What’s new in stain repellents?

10 01 2017

We haven’t talked about stain repellents for a few years (we last published a blog on the subject 4 years ago) and think it’s time to revisit the topic because of all the claims that companies are making about “safe” stain repellents.

Here’s why stain repellents are simply doing us no good:  All stain repellent finishes used in textiles are based on fluorotelomer chemistry – which means it pertains to chemicals which become  perfluorocarbons (PFCs) when they are released into the environment.   PFC’s  break down in the body and in the environment to  Perfluorooctanoic acid (PFOA), Perfluorooctanyl sulfate (PFOS) and similar chemicals.  These are among the most persistent synthetic chemicals known to man. Scientists noticed that PFOS  was showing up everywhere: in polar bears, dolphins, baby eagles, tap water and human blood. So did its cousin PFOA.    These two man-made perfluorochemicals (PFOS and PFOA) don’t decompose in nature. They kill laboratory rats at higher doses, and are toxic to humans, with health effects ranging from birth or developmental effects, to the brain and nervous system, immune system (including sensitization and allergies) and some forms of cancer.  Once they are in the body, it takes decades to get them out – assuming you are exposed to no more. According to Our Stolen Future, the “PFOS story is likely to emerge as one of the apocryphal examples of 20th century experimentation with widespread chemical exposures: prolific use and almost no testing for safety, until unexpectedly and almost serendipitously, it is discovered as a contaminant virtually everywhere. And as is often the case in these stories, the company producing PFOS products possessed information hinting at its risks but chose not to share their data with regulators or the public for years.”

Every American who has been tested for these chemicals have these hyper-persistent, toxic chemicals in their blood. A growing number of researchers believe that fabric-based, stain-resistant coatings, which are ubiquitous, may be the largest environmental source of this controversial chemical family of PFCs.  So now you will find companies advertising that they can provide stain repellents that “are free of harmful levels of” PFOS (perfluorooctane sulphonate) or PFOA (perfluorooctanoic acid).  What does that mean?

The PFC family is a group of man-made chemicals created using perfluoroalkyl acids (PFAA), all of which have a carbon backbone, with atoms of fluorine attached to them.  The PFAA’s are known as C4 – C14:   the numbers denote how many carbon atoms are present.  Those with 8 or more carbon atoms are known as the “long-chain” PFC’s;  PFOS and PFOA are two of the most common C8s.  Those with fewer than 8 carbon atoms are called “short-chain” PFCs.  The carbon-fluorine bonds in these chemicals are very, very strong and are resistant to high temperatures, acidic and alkaline solutions, and other environmental factors. In general, the longer the carbon chain, the more potent and persistent the chemical. The same chemistry that makes these chemicals so potent and useful also means they stick around for a long time in the environment and have the potential for wide-ranging and long-term health and environmental effects.

In January 2006, the U.S. Environmental Protection Agency (EPA) approached the eight largest fluorocarbon producers and requested their participation in the 2010/15 PFOA Stewardship Program.  They wanted these manufacturers to commit to reduce PFOA and related chemicals globally in both facility emissions and product content by 95% by 2010, and 100% by 2015. Although the amount  of PFOA in finishing formulations has been greatly diminished and continues to go down, even parts per trillion are detectable.

So finishing formulators continue to evaluate new materials which can eliminate PFOA while maintaining performance – but a solution is still over the horizon.  One critical piece in this puzzle is that PFOA is also produced indirectly through the gradual breakdown of fluorotelomers – so a stain resistant finish may be formulated with no detectable amounts of PFOA yet STILL produce PFOA when the chemicals begin to decompose.

Since the EPA mandated that textile treatments can no longer contain these specific compounds, the industry is now using “short-chain” PFCs  – C6 and C4 chemistries.  These chemicals are considered safer because they are not as persistent or bioaccumulative as C8 – but there is little human data to support these contentions.  Because these chemicals haven’t received as much scrutiny as their cousins, environmentally aware designers may wonder if we are substituting the devil we don’t know for the devil we know.

3M, which produces Scotchgard, was the first company to switch to the new C4 chemistry by using perfluorobutane sulfonate (PFBS).  According to 3M, the results show that under federal EPA guidelines, PFBS isn’t toxic and doesn’t accumulate the way the old chemical did. It does persist in the environment, but 3M concluded that isn’t a problem if it isn’t accumulating or toxic. PFBS can enter the bloodstream of people and animals but “it’s eliminated very quickly” and does no harm at typical very low levels, said Michael Santoro, 3M’s director of Environmental Health, Safety & Regulatory Affairs.

But it’s also less effective, so more of the chemical has to be used to achieve the same result.  The smaller the fluorocarbon, the more rapidly it breaks down in the environment.  Unfortunatley, the desired textile performance goes down as the size of the perfluorocarbon goes down.  Now most textiles are finished with C6 chemistry, which produces a by-product called PFHA (perfluorohexanoic acid), which  is supposed to be 40 times less bioaccumulative than PFOA.  “C6 is closest chemically to C8, and it contains no PFOA. It breaks down in the environment – a positive trait – but it doesn’t stick as well to outerwear and it doesn’t repel water and oil as well as C8, which means it falls short of meeting a vague industry standard, as well as individual company standards for durability and repellency.”

PFCs are available as branded products, such as Crypton Green, or generic, unbranded treatments sold through fabric finishers.   Nanotechnology is one way to increase the performance of a fabric; Nano-Tex, Nano-Sphere and GreenShield all use C6 chemistry that is engineered using nanotechnology.

An aside about Crypton Green:  Crypton Green uses an immersion bath of C6 PFCs and what they call “silver ion technology”.  After heat curing, the fabrics are then coated twice with an acrylic-based backing that contains stain blockers and biocides.  This is bad for human health in so many ways:

  • The key ingredient of acrylic fiber is acrylonitrile, (also called vinyl cyanide). It is a carcinogen (brain, lung, bowel and breast cancers) and a mutagen, targeting the central nervous system.  According to the Centers for Disease Control and Prevention, acrylonitrile enters our bodies through skin absorption, as well as inhalation and ingestion.  
    • o Acrylic manufacturing involves highly toxic substances which require careful storage, handling, and disposal. The polymerization process can result in an explosion if not monitored properly. It also produces toxic fumes. Recent legislation requires that the polymerization process be carried out in a closed environment and that the fumes be cleaned, captured, or otherwise neutralized before discharge to the atmosphere.
    • o Acrylic is not easily recycled nor is it readily biodegradable. Some acrylic plastics are highly flammable and must be protected from sources of combustion.
    • The CDC has concluded that there is little evidence that biocides and antimicrobials (including silver ion technology) are effective in controlling disease and infection.   All manufacturers claim that their antimicrobials are safe for humans – but healthcare giant Kaiser Permanente no longer specifies carpet or textiles with  antimicrobials.

Back to our subject:  The companies that make these new C6 treatments tout the safety of the new short-chain PFC, yet the Cradle to Cradle program no longer certifies any products which contain PFCs – of any number.  By contrast, Chrstopher Lau, Ph.D., a leading biologist at the EPA, says ”what we’ve found is that short chains don’t have the PBT problems the longer chains have—they might be ‘P’ (persistent) but they are not ‘B’ (bioaccumulative) and definitely not ‘T’ (toxic)”.  It may be too soon to write off bioaccumulation and toxicity altogether, though, according to Lau. He agrees that short-chain PFCs are not as bioaccumulative as C8s, but he cautions that there is little human data to draw other conclusions.

Given the fact that, despite industry assurances that the C6 chemistry is not toxic or bioaccumulative, it is nevertheless persistent in the environment.  And given the number of times the EPA has failed to protect consumers  – most recently regarding Monsanto’s Roundup (which the World Health Organization has deemed a “probable carcinogen”) – I think I’d rather err on the side of not putting a substance (such as C6, which according to the experts, needs more study to determine toxicity) on my sofa.

That one stain repellant which is NOT based on fluorotelomer chemistry? It’s an Oeko-Tex certified stain repellent which is based on silicon dioxide (SiO2). Silicon dioxide is recognized by the FDA as a safe food additive. The second component of this stain repellent is the use of nanotechnology. Since we’re in the dawn of the nano world, we don’t know yet what nanoscience will grow up to be. If you can accept the nano portion of the stain repellent, the product is called Nano4Life (http://www.nano4life.co).



One response

10 01 2017

you are stars! can I share this (or parts) in my AGiR! blog?? best to you in 2017! RA

*** Rachel Aronoff, PhD Directrice Scientifique et Présidente AGiR! (www.genomicintegrity.org) Action pour l’intégrité Génomique via la Recherche!


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