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Research Summary: Triclosan / Triclocarban

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Joseph G. Allen, Harvard T.H. Chan School of Public Health
Aaron Bernstein, Harvard Medical School
Lacey Klingensmith, Harvard T.H. Chan School of Public Health
Piers MacNaughton, Harvard T.H. Chan School of Public Health

What are antimicrobials?

Antimicrobials are chemicals designed to kill, or impair the growth of, microorganisms. The predominant type of antimicrobials are antibiotics, which specifically target bacteria as opposed to viruses, parasites, or fungi. In the built environment, triclosan [tri-‘kloh-san] and triclocarban [tri-kloh-‘car-ban] are two of the most widely used antibiotics. They are most commonly found in disinfectants and hand-sanitizers, but they, along with other antimicrobials, are also found in consumer products such as food containers, toys, school supplies, paint and clothes.2

Why should we be concerned about antimicrobials?

Recent surveys of the U.S. population have found that between 75-80% of American children and adults have measurable levels of triclosan in their urine.3,4,5 Triclosan has also been detected in human breast milk, amniotic fluid, and blood.2,6 The ubiquity of antimicrobials in modern society increases the likelihood that vulnerable individuals may be exposed to these chemicals through ingestion or dermal absorption. While the human body can metabolize triclosan and triclocarban relatively quickly, exposures are relatively constant. These chemicals remain persistent in the environment and enter can also enter the food chain and bioaccumulate in fish and produce.4,18,36

“Several years ago we stopped purchasing hand soaps that contain the antibacterial triclosan because it was found to be no more effective than washing with plain soap and water, and may cause hormone related health problems.”
– Kaiser Permanente Environmental Stewardship Officer

A growing body of evidence suggests that the use of antimicrobials can contribute to antibiotic resistance and antibiotic cross-resistance.2,7,8,9,10,11 As a result, it is increasingly difficult to control bacteria with antimicrobials. The results of several studies also indicate that triclosan exposure may increase allergen sensitivity and exacerbate asthma and allergic symptoms in children and adults.12,13,14,15,16,17 Triclosan may also be an endocrine-disrupting chemical based upon animal studies. In rats, exposure to triclosan has interfered with estrogen-dependent responses in females, and with testosterone concentrations in males.6,18,19,20,35 In humans, there is some evidence that environmental exposure to triclosan can adversely affect sperm quality and birth outcomes.22,23,24

Do antimicrobials in the built environment prevent the spread of infection?

Advances in hygiene have gone a long way toward advancing public health, but excessive cleanliness may do more harm than good. This concept is central to the “hygiene hypothesis” which proposes that exposure to some germs at critical stages of human development is essential to properly stimulate and develop a well-functioning immune system.25 This is supported by evidence from previous studies indicating that childhood infections are associated with lower incidence of allergic disorders.26,27,28

Although antimicrobials may be effective against many strains of bacteria and some fungi,2 they can also alter bacterial flora of the skin, mouth, and intestines.29,30 In the process of disinfection, triclosan and triclocarban can remove healthy bacteria from the body which are essential to supporting a strong, healthy immune system.1,14

No peer reviewed scientific studies have demonstrated that inclusion of antimicrobials in building materials provides a greater protection against the spread of infection over routine cleaning practices.31,32,33,34 Antimicrobial use can promote the development of resistant bacteria and the U.S. Environmental Protection Agency is currently evaluating whether the use of triclosan and triclocarban in building materials and consumer products may contribute to the spread of resistant bacteria. In addition, antibiotics such as triclosan and triclocarban cannot prevent the spread of viruses, or even many harmful bacteria which are common in hospitals.2

Based on these studies, and no evidence that they reduce disease spread over plain soap, several organizations have started to restrict their use. Kaiser Permanente, a large hospital chain, has removed triclosan from all 37 of its hospitals. Major manufacturers have also pulled back from using triclosan including Johnson & Johnson and Procter & Gamble.1,2 The World Health Organization has included triclosan among its list of potential endocrine disruptors,35 and the FDA has announced a ban on triclosan and 17 other antibiotics in soaps and body washes effective September 2017.33


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