Paper fluorochemicals and PFOA - new Du Pont study adds to debate on grease-resistance chemicals being source of PFOA

A recent publication by DuPont scientists adds to the current debate on whether paper chemicals (and other fluorotelomer-based products used in textiles, carpets etc) are a source of PFOA. This peer-reviewed report describes a long-term study of the degradation of perfluorinated polymers in soil. ES&T online have given a good review of the study and views on the validity of the conclusions and the opinions of key bodies such as the EPA.

The jury is still out:

• PFOA has been shown to cause liver damage, reproductive problems, which has seen it labelled a “likely carcinogen” by the Environmental Protection Agency EPA's Science Advisory Board.
• PFOA is bioaccumulative, has been found widely in the environment and is a big concern.
  
• The DuPont study concludes that the PFOA and PFCAs come from impurities, also known as residuals or precursors, in the fluoropolymer product they tested (stain repellant solution). As a result, they conclude that the polymer degrades very slowly, with a half-life of 1200–1700 years and degrades too slowly to be a current source of PFOA in the environment. Others disagree with the conclusions and have raised a number of valid ponits regarding the interpretation of the results and conclusions drawn from the study.
  

Time for a quick summary of where the paper chemical supply industry is with perfluorinated chemicals (PFCs) such as PFOS (perfluorooctyl sulphonate) and PFOA (perfluorooctanoic acid). Perfluorinated chemicals (PFCs), gained notoriety in the paper chemicals industry when in the late 1990's, 3M Corporation announced they would withdraw their successful Scotchban fluorochemicals from the market. These chemicals were sold for use in grease-resistant paper and board and it became clear that PFOS (perfluorooctyl sulphonate) was detected widely in the blood of humans - PFOS is a PFC and is classified as persistent, bioaccumulative and toxic (PBT). The details and history of PFOS are outlined on the EPA website or in a number of environmental-concern sites (eg EWG). Although the production of products containing PFOS has been stopped, ongoing blood sampling continues to reveal the presence of PFOS (eg WWF and The Co-operative Bank).

The findings on PFOS led the EPA in 2000 to review similar chemicals, including PFOA (perfluorooctanoic acid) to determine whether they might also present concerns. In essence, PFCs accumulate in the environment and have been found in a wide range of wildlife, as well as in humans. There is evidence to suggest that exposure to perfluorinated chemicals such as PFOS and PFOA may cause birth defects, adversely affect the immune system and disrupt thyroid function, which during pregnancy, can lead to many developmental problems (there are a number of references but for example see the WWF or the very effective Environmental Working Group's web sites). The US Environmental Protection Agency also considers both PFOS and PFOA to be carcinogenic and occupational exposure to PFOS has been correlated with increased incidence of bladder cancer.

The generation of PFOS was linked to the electrolytic process used by 3M and a Japanese manufaturer and it was known that the other process used by companies such as DuPont, called telomerisation would not generate PFOS. However, in producing a number of fluorine-based chemicals (not paper chemeicals), PFOA is used as a processing aid and later science showed how PFOA could be produced as an unintentional by-product.

Where are we now with the EPA investigation:

• There is evidence to suggest that exposure to PFCs may cause birth defects, adversely affect the immune system and disrupt thyroid function, which during pregnancy, can lead to many developmental problems.
• PFOS is a by-product of the electrolytic process used originally by 3M and ..... PFOS is classified as persistent, bioaccumulative and toxic (PBT). Paper chemicals produced using the electrolytic process has been withdrawn.
  
• The US Environmental Protection Agency (EPA) "invited" eight companies (DuPont, 3M, Arkema, Asahi Glass, Ciba Specialty Chemicals, Clariant, Daikin and Solvay) to participate in the 2010/15 PFOA Stewardship Program, by pledging to reduce PFOA releases from manufacturing and in products by 95% by 2010, and to work toward the elimination of PFOA and its precursors from emissions and products no later than 2015. All emissions figures are based on a 2000 baseline and the commitments will apply to both to US and global operations. Chemical intermediates that break down to PFOA in the environment are also included as are similar perfluorinated compounds with longer carbon chains.
• PFOA is formed as degradation products of small polymers called fluorotelomers and as the unintended by-product of their manufacture. Fluorotelomers are used in a range of commercial products, including fire fighting foams, as well as soil, stain and grease resistant coatings for carpets, textiles, leather, paper, including fast food packaging, as well as personal care and cleaning products.
• Once released into the environment, perfluorochemicals including PFOA persist and are now widely distributed throughout the global environment. They are reported to be found in food samples and have been detected in almost all human blood samples tested.
• Studies show that PFOA does not break down by any known environmental degradation mechanism that is by hydrolysis, photolysis, or biodegradation.

So, are paper chemical manufacturers and suppliers continuing to sell fluorochemicals containing PFCs or PFC precursors?

• The answer is yes.
• Trademarks of fluoropolymers used to give grease-resistance in the paper and board industry: Zonyl (DuPont), Lodyne (Ciba), Cartafluor (Clariant).

Many environmental-concern groups have worked hard to expose and bring an end to the release of PFOS and PFOA and significant pressure has been put on manufacturers to develop PFC-free alternatives. The big question is why, when it is known that PFOA is persitent, bioaccumulative and toxic, that its release into the environment is not stopped immediately. Reducing emissions between now and 2015 is at least a start.

Are there alternatives to PFC-containing products?

• Fluorine is a unique compound with unique properties so changing to chemistries such as silicone bring a loss of performance. In some applications this lower level of performance could be sufficient. Solvay has an alternative to fluorine. In some applications it is possible to use barrier coatings based on latex formulations and/or waxes.
  
• The smaller molecule, fluorosurfactant-based products were of immediate concern as they would be more likely to be adsorbed by animals. Therefore, an approach has been to favour higher molecular weight fluoropolymers. This does not necessarily remove the hazard as by-products can be generated in the manufacturing process and the polymer itself has the potential to degrade in the environment and generate PFOA (it was this hypothesis which the DuPont scientists were studying).
• Some companies have put effort into C4 and C6 fluorotelomers rather than the traditional C8 chemistry with the view that the environmental and toxicological effects would be reduced. However, there have been no breakthroughs in producing cost-effective paper chemicals so far.
  

Some additional reading:
C&EN article
ACS article
CEE Food Industry Article