Bisphenol A in textile processing?

16 12 2011

If you’ve bought baby bottles or water bottles recently, I’m sure you’ve seen a prominent “BPA Free” sign on the container.

BPA stands for Bisphenol A, a chemical often used to make clear, polycarbonate plastics (like water and baby bottles and also eyeglass lenses, medical devices, CDs and DVDs, cell phones and computers).  And though it has been formally declared a hazard to human health in Canada and banned in baby bottles in both Canada as well as the EU,  U.S. watchdog agencies have wildly differing views of BPA:  The National Toxicology Program (NTP) reported “some concern” that BPA harms the brain and reproductive system, especially in babies and fetuses.  The Food and Drug Administration declared that “at current levels of exposure” BPA is safe.

But consider this:  Of  the more than 100 independently funded experiments on BPA, about 90% have found evidence of adverse health effects at levels similar to human exposure. On the other hand, every single industry-funded study ever conducted — 14 in all — has found no such effects.  David Case made the argument in the February 1, 2009 issue of Fast Company that this is a story about protecting a multibillion-dollar market from deregulation.  But that’s beside the point  which is:    nobody disputes the fact that people are constantly exposed to BPAs and babies are most at risk.  It’s also undisputed that BPA mimics the female sex hormone estrogen, and that some synthetic estrogens can cause infertility and cancer.  If you’d like to read more about this click here.

Bisphenol A is now deeply imbedded in the products of modern consumer society.  This is important because it’s used in so many modern products (making it pretty much ubiquitous), and because it is extremely potent in disrupting fetal development. BPA contamination is also widespread in the environment. For example, BPA can be measured in rivers and estuaries at concentrations that range from under 5 to over 1900 nanograms/liter.(1)

What this all means is that most of  us live our lives in close proximity to bisphenol A.

Because it’s used to make plastic hard, I never thought it would have a place in the textile industry.  So it was with some concern that I came across articles which explain the use of bisphenol A in the manufacturing of synthetic fibers.

Producing synthetic fibers and yarns is almost impossible without applying a processing aid to the fibers during the extrusion and spinning processes.   The fibers and yarns are frequently in contact with hot surfaces, or they pass through hot ovens.  In order to withstand these extreme conditions, the yarns and fibers have processing aids or finishes applied.    This applied processing aid or ‘finish’, in addition to helping the yarns withstand extreme temperatures, also  reduces static electricity, fiber-fiber and metal-fiber friction, provides integrity to the filaments,  and altogether eases the manufacturing processes.

But because modern manufacturing equipment runs at higher speeds and subsequently at higher temperatures, the finish degrades in the high temperatures – yielding lower quality fibers –  and generates unwanted decomposition products.  These byproducts can be in the form of:

  1. Toxic and nontoxic gases which have environmental and safety issues;
  2. Liquids, which leave a sticky residue on the yarns,
  3. Or they may form a solid varnish on hot surfaces that is very difficult to remove; the presence of the varnish interferes with continuous, efficient production leading to economic losses due to equipment shutdown and product failure.

To overcome the problems caused by the degradation of finishes, several additives are introduced to prevent or delay the reactions of oxidation and degradation.  Several classes of antioxidants are typically used as these additives in these finishes.

In a study sponsored by the National Textile Center, a research consortium of eight universities, three North Carolina State University professors investigated the thermal stability of textiles, specifically with respect to the antioxidants used in the finishes.  They investigated four different antioxidants – one of which is based on Bisphenol A. (2)

So I got interested, and began a bit of poking around for other mentions of Bisphenol A in the textile industry. I found two scientific references to use of bisphenol A in the production of  polyester fabrics.  Both reported similar use of Bisphenol A as this quote,  which states:  “ a woven polyester fabric was … finished with an aqueous compound  containing 5% polyethylene glycol bisphenol A ether diacrylate for 30 min at 60° to give a hygroscopic, antistatic fabric with good washfastness.” (3)

I found that Bisphenol A is used  in the production of flame retardants, and as an intermediate in the manufacture of polymers, fungicides, antioxidants (mentioned above), and dyes.   Because it is often used as an intermediate it’s hard to pin down, and manufacturers keep their ingredients trade secrets so we often will not know – unless somebody funds a study which is published.

I have not seen any studies which report finding Bisphenol A in a finished fabric, so this may be a tempest in a teacup.  But isn’t it worth noting that this chemical, which has been found in the blood of 95% of all Americans, and which some say may be the “new lead”, can exist in products in which we previously never would have thought to look?

(1)  http://www.ourstolenfuture.org/newscience/oncompounds/bisphenola/bpauses.htm

(2) Grant, Christine; Hauser, Peter; Oxenham, William, “Improving the Thermal Stability of Textile Processing Aids”,  www.ntcresearch.org/pdf-rpts/AnRp04/C01-NS08-A4.pdf

(3)  http://www.lookchem.com/cas-644/64401-02-1.html?countryid=0


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