chemical information


Chemical Class:


Found in these people:

Jessica Assaf, Erin Schrode, Asta Haman-Dicko, Hope Atkins, Rizza Alcaria, Alex Wells, Anonymous Teen 9, Anonymous Teen 20, Emma Spencer, Christa Heffron, Natalie Klapper, Sydney Blankers, Anonymous Teen 11, Sarah Oswald, Caroline Burlingame, Laurie Mittelmann, Monica Paulson, Donalin Cazeau, Jenny Gilbertson, Anonymous Teen 21, Anonymous Adult 2, Anonymous Adult 3, Anonymous Adult 4, Anonymous Adult 6, Anonymous Teen 1, Anonymous Adult 9, Anonymous Adult 12, Anonymous Adult 13, Anonymous Adult 11, Anonymous Adult 10, Anonymous Adult 14, Anonymous Adult 15, Anonymous Adult 16, Anonymous Adult 17, Anonymous Adult 18, Anonymous Adult 20, Anonymous Adult 21

Found in these locations:

San Rafael, CA; Ross, CA; San Leandro, CA; Tuolumne, CA; Manteca, CA; Washington, DC; Austin, TX; Winchester, MA; Portland, OR; San Francisco, CA; Belmont, CA; Los Angeles, CA; Palm Beach Gardens, FL; Langhorne, PA; North Caldwell, NJ; University Place, WA; Dorchester, MA; Novato, CA; Chicago, IL; Newton, MA; New York, NY; Atlanta, GA; Mountain View, CA; Stanford, CA; Palo Alto, CA; Berkeley, CA; Alamo, CA; Fallbrook, CA

Exposure routes:

Antibacterial soap, toothpaste, cosmetics, cleaning products, shoe insoles, plastic cutting boards, other antibacterial items.


Triclosan is an antibacterial agent (pesticide) found in a broad variety of everyday products, ranging from hospital and household liquid hand soap, detergents, and other sanitizing products, to toothpaste, cosmetics, and plastic items like cutting boards and shoe insoles. The popularity of antibacterial consumer products has led to increased use of triclosan (Perencevich 2001; Tan 2002). This chemical has been detected in human breast milk and blood samples (Adolfsson-Erici 2002; TNO 2005), and in the urine of 61% of 90 girls age 6 to 8 tested in a recent study spearheaded by Mount Sinai School of Medicine (Wolff 2007). A new Centers for Disease Control study on a broader 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.

Triclosan kills microbes by disrupting protein production, through binding to the active site of a critical carrier protein reductase enzyme that is essential for fatty acid synthesis. This target enzyme is present in microbes but not in humans. Though triclosan is acutely toxic to certain types of aquatic organisms (Orvos 2002), available studies do not indicate it causes cancer or birth defects in humans (Bhargava 1996). Products containing triclosan may cause skin irritation in people with a specific sensitivity (Bhargava 1996).

Triclosan has the tendency to bioaccumulate (Samsoe-Petersen 2003), or become more concentrated in the fatty tissues of humans and other animals. A recent lab study found the chemical to exert both estrogenic and androgenic effects on human breast cancer cells (Gee 2008). Studies of fish also suggest that triclosan may have weak androgenic (Foran 2000) or anti-estrogenic (Matsumura 2005) effects, while a metabolite of triclosan may have estrogenic (Ishibashi 2004) effects.

In addition, another study found that low levels of triclosan in combination with thyroid hormones triggered rapid transformation of tadpoles into frogs (Veldhoen 2006). Rather than mimicking the thyroid hormone, triclosan, in concentrations of less than 1 part per billion commonly measured in U.S. streams, appeared to make these hormones more potent. This hormone signaling mechanism is similar in frogs and humans, suggesting that triclosan could potentially disrupt the human thyroid system.

The evolving interaction between microbes and antiseptic agents has led to concern that use of some antimicrobial ingredients may provoke development of strains of bacteria resistant to disinfection. Some strains of bacteria have acquired reduced susceptibility to triclosan (McMurry 1998; Chuanchuen 2001). The identification of a triclosan-resistant bacterial enzyme suggests that resistance to this antibacterial agent may develop more readily than to other agents (Heath 2000). In addition, exposing specific bacterial strains to triclosan appears to result in selection favoring bacteria that are resistant to multiple antibiotics (Chuanchuen 2001).

The American Medical Association has advanced an official recommendation against using antibacterial products in the home due to concern about antimicrobial resistance (Tan 2002). A Food and Drug Administration panel reviewed existing research and found no evidence that households that use antibacterial products are healthier than households that use soap and water and other typical cleansing products (FDA 2005).

Scientists recently found triclosan in 58% of 85 streams across the U.S. (Kolpin 2002), the likely result of its presence in discharges of treated wastewater. The amount of triclosan in the wastwater stream is estimated to be as much as 3 to 5 milligrams per person per day from residences alone (McAvoy 2002); in addition, substantial discharges of this antimicrobial agent are expected from laundries, hair salons, medical facilities, and other sites. Water treatment can remove up to 95% of triclosan (Samsoe-Petersen 2003); however, small amounts pass through treatment plants to receiving waters.

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). 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 and furans 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).


Antibacterial agent (pesticide) in liquid hand soap, toothpaste, cosmetics, cleaning products, footwear, and plastic products labeled "antibacterial." Triclosan may disrupt thyroid hormones, and can form several chemicals with health and environmental concerns.

Triclosan has been found in 42 of the 49 people tested in EWG/Commonweal studies. It has also been found in 1,862 of the 2,612 people tested in CDC biomonitoring studies.

Top health concerns for Triclosan (References)

health concern or target organ weight of evidence
Endocrine systemlimited

Other health concerns for Triclosan (References)

health concern or target organ weight of evidence
Immune system (including sensitization and allergies)possible

Results for Triclosan

Triclosan was measured in different units for some of the studies. Overall it was found in 42 of 49 people tested in EWG/Commonweal studies. The bars below are grouped by units:

in urine

Showing results from Dateline NBC Families, EWG Study #10, cosmetic chemicals in teens, Dateline NBC Families

EWG/Commonweal results

  • geometric mean: 5.47 ug/g creatinine in urine
  • found in 25 of 28 people in the group

CDC biomonitoring results

  • geometric mean: 10.1 ug/g creatinine in urine
  • found in 1862 of 2612 people in the group
ug/g creatinine in urine 2640

Triclosan results

in blood serum (wet weight)

Showing results from EWG/Commonweal Study #7, consumer product chemicals in adults and teens, EWG Study #8, chemicals in mother and 2 children

EWG/Commonweal results

  • found in 17 of 21 people in the group

found in 17 of 21 people, but not quantified

Detailed toxicity classifications (References)

classification governing entity/references
Endocrine disruptor - suspected or limited evidenceVeldhoen, N., R. C. Skirrow, et al. (2006). "The bactericidal agent triclosan modulates thyroid hormone-associated gene expression and disrupts postembryonic anuran development." Aquat Toxicol 80(3): 217-27.
Endocrine disruptor - suspected or limited evidenceForan, C. M., E.R. Bennett, W.H. Benson (2000). "Developmental evaluation of a potential non-steroidal estrogen: triclosan." Marine Environmental Research 50: 153-156.
Skin sensitizerBhargava H., L. P. (1996). "Triclosan: Applications and safety." Am J. Infect Control 24: 209-218.
Limited evidence in humans - skin toxicityBhargava H., L. P. (1996). "Triclosan: Applications and safety." Am J. Infect Control 24: 209-218.