New health concerns about common additives to carpet fibers

James Vallette | July 08, 2015 | Materials

Public health experts are sounding new alarms about two types of chemicals that are applied to carpet fibers: perchlorate anti-static treatments and perfluorochemical stain repellents.

  • Perchlorate anti-static treatments

Carpet manufacturers often add anti-static (antistat) treatments to carpet fibers, in order to prevent the buildup of electrical charges. Carpet manufacturers have not typically disclosed the presence of these fiber additives, but sometimes clarity can be found upstream, from chemical manufacturers such as BASF. The world’s largest chemical company sells a line of antistats called Irgastat P. BASF’s product brochure recommends using Irgastat P on polypropylene carpet fiber. (1) A BASF material safety data sheet for Irgastat P22 states that this treatment contains sodium perchlorate (CAS no. 7601-89-0) (2)

The US EPA has identified sodium perchlorate as an “emerging contaminant,” due to its growing presence in drinking water and its potential to disrupt the development of children.  “At high enough exposures, perchlorate can interfere with iodide uptake into the thyroid gland,” the agency warns. “Thyroid hormones are critical for normal growth and development in fetuses, infants, and young children.” (3)

Tom Neltner, Chemicals Policy Director of the Environmental Defense Fund, has long sought federal restrictions on perchlorates in other consumer products, like food packaging. “This is a real concern since it is so persistent in the environment and potentially harmful to children’s development, especially since babies and toddlers crawl all over these fibers,” he told the Healthy Building Network.

Not all anti-static treatments for carpets are based on perchlorates. Interface, for example, uses potassium formate in its European production. (4)

Neltner suggested that carpet companies disclose the ingredients of all carpet fiber additives, and that federal agencies evaluate the likelihood of perchlorate in the carpet being rubbed off especially for a crawling infant.

  • Perfluoroalkyl substances (PFASs)

Historically, the North American carpet industry used  perfluorooctane sulfonic acid and perfluorooctanoic acid (PFOS and PFOA, C-8) in stain blocker treatments. According to industry sources, that was eliminated from US production by 2008. In their place, companies are using mixtures of shorter-chain length PFCs, mainly perfluorohexanoic acid (PFHXA, C-6) and perfluorobutanoic acid (PFBA, C-4).

This is an emerging case of so-called regrettable substitution, meaning that manufacturers have invested in an alternative that in a few years’ time has come under scrutiny of its own.

Public health scientist Arlene Blum, a leader in the movement to eliminate halogenated flame retardants from building insulation, considers these stain repellants to be another high priority chemical class.(5) In a joint statement published last month in Environmental Health Perspectives, Blum and over 200 other scientists said consumers should, “whenever possible, avoid products containing, or manufactured using, PFASs.” They assert:

“Although some of the long-chain PFASs are being regulated or phased out, the most common replacements are short-chain PFASs with similar structures, or compounds with fluorinated segments joined by ether linkages. While some shorter-chain fluorinated alternatives seem to be less bioaccumulative, they are still as environmentally persistent as long-chain substances or have persistent degradation products. Thus, a switch to short-chain and other fluorinated alternatives may not reduce the amounts of PFASs in the environment. In addition, because some of the shorter-chain PFASs are less effective, larger quantities may be needed to provide the same performance.

“We call on the international community to cooperate in limiting the production and use of PFASs and in developing safer nonfluorinated alternatives,” reads the scientists’ They said consumers should, “whenever possible, avoid products containing, or manufactured using, PFASs.” (6)

HBN profiled this class of chemicals in our 2013 report, Full Disclosure Required: A Strategy to Prevent Asthma Through Building Product Selection. We noted that children might be exposed to PFCs through hand-to-mouth transfer from treated carpets. A 2013 study of 456 Taiwanese children found that children with asthma had significantly higher concentrations of PFCs in their blood than children without asthma. (7, Dong et al (2013))

Another study, published last year, examined 1,877 US children and found that, “similar to Dong et al (2013), we estimated a significantly higher prevalence of asthma among children in association with a doubling of serum PFOA concentrations, albeit of a weaker magnitude. We believe this relationship deserves further exploration.” The scientists however found an inverse association of PFOS and asthma. (8)

Both studies noted the lack of research in this area. Much more exploration is needed about the role all PFCs play in asthma development and their exposure pathways, especially for children crawling on carpet.

Unfortunately, most carpets on the market contain PFAS stain repellants. Manufacturers should eliminate the non-essential use of these substances.

When companies take proactive action to protect childrens’ health (see Home Depot’s recent stance on phthalates in vinyl flooring), they earn great goodwill from an informed marketplace. As Bill Walsh, HBN’s executive director, said in 2010, “One thing that distinguishes a truly sustainable company is a commitment and ability to get ahead of the emerging science and innovate its products to new levels of environmental and health performance.” (9)

The carpet industry has responded to other challenges, and we look forward to another round of health-based innovation.




(4) Mikhail Davis, Interface, personal communication, July 8, 2015. Note: Potassium formate is not a human health hazard according to the 60+ authoritative lists used in our Pharos Project. However, it is a derivative of potassium cyanide, a Proposition 65 listed carcinogen.