Ohioans living near a plant where DuPont makes Teflon might have levels of the chemical C8 in their blood that are higher than the average level found in plant workers, according to a model developed by company scientists.
Estimates based on DuPont’s model also suggest that the concentration of C8 in the blood of plant neighbors could be higher than levels found to cause health problems in animals.
DuPont has been measuring C8 in the blood of its employees since 1981 at its Washington Works plant along the Ohio River west of Parkersburg, W.Va.
The chemical has been used there for more than 50 years to keep Teflon and similar coatings from clumping during the manufacturing process. It has been detected in wells that supply water to residents in Athens, Meigs and Washington counties.
Nobody outside the plant has been tested, according to DuPont, and few outside the company know how to measure C8 in blood. But in October 2001, DuPont scientists developed a mathematical model that they said could estimate C8 blood levels based on how much of the chemical people were exposed to through air and water.
DuPont’s model is among hundreds of company documents obtained by attorneys for plant neighbors in West Virginia who have filed a class-action lawsuit accusing the company of contaminating drinking water and air with C8, also known as ammonium perfluorooctanoate.
“These affected local communities include numerous sensitive subpopulations, such as the elderly, pregnant women and infants,” Robert Bilott, a Cincinnati attorney for plant neighbors, wrote in a Feb. 3 letter that made federal and state regulators aware of DuPont’s blood model.
The Dispatch obtained a copy of the letter last week from the Ohio Environmental Protection Agency.
DuPont says C8 levels in the air and water near the plant are not harmful. The company also says the chemical is removed before Teflon is applied to cookware, clothing and other products sold worldwide.
In an interview Friday, company officials said C8 blood levels in plant employees who don’t work with the chemical are lower than levels detected in those who do. As a result, they said, the levels in people who live near the plant also should be lower.
“Residents should not be concerned about health effects from C8,” said Robert Rickard, director of DuPont’s research laboratory. “We don’t believe there is a medical reason to test the blood of people in the community.”
The Dispatch reported last month that research dating from the 1970s by DuPont and 3M, once the chief supplier of C8, shows that the chemical builds up in human blood, doesn’t break down in the environment and might cause health problems such as cancer, liver damage and reproductive and developmental defects.
3M also has detected low levels of C8 from undetermined sources nationwide in the blood of people and wildlife and in foods such as apples, bread, green beans and ground beef.
C8 isn’t regulated, but concerns about the chemical’s persistence and its potential health effects led the U.S. EPA to launch an investigation in September that could lead to national standards. Ohio officials are waiting for guidance from federal regulators before deciding how to act.
Under pressure from the U.S. EPA to curb the spread of C8 and related chemicals, 3M announced in May 2000 that it would stop making them. DuPont now makes C8 in Fayetteville, N.C.
Company documents show that DuPont has grappled for more than two decades with how to curb exposures to C8. Employees wear protective equipment, but Ohioans didn’t know until last year that they were being exposed to the chemical.
Under an agreement with the U.S. EPA, DuPont must reduce air emissions of C8 to half of 1999 levels by the end of this year. The company also has installed equipment to strip the chemical from wastewater dumped into the Ohio River.
DuPont cut emissions of the chemical by 76 percent during the past two years, said Paul Bossert, plant manager. “Our goal is to drive all emissions to zero.”
In 1987, DuPont’s chief toxicologist said the acceptable level of C8 in the blood of workers was 500 parts per billion. A July 7, 1987, memo stated that employees whose C8 blood levels were half that “will be required to be removed from the exposure.”
The memo said DuPont’s medical director wanted the company “to place the highest priority” on reducing C8 emissions into the environment but said “our employees will continue to have C8 in their blood.”
DuPont never established an official limit for C8 in blood. Company scientists decided one wasn’t needed, Rickard said. “There was no need to set an action level because there are no known human health effects.”
DuPont’s blood model, which Rickard requested, estimates that long-term exposure to C8 levels detected in water and air on the Ohio side of the river could result in blood levels as high as 3,600 parts per billion, more than twice the average level of 1,530 parts per billion that DuPont has reported in employees who work with the chemical.
Long-term exposure to C8 concentrations of only 2 parts per billion in water — the level detected in tap water provided to 12,000 customers of the Little Hocking Water Association in Athens and Washington counties — would lead to blood levels of 600 parts per billion, according to the DuPont model.
Scientists who developed the model said the blood levels would be reached only after repeated exposure for more than six years.
There has been no routine testing of air and water concentrations of C8 through the years, but DuPont has known that Little Hocking’s wells were contaminated since at least 1984, court records show.
“I’ve been drinking the water for quite a while, so I’ll be the first in line to get my blood tested if anybody offers,” said Lyle Dayhoff, a retired medical technologist who helped start the Little Hocking Water Association more than 30 years ago.
DuPont says C8 is not known to cause any health problems in people, but company documents show that DuPont and 3M have been concerned about tests that show connections between C8 and health problems in animals.
Low-level exposures over time could lead to C8 concentrations in human blood that are higher than levels that have caused kidney damage and developmental defects in rats, according to a report from a scientist hired by plant neighbors.
“The inability of humans to efficiently excrete (C8) potentially makes the chronically exposed human uniquely susceptible to (C8) toxicity,” wrote David Gray of Sciences International, a Washington, D.C., company that does consulting work for the U.S. EPA and others.
Long-term exposure to the chemical, Gray wrote, “has not been directly factored into any risk estimation to date.”
DuPont and 3M say the rat studies aren’t relevant to people, but the U.S. EPA is conducting its own review of the research.
Toxicological studies in rodents and primates have shown that exposure to (C8) can result in a variety of effects, including developmental/reproductive toxicity, liver toxicity and cancer,” EPA scientists wrote in a Sept. 23 memo to other agency officials.
Some people who live near the plant say they aren’t satisfied with responses from DuPont or from regulators in West Virginia and Ohio. They soon might have an independent source of information from a researcher who wants to study C8 blood levels in the area.
“I do not think that it is really clear what the actual levels of C8 are in nearby community residents or whether the C8 levels would be as harmless as some have implied,” said Edward Emmett, a professor of occupational medicine at the University of Pennsylvania.
Models such as the one DuPont developed shouldn’t take the place of clinical studies that can answer questions about how people are being exposed to C8 and how it might affect their health, Emmett said.
“The uncertainty is increased by several possible exposure routes,” he said, “and by the remarkable persistence of C8 both in the environment and in people.”