Issue Date: August 30, 2004
PERFLUORINATED POLLUTANT PUZZLE
The saga of some pollutants starts with a synthetic chemical that is produced commercially for years before it is linked to health problems. Polychlorinated biphenyls (PCBs), widely used as insulating fluids for decades before they were banned in the mid-1970s, are an example.
A similar but more complicated story is emerging for the compound perfluorooctanoic acid. PFOA is used in the manufacture of fluoropolymers including DuPont's Teflon and in breathable, waterproof fabrics. During the manufacture of these materials, PFOA is used as a surfactant but is not incorporated into the end product.
PFOA, which is sometimes called C8, is persistent in the environment. Finding PFOA contamination around industrial sites where the compound has historically been manufactured and used was not surprising. Yet the compound is showing up in the blood of people across the U.S. and the world, including those living thousands of miles from the manufacturing sites [Environ. Sci. Technol., published online July 24, http://dx.doi.org/10.1021/es0493446]. This has surprised many researchers and ignited concern within the Environmental Protection Agency.
Just how the chemical is getting into the global environment remains unknown--though recent studies suggest that soil- and grease-resistant coatings made with fluorinated telomers may break down into PFOA (C&EN, June 14, page 44).
Chemical producer DuPont is catching much flak about PFOA. It is the sole U.S. manufacturer of the compound, and it also makes fluorinated telomers--short-chain fluorinated compounds built up from tetrafluoroethylene. The company faces allegations from EPA that it failed to report data about PFOA contamination from its Teflon manufacturing plant in West Virginia. In addition, DuPont is defending itself against a class-action lawsuit--scheduled to go to trial in October--by people who claim they were harmed by PFOA from the Washington Works, West Virginia, plant that wound up in their drinking water. And an environmental group is calling on DuPont to stop using PFOA in the manufacture of Teflon.
CONTROVERSY surrounds the question of whether PFOA causes health effects. EPA is compiling a risk assessment of PFOA, which will examine a wide range of possible health effects, including developmental problems and cancer, says Charles M. Auer, director of EPA's Office of Pollution Prevention & Toxics. The agency plans to send a draft version of that document to its Science Advisory Board for review in November, he says. Although data show PFOA is occurring in people's blood, scientists still are unsure where all of it is coming from and how it gets into humans.
Robert W. Rickard, chief toxicologist for DuPont, says PFOA poses no health risk to the general population at current exposure levels, about 5 ppb.
"This compound does not cause birth defects in animals," Rickard says. "There are no known effects in humans" from PFOA exposure, he says.
Timothy Kropp, a toxicologist and senior scientist for the Environmental Working Group, says blood levels of PFOA in children have been found to range from 1.9 to 56.1 ppb, with an average of 5.6 ppb. And tests have shown developmental effects in laboratory animals at 40 ppb, Kropp asserts. No laboratory study has found a level of PFOA exposure without adverse effects, he says.
"Every dose tested has been toxic," Kropp tells C&EN. "They haven't found doses that are safe." Developmental effects associated with PFOA exposure include changes in bone structure and organs, Kropp says. The chemical is also suspected of causing cancer of the liver, testes, and thyroid, he adds.
Auer points out that the EPA analysis of PFOA differs from most other risk assessments compiled by the agency. Generally, these documents include data about doses of a chemical administered to laboratory animals and estimates of people's exposure to the substance. This introduces uncertainty about how much of the chemical actually gets into people.
In contrast, the PFOA risk assessment will compare the concentration of the compound in the blood of lab animals to the levels actually observed in people's blood. This means EPA will add fewer safety factors into calculations for the PFOA risk assessment, Rickard notes.
Meanwhile, studies are under way to determine if people are experiencing ill effects from PFOA exposure.
The federal government is funding a study of PFOA in residents who live across the Ohio River from DuPont's Washington Works, the company's plant near Par kersburg, W.Va., that has used the chemical for more than five decades. Edward A. Emmett, professor of occupational and environmental medicine at the University of Pennsylvania School of Medicine, is the lead researcher in the project, funded by the National Institute of Environmental Health Sciences.
Emmett tells C&EN that the project will examine the level of PFOA in the blood of 300 to 400 residents and will analyze the milk of nursing mothers for the chemical. The study will examine whether participants were exposed to the chemical in air or drinking water, either at home or as employees in the DuPont plant. The effort will also screen for early chemical or biological changes in the body that may be potential markers of toxic effects.
Meanwhile, DuPont is conducting a study of employees at its Washington Works plant to see if there is any correlation between PFOA exposure and health effects, Rickard says. Completion of the study is expected by the end of the year. DuPont believes this research will, like other studies of PFOA-exposed workers, show no adverse health effects from the chemical, Rickard adds.
Kropp is skeptical of the DuPont study. He says the study will not look for biochemical changes in workers that would presage health effects such as cancer. "You're not going to find what you don't look for," he says.
Auer says EPA is not currently considering any regulation to control PFOA. Any potential federal measure to control the persistent compound would have to be directed at where the chemical is released to the environment, he says. As of yet, scientists have not determined how people are exposed to PFOA, Auer notes. Now, EPA is trying to gather data to determine whether fluoropolymers or fluorotelomers are the source of PFOA in the environment.
Fluoropolymers are plastics composed of a carbon chain sheathed in fluorine atoms, explains George H. Senkler Jr., director of global technology for DuPont Fluoroproducts. The fluorine provides flame resistance, performance at high temperatures, chemical stability, and release of soils.
In addition to Teflon and waterproof, breathable fabric membranes such as Gore-Tex, produced by W. L. Gore & Associates, fluoropolymers are used in a variety of other applications. They include insulation in the telephone and computer cables strung through the space above ceilings in offices, hospitals, schools, and commercial settings. Asahi Glass Fluoropolymers USA, Daikin America Inc., Dyneon, and DuPont use PFOA to manufacture fluoropolymers in the U.S.
DuPont uses the ammonium salt of PFOA in making Teflon, its brand of polytetrafluoroethylene (PTFE). Senkler explains that to induce polymerization, tetrafluoroethylene is subjected to high pressures and temperatures in the presence of water, an initiator, and PFOA as a surfactant.
FOR DECADES, DuPont bought the PFOA it used in the U.S. manufacture of Teflon from 3M. However, 3M phased out its U.S. manufacturing of PFOA between 2000 and 2002. DuPont began producing the substance in Fayetteville, N.C., at the end of 2001. According to Senkler, DuPont supplies PFOA from the North Carolina plant to its West Virginia facility and to Daikin America. DuPont purchases PFOA from Daikin to supply its PTFE manufacturing in Japan and from Miteni, a wholly owned subsidiary of Mitsubishi, for DuPont's European operations, he says.
The Environmental Working Group is calling on DuPont to stop making PFOA and to cease using it in making the Teflon polymer.
"We've looked for many alternatives to PFOA," Senkler says. But other surfactants tested thus far produce a lower molecular weight polymer lacking the desired properties of compounds made with PFOA, he says.
PFOA is not incorporated into the polymer but generally stays in the process water, Senkler says. All but a trace amount of PFOA is removed when the polymer is dried.
DuPont sells Teflon as pellets or slurry. The company's customers convert the polymer into end-use products such as communications cable or use it to coat cookware.
A study by DuPont being readied for publication shows that PFOA decomposes under high temperatures such as those found in commercial processes for coating cookware with PTFE, Senkler continues.
"In industrial processing [of PTFE], you reach temperatures such that PFOA is decomposed completely. When you look at the product that goes out, there's no PFOA," Senkler says. The end products of the surfactant's destruction are hydrogen fluoride and carbon dioxide, he says.
He adds that DuPont has also tested cookware coated with Teflon, "and there is no PFOA. But when you look at the manufacturing process, it's chemically unreasonable that PFOA would be there simply because of the high-temperature processes used."
While fluoropolymers are under scrutiny because they are manufactured with PFOA, fluorotelomers are also targets of investigation as possible sources of the compound in the environment.
Fluorotelomers are used as surface treatments that impart resistance to soil, stains, or grease. Telomers are widely used to treat carpets, paper used to hold greasy fast foods, and textiles. These chemicals are also used in firefighting foams. U.S. fluorotelomer producers and importers are AGA Chemicals, Clariant GmbH, Daikin America, and DuPont.
PFOA is not used in the manufacture of telomers, and the surfactant is not added to telomer-containing products. However, DuPont analyzed its telomer-containing products about a year ago and found trace amounts of PFOA in some--but not all--of them, says Robert J. Ritchie, director of technology and planning for DuPont Chemical Solutions Enterprise.
"Frankly, we were surprised to find PFOA," he says. The company has determined that "the PFOA is there as an inadvertent by-product of the chemistry" in telomer manufacturing, Ritchie says. DuPont is working to improve its processing to reduce the formation of PFOA in telomer production, he adds.
Rickard says DuPont has assessed whether the trace amounts of PFOA in telomer-treated goods such as stain-resistant clothes or carpets would account for the chemical found in people's blood. Given the miniscule amount of PFOA in these items and because the compound is poorly absorbed through the skin, the company has "eliminated the possibility" that use of these consumer articles would lead to exposure of the general population.
To help unravel the mystery of where PFOA is coming from, EPA is asking manufacturers of fluoropolymers and fluorotelomers to conduct studies on their products. The agency wants to determine whether PFOA is formed during incineration, manufacturing, or aging of items, or by degradation of fluorotelomers, Auer says. The agency is negotiating with a number of chemical producers to do the research voluntarily. EPA is seeking four categories of studies from industry.
One set of tests would involve incineration of fluoropolymers and fluorotelomer-treated articles to see if PFOA is formed, Auer says. The agency and industry are "quite close" to striking a deal for companies to sponsor these studies, he adds.
A second batch of tests would involve aging items made from fluoropolymers, Auer continues. Items that EPA wants tested are cookware with nonstick coatings, the thin tape used to seal threads at plumbing joints, computer and telephone cables that contain PTFE for fire resistance, and membranes used to make fabric waterproof and breathable. EPA wants these items aged through exposure to heat or light, then analyzed to see if PFOA is released. Auer says EPA hopes to complete a deal with industry on these tests this fall.
The third cluster of studies the agency wants involves monitoring the air, water, sediment, and wildlife for PFOA around facilities where fluoropolymers and telomers are produced and used, Auer says. "Users aren't prepared to monitor anything at this time," he says. But the agency is on the verge of finalizing a memorandum of understanding with former PFOA maker 3M and current producer DuPont for environmental monitoring, Auer adds.
The fourth set of studies EPA wants involves biodegradation of fluorotelomers, which recent research indicates break down into PFOA. EPA attempted to negotiate five different types of biodegradation studies with telomer producers, but, "We had a hard time making progress," Auer says. In June, EPA announced it would run the tests itself but would continue talks with companies to get replicate data (C&EN, July 5, page 6).
Once the four categories of tests are completed, EPA likely will have a good understanding of where PFOA comes from in the environment, Auer says.
DuPont is cooperating with EPA and will conduct all of the tests the agency is asking for, Ritchie says. "We have the same sense of urgency as EPA does," he says. "We are really cooperating with EPA to the fullest extent to get to the bottom of this," Ritchie says.
Should data indicate that fluorotelomers are a source of PFOA in the environment, DuPont will "act accordingly" in light of its principles of product stewardship, Ritchie says.
Although EPA and DuPont are working together on determining the source of PFOA in people's blood, the agency is also accusing DuPont of failing to report data on PFOA in the past.
According to an EPA complaint filed in July, DuPont failed for years to tell the agency that it had found PFOA in the umbilical cord of the baby of one of its pregnant workers in 1981. The agency also alleges that DuPont should have informed EPA shortly after it found PFOA in drinking water systems near its West Virginia plant. DuPont was required to report this data under a federal law that requires companies to share data with the agency that indicate a chemical poses a substantial risk to human health or the environment, EPA says (C&EN, July 12, page 18).
DuPont is contesting the allegations. "The small amounts of PFOA that DuPont discovered in a blood sample and in drinking water did not suggest that there was any risk to human health, let alone the sort of 'substantial' risk that is necessary to trigger reporting requirements," the company says (C&EN, Aug. 16, page 17).
THE NEWS of EPA's allegations about DuPont flew around the globe. In recent weeks, Chinese newspapers have reported that merchants were pulling nonstick cookware off their shelves in response to concerns about PFOA. But DuPont spokeswoman Catherine L. Andriadis says the company has surveyed Chinese stores and found nonstick pots and pans still displayed for sale.
EPA hasn't yet announced the size of the fine it will seek from DuPont for the allegations. But in other cases of this magnitude, the agency has waited a few months and collected more information on the facts surrounding the alleged violations before proposing a penalty.
The Environmental Working Group is calling on the agency to hit DuPont with the statutory maximum penalty for the charges, which would total more than $300 million.
For decades, the Washington Works plant has emitted PFOA into the air from drying the PTFE polymer and discharged the surfactant with wastewater into the Ohio River. In the late 1990s, DuPont developed control technologies for PFOA. This equipment has led to a steep reduction in emissions at the West Virginia plant over the past five years, Senkler says. Company figures show that PFOA in water discharges from the plant into the Ohio River dropped from 56,000 lb in 1999 to 5,000 lb in 2003, with an estimate for 2004 of 1,000 lb. During the same time, air emissions fell from 31,000 lb to 6,000 lb, and the 2004 estimate is 400 lb. Meanwhile, DuPont's PFOA manufacturing facility in North Carolina releases less than 100 lb per year, all as air emissions, Senkler adds.
Environmental activists see the PFOA situation, especially the pollution near DuPont's Washington Works, as a continuation of the chemical industry's legacy of hiding information from people exposed to contamination. The situation along the Ohio River is similar to PCB contamination in Anniston, Ala., says Ken Cook, president of the Environmental Working Group. Monsanto produced PCBs in Anniston for decades. Information released as part of the class-action suit revealed that Monsanto knew for years about the PCB pollution in the community from the plant site--but it kept quiet, Cook says.
"We only find out when the companies get sued," he tells C&EN.
"IF IT TRULY is DuPont's corporate philosophy not to disclose information they collect about chemical contamination of their workers' fetuses or the tap water of the communities they operate in, it makes you wonder what else the company knows but isn't telling the public about their products and facilities," Cook says.
"That is the reputation DuPont is building for itself in this Teflon scandal," he adds. "And the corollary is, the public will never really know what DuPont knows about contamination or pollution or when they knew it until someone sues them."
DuPont spokesman R. Clifton Webb says DuPont in 1984 tested tap water from Little Hocking Water Association, a rural Ohio utility with wells across the river from the Washington Works. DuPont found PFOA at the very level of detection for the chemical, Webb says. According to EPA documents, the level found was 0.8 ppb. The company retested the Ohio utility's water three months later and could not detect PFOA, he says. DuPont checked Little Hocking's water in 1987 and 1988 and again did not detect the chemical, he says. Because it did not find PFOA in the water for three years in a row, the company did not test the drinking water in Ohio again until 2002, Webb says.
In addition, DuPont analyzed water from Lubeck, W.Va., which is east of Washington Works. In June 1984, it found PFOA in samples from Lubeck. Tests by the company in 1988 and 1989 again found the chemical in Lubeck's water at levels of up to 2.2 ppb, according to EPA. Webb says DuPont told West Virginia officials about the results in 1989.
"We feel we adequately and appropriately communicated information on PFOA," Webb tells C&EN.
Cook says the data should have motivated DuPont years ago to eliminate releases of PFOA from the Washington Works plant. Once a company gets an inkling that a chemical it uses is pervasive and persistent, the firm should take action, he says. Cook charges that DuPont officials decided that because PFOA wasn't regulated, the plant would maintain business as usual.
Controlling this pollution would have taken only a small percentage of DuPont's profits from Teflon, Cook says.
Whatever the size of the fine EPA eventually seeks from DuPont, controversy will continue over what, if anything, should be done about PFOA. The upcoming EPA risk assessment will probably provide some indication of whether the levels of PFOA found currently in human blood might cause harm. But any government or industry action to control PFOA isn't likely until further research pinpoints where the compound is coming from in the environment and how it is getting into people's bodies.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society