Taken together, many studies now demonstrate that triclosan is certainly not the safe and healthy bacteria-fighting hand soap ingredient we once might have assumed.
>Triclosan: Toxic to people and the environment
CDC research on a broad cross-section of the population detected triclosan in the urine of 75% of 2,517 Americans (Calafat 2007). Higher levels of triclosan were typically found in higher income participants. An earlier study spearheaded by the Mount Sinai School of Medicine found triclosan in the urine of 61% of 90 girls age 6 to 8 (Wolff 2007).
Triclosan tends to bioaccumulate (Samsøe-Petersen 2003), or become more concentrated in the fatty tissues of humans and other animals. As a result, this chemical has been detected in human breast milk, and in blood samples as well (Adolfsson-Erici 2002; TNO 2005; Allmyr 2006a,b; Dayan 2007). Higher levels of triclosan in blood and breast milk are linked to use of body care products containing triclosan (Allmyr 2006b).
Lab studies link triclosan to cancer, developmental defects, and liver and inhalation toxicity. A secret study by Colgate scientists revealed exposure to low levels of triclosan caused liver tumors in mice (See 1996). Colgate refuses to release this study to EPA for evaluation, though it provided it to FDA in order to ensure it could add triclosan to toothpaste and other oral care products. Based on the study summary alone, and using a controversial assumption about the way this type of liver tumor forms in mice, EPA classified triclosan as “not likely to be carcinogenic to humans” (EPA 2008). This decision flows in part from EPA’s lack of regulatory authority to demand release of Colgate’s findings, a clear indication of the need for reform of the U.S. system of chemical health protections.
EPA does have access to several other lab animal studies linking triclosan to a variety of health effects. A study linking low level maternal triclosan exposure in mice to health effects in offspring, including irregular skull development and decreased fetal weight, provides evidence that triclosan may be a developmental toxicant (MRID 43817501: citation missing from EPA 2008b). Another mouse study, involving exposures to low levels of triclosan for 28 days, documented its toxic effects on the liver (Trutter 1993). While EPA summarizes the results of these studies in its documents, the Agency seems to ignore them when assessing the risks associated with this pesticide. In contrast, EPA acknowledges the substantial inhalation risk associated with triclosan, revealed by a 21-day rat study that found signs of toxicity at all levels of exposure (MRID 0087996: citation missing from EPA 2008b).
> Triclosan may affect the thyroid and other hormone systems
A study of frogs shows that this pesticide perturbs a fundamental thyroid hormone signaling mechanism that is nearly identical to that of humans. Low levels of triclosan, in combination with thyroid hormones, triggered accelerated transformation of tadpoles into frogs (Veldhoen 2006). Triclosan, in concentrations under 1 part per billion commonly measured in U.S. streams, interfered with the timing of expression of thyroid-regulated genes that are crucial in a frog’s early development. Thyroid hormones are critical for normal growth and development of humans as well; the developing brain of a child is particularly vulnerable to damage caused by disruption of the thyroid system.
Triclosan may also disrupt other critical hormone systems. A recent lab study found the chemical to exert both estrogenic and androgenic effects on human breast cancer cells (Gee 2008). Studies of fish suggest that triclosan may have weak androgenic (Foran 2000) or anti-estrogenic effects (Matsumura 2005), while a metabolite of triclosan may have estrogenic effects (Ishibashi 2004).
> Triclosan contaminates streams and is toxic to wildlife
Scientists recently found trace levels of triclosan in 58% of 85 streams located throughout the U.S. (Kolpin 2002), the likely result of its presence in discharges of treated wastewater. The pesticide has also been detected in several aquatic species (Remberger 2002; Adolfsson-Erici 2002). The amount of triclosan in wastewater is estimated to be as much as 3 to 5 milligrams per person per day from residences alone (McAvoy 2002); in addition, substantial discharges are expected from laundries, hair salons, medical facilities, and other sites. Optimized water treatment can remove up to 95% of triclosan (Samsøe-Petersen 2003); however, EWG research confirms that some triclosan persists despite treatment and enters receiving waters (EWG/EBMUD 2007).
Triclosan is acutely toxic to several different types of aquatic life (e.g. Samsøe-Petersen 2003; Orvos 2002; Ishibashi 2004; Dussault 2008). Algae have proved to be the most sensitive organisms, but fish and invertebrates also experience adverse impacts following acute or chronic exposures to low levels of triclosan. An investigation of one algal species revealed genotoxic effects that warrant further study (Ciniglia 2005).
> Triclosan forms other dangerous compounds
Studies indicate that in surface waters, triclosan can interact with sunlight and microbes to form methyl triclosan, a chemical that may bioacummulate in wildlife and humans (Adolfsson-Erici 2002; Lindstrom 2002). A recent European study found methyl triclosan in fish, especially concentrated in fatty tissue (Balmer 2004). Few studies have probed the toxicological effects of methyl triclosan, but a recent publication reveals that the transformation product triggers acute toxic effects in the marine bacterium Vibrio fischeri at levels significantly lower than does triclosan (Farré 2008).
Triclosan also can degrade into a form of dioxin, a class of chemicals linked to a broad range of toxicities including cancer (Lores 2005). The Canadian government limits the levels of dioxins allowed as impurities in personal care products that contain triclosan. New research shows that triclosan in tap water can react with residual chlorine from standard water disinfecting procedures to form a variety of chlorinated byproducts at low levels, including chloroform, a suspected human carcinogen (Fiss 2007).
> Triclosan: One of many contaminants
Triclosan is just one of thousands of industrial chemicals in use in the U.S. today. As a pesticide, triclosan is subject to more stringent health and safety standards than many other industrial chemicals. Yet, as EPA’s flawed risk assessment makes clear, a few additional requirements do not necessarily result in chemical safety. Instead, what's needed is a new, comprehensive U.S. chemicals policy that truly protects children and other vulnerable populations from harm.
