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By Jennifer S. Lee
The New York Times, July 2004
Scientists and regulators
are raising concerns about the potential health and environmental effects of an
important family of industrial chemicals. Those concerns were highlighted
yesterday when the Environment Protection Agency announced it was forcing the
chemical industry to do further research on perfluorooctanoic acid, or PFOA, one
member of that family.
The broader group of
chemicals, known as perfluorinated acids, has been discovered widely in the
environment and in almost all Americans. No human health effects have been
discovered, but E.P.A. officials' concerns were raised by recent toxicological
data in animals.
Since World War II,
perfluorinated acids have become incorporated into many brand-name chemicals
because they repel water and oil and are resistant to heat and chemical stress.
Used in the manufacturing process of Teflon and Gore-Tex, they are released as
breakdown products from Stainmaster, Teflon and the original formulation of
Scotchgard. They are also used to make polymers for aircraft and electronics.
Scientists say the properties that make the chemicals attractive to industry -
their chemical stability and resistance to high temperatures - may potentially
have serious effects on the environment.
Perfluorinated acids do not
degrade. They are widely distributed - showing up in the Arctic, in food samples
and in almost all human blood samples that have been tested. No one has found
that the chemicals have a toxic effect on humans, but early research on animals
shows that at least some perfluorinated acids in high doses have the potential
to be toxic. This combination of traits caught the attention of the E.P.A.
"Though we have
concerns, there is a lot of uncertainty," said Stephen L. Johnson,
assistant administrator of E.P.A.'s Office of Prevention, Pesticides, and Toxic
Substances. "Given the uncertainty, additional scientific information is
needed to determine if regulatory actions are necessary."
Environment groups are
comparing perfluorinated acids to PCB's and DDT, which appeared benign when they
were first introduced. Environmental groups note that PCB's were banned by
Congress in 1976, and less was known about them then than is currently known
about perfluorinated acids. Chlorofluorocarbons, or CFC's, were also prized for
their chemical stability until the 1970's, when scientists discovered that their
accumulation in the atmosphere eroded the ozone layer. But relatively little is
known about perfluorinated acids - where they are coming from, how they travel,
how they get in the human body or their long-term health effects.
"We don't have the data
to do more at this point than to worry," said Dr. Gina Solomon, a physician
with the Natural Resources Defense Council. "All we can do is predict that
the chemical characteristics can add up to a problem." But 3M, which
stopped producing chemicals related to perfluorinated acids in 2000, has
concluded after extensive studies that humans are not at risk. "The bottom
line is that at the very low levels that we find in human serum, there are no
health effects associated with those very low levels," said Dr. Larry
Zoebel, 3M's medical director.
To date, most research on
persistent organic chemicals has focused on those containing chlorine, like
PCB's and CFC's, even though scientist knew that fluorinated compounds were also
persistent and accumulated in organisms. Scientists assumed that because the
bulk of fluorinated compounds were incorporated into polymers – they would not
spread widely in the environment. This assumption unraveled after more
sophisticated technology to detect minute quantities of fluorinated chemicals
became available in the late 1990's. The discovery of the widespread presence of
the chemicals has surprised scientists and regulators, leaving them scrambling
to learn more. "Polar bears and eagles certainly don't buy our
products," Dr. Zoebel said.
The properties of
perfluorinated acids stem from the carbon-fluorine bond, one of the strongest in
chemistry. Perfluorinated, or "fully fluorinated," compounds are ones
in which fluorine atoms have replaced all the hydrogen atoms in the
carbon-hydrogen bonds that are characteristic of organic molecules. The
perfluorinated acids are challenging traditional presumptions of how chemicals
can move and behave, both in the environment and in organisms.
"It's non-volatile.
It's not soluble. How does it get to these remote locations?" asked John
Giesy, a researcher at Michigan State who did much of the early research on
perfluorinated acids for 3M.
In studies released in 2001,
3M reported finding one type of perfluorinated acid in various food sources:
green beans from Mobile, Alabama; a loaf of bread from Pensacola, Florida.; and
in two out of three ground beef samples from Port St. Lucie, Florida. The acids
have also been detected in water in some parts of the country. Some people near
Parkersburg, W.Va., have filed a class action suit against DuPont, objecting to
the presence of one perfluorinated acid in their water.
Studies have found
perfluorinated acids in almost all blood samples taken from the Red Cross across
the country. But scientists do not know whether the chemicals are getting into
people directly, or if they are the breakdown products as human metabolize other
chemicals from the environment. Unlike DDT and PCB's, which increase in
concentration by factors of millions in moving up the food chain, the
perfluorinated acid concentration in organisms does not seem to differ as much
from one species to another. Concentration also does not differ significantly
from children to adults to the elderly, men to women. Unlike DDT, which
accumulates in fat cells, the acids accumulate in the blood.
Perfluorinated acids,
however, are more persistent than DDT or PCB's, which break down over decades.
Scientists say they have been unable to measure how fast perfluorinated acids
degrade. "We don't know if it does degrade," said Dr. Scott A. Mabury,
a researcher at the University of Toronto who has examined the chemicals.
Scientists have not been able to break the acids apart with high temperatures
and strong acids that are found in the environment. "It redefines
persistent as we normally use the term," Dr. Mabury said.
Two years ago, the EPA
became alarmed by 3M's internal scientific studies on perfluorooctane sulfonate,
known as PFOS, including one that resulted in the deaths of all the rat
offspring within four days, a striking result for a toxicology experiment. E.P.A.
regulators pressured 3M to stop producing PFOS. The company went one step
further: as a proactive safety measure, it dropped production of all PFOS-related
chemicals, which represented some $300 million in sales, or 2 percent of the
company's revenue.
That unusual corporate
decision caught the attention of scientists who felt 3M acted responsibly and
quickly. Researchers began following up on 3M's studies. Since then, top E.P.A.
officials have turned their attention to PFOA, which is now manufactured by
DuPont in a North Carolina plant under the name C-8 and is used to make Teflon.
According to a risk
assessment by the E.P.A., the estimated range of exposure for human beings,
based on rat studies, overlapped with what the E.P.A. deemed unacceptable for
toxic substances. "What the E.P.A. is doing right now is a pretty brave
thing," said Kris Thayer, a senior scientist with the Environmental Working
Group, an advocacy group that has put together a searchable database of
documents drawn from E.P.A. and the West Virginia lawsuit (www.ewg.org/reports/pfcworld).
"The bigger question is, How did we get here? How come after 50 years, it's
only now they are doing the toxicology studies?"
Environmental groups are
concerned because internal studies done by the companies have shown that rats
have experienced damage to the immune system, brain, pituitary gland, thyroid
and sex glands when treated with perfluorinated acids. Limited studies with
monkeys have also shown adrenal damage, liver damage, pancreatic damage, lung
damage, decreased thyroid hormone levels and, in some cases, death. But industry
researchers at 3M and DuPont maintain that animals are exposed to levels
thousands higher than the general population will ever realistically face.
"You have designed
those studies to produce an effect," said Dr. Robert Rickard, director of
DuPont's Haskell Laboratory for Health and Environmental Sciences, speaking on
the studies on PFOA. Some scientists say that the amount of some perfluorinated
acids that is turning up exceeds what is being released from known manufacturing
processes.
One study published in
Nature that showed a number of detectable perfluorinated acids were released
from overheating a chemical that is used as a nonstick coating that is similar
to Teflon. (DuPont says that company evaluations have shown no PFOA is being
released from Teflon at temperatures people would normally encounter in their
kitchens.) But Dr. David A. Ellis, an author of the study, noted that most
people were not overheating pots on remote desert islands. Scientists conclude
that the chemicals must be coming from somewhere else.
"If you can measure
concentrations in the Arctic, then mass-wise, it has to be a consumer product
which is huge and volatile," said Dr. Ellis, a chemist at the University of
Toronto. One leading candidate is fluorotelomer alcohols, which
are found in a wide range of household consumer products like hair shampoos, rug
cleaners and food paper products. Unlike perfluorinated acids, fluorotelomer
alcohols are volatile—so they can be carried long distances with air currents.
The
E.P.A. is requiring the
chemical industry to conduct more research on the relationship between
perfluorinated acids and fluorotelomer alcohols, as well as provide information
as to where and how much these alcohols are used. "It's a big Sherlock
Holmes mystery right now," Dr. Ellis said. "We are just trying to
piece it all together."