The Dirt On Antimicrobials

Bill Walsh | October 15, 2014 | Materials

The infusion of antimicrobial materials into building products is on the rise.  Manufacturers now routinely add substances such as nano-silver and the pesticide triclosan to paints, tiles and grouts, carpets, solid surfaces, faucets, elevator buttons and toilet seats.  The dirty truth is: they do not make people healthier. They do cause environmental harm throughout their lifecycle. And their overuse, like the overuse of antibiotics, may contribute to the evolution of microbes that are more resistant to our known antimicrobial defenses.

The authoritative evidence could not be clearer. One of the most widely used antimicrobials is triclosan, which is sold under trade names such as Microban and BioFresh. The Centers for Disease Control and Prevention (CDC) established its position on these antimicrobials in 2003 after a comprehensive study of infection control practice concluding: “No evidence is available to suggest that use of these [antimicrobial] products will make consumers and patients healthier or prevent disease. No data support the use of these items as part of a sound infection-control strategy.”[1]  Kaiser Permanente similarly concluded in a December 2006 position statement that “[w]e do not recommend environmental surface finishes or fabrics that contain antimicrobials for the purpose of greater infection control and the subsequent prevention of hospital acquired infections.” [2]   Kaiser Permanente removed triclosan products from all of their facilities in 2010, and after a 2013 review continued this policy. It cited the lack of evidence of direct association between antimicrobial surfaces and reduced patient infection rates and concerns about bacterial resistance and other environmental problems.

Last July, the Canadian Environmental Law Association and Clean Production Action conducted an in-depth “GreenScreen” assessment of triclosan. They concluded that it is highly toxic in humans, possesses endocrine system-disrupting properties and is highly toxic to organisms living in aquatic environments. The World Health Organization included triclosan in its 2013 state-of-the-science report on endocrine-disrupting chemicals.[3] The Centers for Disease Control found triclosan in 75% of Americans tested, with levels rising from 2003 through 2010.[4] Doctors from Johns Hopkins concluded in 2012 that these levels of triclosan in the human body "were significantly associated with allergic sensitization."[5] Under certain conditions, triclosan can break down in the environment into a group of dioxins – a class of chemicals known as potent carcinogens and endocrine disrupters.[6] Additionally, Pharos Project research into triclosan process chemistry found dioxin residuals as a common contaminant in this antimicrobial.[7] The Tandus company, which does not use antimicrobials in their carpet, provides this helpful list of authoritative sources advising against the practice.

One of the emerging concerns with the unprecedented infusion of antimicrobials into all sorts of products is that in the long term they could do more harm than good to public health. Like the overuse of antibiotics, the overuse of antimicrobials could give rise to resistant bacteria. Last June, the Environmental Working Group documented the growing body of scientific data on this point in comments filed with the Food and Drug Administration (FDA).[8] 

The new emphasis on improving human health in the green building movement is creating new opportunities to market antimicrobial products to unsuspecting consumers in a growing number of product categories. But the evidence is clear that the use of triclosan and other antimicrobials provide no additional human health benefits, and indeed may present significant dangers both to human health and the environment.  The one category they should be kept out of is green and healthy buildings.

Antimicrobials used in building materials listed in the Pharos Project

Antimicrobial CASRN Related Building Materials
Benzisothiazolin- 3-one (BIT) 2634-33-5 Paints, adhesives
Didecyl dimethyl ammonium chloride (DDAC) 7173-51-5 Wood flooring
Diiodomethyl p-tolyl sulfone 20018-09-1 Paint, Ceramic tile, Wood flooring
Hexamethylenetetramine 100-97-0 Paint
Kathon 886 (CIT/MIT mixture) 55965-84-9 Paint
Methylchlorothiazolinone (CIT, CMIT) 26172-55-4 Paint
Methylisothiazolinone (MIT) 2682-20-4 Paint
N-octadecyldimethyl(3-(trimethyoxysilyl)propyl) ammonium chloride 27668-52-6 Ceiling panels
Silver (nano) 7440-22-4 Adhesives, Grouts, Ceramic tile, Toilet seats
Silver sodium hydrogen zirconium phosphate 265647-11-8 Carpet backing
Silver zinc zeolites 130328-20-0 Adhesives, Grouts, Ceramic tile, Toilet seats
Triclosan 3380-34-5 Paints, Carpets, Engineered wood flooring, Ceramic tile
Zinc Pyrithione 13463-41-7 Carpet adhesive, Flooring adhesive, Paint, Ceiling panels, Textiles, Carpet backing, Resilient flooring

Table © Healthy Building Network, 2014

Pharos subscribers may reference the current list of antimicrobials known to be used in building products.


[1] Centers for Guidelines for Environmental Infection Control in Health-Care Facilities Recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee (HICPAC)


[2] Kaiser Permanente,” Evaluation of Antimicrobial Property Claims in Finishes and Fabrics," December 1, 2006. (


[4] See discussion, Full Disclosure Required: A Strategy to Prevent Asthma Through Building Product Selection, pp. 35-36, footnote 97.

[5] See discussion, Full Disclosure Required: A Strategy to Prevent Asthma Through Building Product Selection, pp. 35-36, footnote 96.



[8] See