Scientists Still Tracking Source Of 'Teflon Chemical'

May 15, 2006

By CHERYL HOGUE

 

The so-called Teflon chemical continues to make headlines. This synthetic compound, known as PFOA (short for perfluorooctanoic acid) or C8, is found in the blood of most people around the world, including you and your audience. But just where this chemical is coming from remains an open question.

Since Science Survey last examined this compound in the spring of 2004, a lot has happened on PFOA. Perhaps most memorable was the $16.5 million settlement, announced in December 2005, that DuPont is paying to settle allegations that it withheld information on PFOA from the U.S. Environmental Protection Agency. A month later, DuPont, now the sole U.S. manufacturer of PFOA, announced it would curb its worldwide emissions of the chemical 95% by 2010, based on its releases of the compound in 2000. Other companies are starting to follow suit.

A lot has happened on PFOA on the science front, too.

In February, science advisers recommended that the EPA classify the substance as a "likely" human carcinogen. This would upgrade findings in a 2005 EPA document of only "suggestive evidence" that the compound poses a cancer risk.

Meanwhile, scientific papers continue to come out analyzing human blood for the presence of PFOA and are looking into possible health effects associated with exposure to the chemical. And researchers are expanding their investigations beyond PFOA to related chemicals, called perfluorocarboxylates (also known as perfluorocarboxylic acids), which could be toxic too.

While PFOA exposure is widespread and manufacturers and makers of the chemical are working to reduce releases from factories, scientists still aren't certain just where the substance in our blood is coming from.

People living near DuPont's big plant near Parkersburg, W.Va., have a pretty good guess where the C8 in their bodies came from. Releases from that factory, which uses PFOA to manufacture the Teflon plastic used to coat non-stick cookware, entered their water supplies. Those residing near the 3M facility in Cottage Grove, Minn., that formerly made PFOA may also suspect an industrial discharge as the source of their exposure to the chemical. And folks living near the DuPont plant in Fayetteville, N.C., that has manufactured the substance since the end of 2001 are increasingly concerned about PFOA contamination of local waterways and wells.

But people living in, say, Texas, California or British Columbia who have never lived east of the Mississippi River, much less near a plant that makes or uses PFOA, wonder how the heck this chemical got into their blood. And despite the insinuation, through the use of the term "Teflon chemical," of some environmental activists that nonstick cookware is the culprit, virtually no PFOA is found in Teflon-coated skillets and pots. PFOA is added to the industrial process for making the plastic used to coat pans but the plastic itself, polytetrafluoroethylene, is widely recognized as benign.

Beyond DuPont's version of polytetrafluoroethylene, which carries the brand name Teflon, this plastic is widely used in other brands of nonstick cookware, Gore-Tex and other breathable, waterproof fabrics, computer cables, and other applications and products made by other companies.

Scientists are beginning to fall into two camps on the source of the PFOA in the blood of the majority of the U.S. population. DuPont scientists such as Robert C. Buck say most of the PFOA in the environment comes from industrial discharges, such as releases by the West Virginia plant. They predict that efforts by chemical companies to cut releases of PFOA will stop this pollution problem.

But the uniform distribution of PFOA and compounds chemically related to it in the remote Arctic led another group of scientists to a different conclusion. That group, led by Scott A. Mabury of the University of Toronto, believes the source of these chemicals in the Arctic – and in most people – isn't all due to direct industrial release of PFOA.

Instead, Mabury makes a case that a family of chemicals called perfluorotelomer alcohols is also to blame. These substances are part of what makes Stainmaster carpets and specially treated trousers and shirts repel stains and imparts greaseresistance to the paper used to line pizza boxes and microwave popcorn bags. The alcohols are chemical cousins to PFOA.

Through laboratory experiments, Mabury and atmospheric chemist Timothy J. Wallington of Ford Motor Co. determined that these alcohols break down in the atmosphere to form PFOA and perfluorocarboxylates. In addition, laboratory studies in rats and microbes show that small amounts of the alcohols get broken down in cells into PFOA and related compounds. Some compounds formed during this breakdown process may be more toxic than PFOA, Mabury adds

The outstanding question, according to Mabury, is how the alcohols get into the environment.

They could be emitted from industrial facilities. In this case, efforts by companies that make the alcohols to rein in emissions could stop the contamination. DuPont and Ciba Specialty Chemicals have pledged to curb their releases of these alcohols, and other manufacturers of these chemicals are deciding whether they will follow suit.

But stain- and grease-resistant carpets, paper, and fabric also could release the chemicals after they are on store shelves or in consumers' homes, according to Mabury. Also, when carpets age, stain-resistant pants get worn and pizza boxes get discarded, they may also release the alcohols, he says.

Additional scientific studies are under way to determine whether substances used to impart stain- and grease-resistance break down into PFOA. As part of its settlement with EPA, DuPont will sponsor tests, to be conducted in private labs not owned by the company, to evaluate whether nine DuPont chemicals might break down into PFOA.

Meanwhile, academic scientists and chemical companies are developing replacement compounds to make the products that now contain the alcohols. Some are already on the market.

The pieces of the PFOA puzzle are beginning to fall into place. But what the emerging scientific information will mean to the health of you and your readers, listeners, and viewers with PFOA in your bodies, remains to be seen.

Cheryl Hogue, a reporter for Chemical & Engineering News, won't buy stain-resistant carpet or clothing but makes a mean stir fry in her non-stick skillet.

** From SEJ's quarterly newsletter SEJournal Sping, 2006 issue

 

Sorting out those "p" chemicals:

Perfluorocarboxylates: These are chemical cousins to PFOA. They apparently come from the breakdown of perfluorotelomer alcohols.

Perfluorooctanoic acid: Also known as PFOA or C8, this chemical is an industrial processing agent.

Perfluorotelomer alcohols: Often called telomers for short, these chemicals are used to make stain-resistant carpets, clothing that repels stain, and food wraps that help keep grease from soaking through paper.

 Polytetrafluoroethylene: Sometimes called PTFE, this is the plastic used to coat nonstick cookware, make Gore-Tex and other waterproof, breathable membranes, and produce fireresistant computer cables. PFOA is used in the manufacture of 

By CHERYL HOGUE