found concentrations of triclosan in three out of five human milk samples as a result of exposure through personal care products containing triclosan (ix, x). Triclosan has also been found in umbilical cord blood of infants (xi). These results raise concerns for the developing fetus during vulnerable periods of development, and make the bioaccumulative and endocrine-disruptive potential of triclosan more even more alarming.
Triclosan has been found in the bodies of most Americans, with researchers from the Centers for Disease Control and Prevention identifying triclosan in the urine of 75 percent of the U.S. population (xii). The latest CDC data show a 40 percent jump in triclosan levels in people over a two-year period (xiii).
Since the majority of the products that contain triclosan are eventually washed down consumers’ residential drains, high levels of triclosan are accumulating in water systems and negatively impacting the environment. Triclosan is toxic to algae (because algae is a first-step producer, the destruction of algae is particularly disruptive to aquatic ecosystems) and there is evidence that triclosan is accumulating at high levels in fish and other aquatic life (xiv).
i. Zorrilla, L., et al (2009). The effects of Triclosan on Puberty and Thyroid Hormones in Male Wistar Rats. Toxicological Sciences. 107(1) 56-64.