Smart discussion about toxics policy reform

Industry calls them super plastics. What if they’re also super dangerous?

Wherever scientists have looked – in the pristine Arctic or comfortable Marin County – they have found people and wildlife polluted with perfluorochemicals (PFCs).  PFCs are the most indestructible chemicals ever made by man, and they are all around us.  Among the most worrisome PFCs:

  • Perfluorooctanoic acid (PFOA) is a likely human carcinogen, endocrine-disrupting chemical and reproductive toxin used in the manufacture of fluoropolymers such as DuPont’s Teflon.
  • Perfluorooctanesulfonic acid (PFOS) is a persistent, bioaccumulative, cancer-causing chemical used in Scotchgard and other fabric coatings until 2000, when 3M, the only U.S. manufacturer of the chemical, accepted a voluntary agreement with the U.S. Environmental Protection Agency to phase it out.

Stumped: No-one’s sure how humans are being exposed
Over 90% of the US population has PFOA and PFOS in their blood.  The cause of this widespread contamination has been a scientific mystery.  As EPA says on its own website: “The Agency does not have a full understanding of how people are exposed to PFOA.”

Nonetheless, in January 2006, former EPA Administrator Steve Johnson initiated the 2010/15 PFOA Stewardship Program, in which the eight major companies in the industry committed voluntarily to reduce facility emissions and product content of PFOA and closely related PFCs on a global basis by 95% no later than 2010, and to work toward eliminating emissions and product content of these chemicals by 2015.

Still, no one is quite sure where PFOA and other PFCs are coming from.

Pollution with PFCs is far too pervasive globally to be attributed to obvious sources, such as spills or emissions from the relative handful of manufacturing facilities.

Fluoropolymers, on the other hand, found in stain-resistant carpeting, furniture sprays, cookware, water-resistant fabrics, food packaging, paints, cosmetics and a host of other consumer products, are a potentially major source of PFOA contamination.

EPA’s polymer exemption questioned with new science
But they have escaped any significant regulatory scrutiny because of a long-standing policy at EPA that assumes all polymers are safe.

In 1984 EPA crafted what became known as the polymer exemption.  Expanded in 1995, the exemption assumes that almost all polymers are safe under the Toxic Substances Control Act (TSCA), or in the words of the rule, they do “not present an unreasonable risk of injury to human health or the environment…”.

By the time of the 2006 phase-out agreement, however, some EPA scientists were concerned that fluoropolymers might not deserve the exemption, and that they might in fact be a major source of PFOA and other PFCs in people and the environment.

In December 2005, as part of a Dupont-EPA settlement in a related PFOA enforcement action, EPA required Dupont to conduct a fluorotelomer-based product biodegradation testing – an important and essential step since telomer-based fluoropolymers may pose a risk to people and the environment.  Telomers are small, or low molecular weight PFCs that are the building blocks of fluoropolymers.

The experiments were to be completed by the company by December 2008.  But the company failed to produce the data, and under an EPA-industry deal signed in the last days of the Bush administration, Dupont received a three-year extension. This may not be enough, however, to save fluropolymers.

2009 EPA study may have solved the mystery
A study published on July 1st of this year by EPA’s National Exposure Research Laboratory found evidence that fluoropolymers like Teflon and other stain resistant, waterproofing and grease repelling commercial and consumer chemicals could break down into the PFCs found in the environment, including PFOA and PFOS.

Industry has claimed that fluoropolymers are stable in the environment for 1,000 years or longer.  Agency scientists found that fluoropolymers degrade much faster than industry has claimed, with half-lives of just 10 to17 years.  The implications of the study are significant: fluoropolymer-based consumer goods may well be a source of PFC contamination in people.

EPA findings contradict industry
The new EPA findings are quite different than the DuPont corporation’s in-house study, published in the February 2008 issue of Environmental Science & Technology, which concludes that a typical fluoropolymer would have a “biodegradation half-life of 1,200−1,700 years.”

Two reasons may have contributed to DuPont’s finding:

  • DuPont’s scientists used an impure polymer material in their experiments that was contaminated with residual monomers, making it almost impossible to detect polymer degradation.
  • The study was based on an ineffective extraction procedure, involving solvents poorly suited for total recovery of fluorochemicals in the mixture.

As chief of the EPA’s exposure assessment branch, Cathy Fehrenbacker, observed in a companion environmental news article in the same issue of ES&T, the DuPont study lacked “adequate data on rates of biodegradation.”

The EPA study, in contrast, started with a fluorotelomer polymer that was custom made to minimize contaminating residuals. EPA scientists also conducted extensive testing of extraction protocols, assuring much higher recovery of starting polymer and polymer degradation products.

If indestructible fluoropolymers aren’t benign, what next?
The critical question now is what EPA regulators do with the National Exposure Research Laboratory’s findings.

Industry scientists have long argued that fluoropolymers are benign because the molecule is extraordinarily stable and too big to pose any health risk.  The fluoropolymer molecule is structured something like a Christmas tree, with a long central trunk and fluorinated side chains, which are toxic, branching off.  Scientists generally agree that the polymer itself, as long as it remains stable, is unlikely to pose toxicological harm.

The same cannot be said for the side chains.  Industry officials contend that the bond between the central trunk and branches is so strong that breakage is unlikely to occur, so fluoropolymers should be considered benign.

But many independent scientists disagree – and EPA scientists have come around to their point of view.

Since the late 1990s, scientific evidence has been building that the non-fluorinated portion of fluorochemicals can undergo degradation.  As demonstrated by the EPA study, this includes the bond between the polymer’s trunk and fluorinated side chains. In contrast, once “fluorinated branches” break off, they are extraordinarily persistent in the environment.

Bacteria, UV light, strong acids – you name it – are all powerless to degrade PFCs.  Wastewater treatment actually increases the amount of free PFCs in the effluent, probably because wastewater bacteria “bite off” those fluorinated side chains from the main polymer backbone. Similarly, unless incineration is finely calibrated to ensure complete destruction, it could easily liberate free PFCs rather than destroy them.

This persistence of PFCs stems from the extreme stability of the carbon-fluorine bond.  A recent expert review called the C-F bond the “strongest bond in organic chemistry.”

Plainly spoken, fluorinated molecules such as PFOA and PFOS are virtually indestructible.  A staggering prospect given their toxicity.

Today, with virtually no government oversight, fluoropolymers can be found in a vast array of consumer and industrial products, from the coatings of butter and microwave popcorn boxes, to stain- and water-resistant fabrics to cookware, automobiles, paints, building materials and electronics.

Fluorochemical producers call their products “Dependable. Essential. Safe.” As a website backed by the Society of the Plastics Industry claims: fluoropolymers are “super plastics” that are “integral to a clean environment.”

We now know that these amazing chemicals can add another adjective to the boast. Super plastics – super dangerous.  And if fluoropolymers are a source of PFCs in people and the environment, they’ll be super dangerous for a long time to come.

Learn the basics about PFCs and how to avoid them.

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