Study: Teflon® Byproduct Might Harm Environment
But experts and DuPont say there's no threat to human health
WEDNESDAY, July 18, 2001 (HealthDayNews) -- A group of chemicals that include Teflon® can break down into compounds that might pollute the environment for decades, says new research.
A study in tomorrow's issue of Nature reports that when fluoropolymers -- the most famous of which is DuPont's Teflon® -- are heated to very high temperatures, they create substances that in high concentrations can harm plants. However, experts say the findings don't suggest any direct danger to humans.
And DuPont says there is no evidence that Teflon®-coated cookware has ever caused any "serious, chronic or acute" health problems during normal use.
Teflon® was discovered in 1938 by Roy Plunkett, a chemist working at DuPont's Jackson Laboratory in New Jersey. It is the most slippery material known. In 1946, DuPont began to sell Teflon®-coated cookware, fabrics and textiles. Today, it's also widely used in the aerospace and electronic industries and in many industrial processes.
Scott A. Mabury, an associate professor of environmental chemistry at the University of Toronto, is co-author of the new study. His team was studying fluoropolymers to find out why so much of a substance called trifluoroacetic acid (TFA) was in the environment.
In the 1980s, scientists determined chlorofluorocarbons were responsible for thinning the ozone layer. The chemicals were banned, but to fill demand, chemical companies developed hydrofluorocarbons.
Thomas M. Cahill, a post-doctoral researcher at the Canadian Environmental Modelling Centre who is familiar with Mabury's study, says hydrofluorocarbons "differed from the chlorofluorocarbons in that they broke down fairly rapidly and did not deplete stratospheric ozone." The hydrofluorocarbons formed TFA, but not enough to account for the amounts found in environmental tests.
Mabury found that when fluoropolymers were heated, they indeed formed TFA. Furthermore, he says they also could form perfluorocarboxylates, which accumulate in animal tissues, including humans.
Are perfluorocarboxylates dangerous to humans?
"There's no definitive answer yet," says Mabury. He says fluoropolymers probably are not the primary source of the perfluorocarboxylates found in humans.
Both Mabury and Cahill say the findings don't suggest a direct health danger.
"TFA is effectively non-toxic to mammals. It's fairly easily excreted, and it's not very biologically active," says Cahill.
"It is weakly toxic to plants, so it's more of an environmental concern than a human health concern," he says. "I'd have no qualms baking on a Teflon® frying pan. What is actually emitted is a gas, so it's going to bake off in vapors and then react in the atmosphere to form TFA. So it's not forming TFA, or at least not much, directly in your food."
In a statement, DuPont defended Teflon®, saying tests have shown the coatings don't begin to degrade unless heated to temperatures of 660 degrees Fahrenheit or greater. The statement says, "The study referred to in the Nature magazine article involved heating the fluoropolymers to temperatures as high as 932 degrees Fahrenheit, hundreds of degrees higher than would be realized in a kitchen environment."
Cahill says scientists are concerned that TFA won't go away. While it easily dilutes in water, it won't evaporate. So, if it gets into a water system that has no escape, such as a pond, it could accumulate over years.
"The fear is that you could accumulate TFA over multiple seasons, resulting in higher and higher concentrations in these ecosystems that lack water outflow until eventually you get to a point where you might see toxic concentrations in plants," he says.
"Right now, the concentrations in rainfall are [1000-fold] lower than the concentrations which are known to cause toxic effects (or slowed growth) for the most sensitive species of plants tested," says Cahill. "In a couple of terminal water bodies, we got concentrations that were only [a 100-fold lower] than toxic concentrations. You're far from toxicity values."
But if a toxic effect from TFA shows up down the line, scientists fear it will be hard to clear.
"We're still suffering the consequences of DDT, and it's 30 years after most industrialized nations banned it. TFA is probably more stable than DDT by a long shot. It's going to be in the environment for a while," says Cahill.
Scientists now are scrambling to learn as much as they can about TFA, and Mabury says it's too early to call for any changes in the use of fluoropolymers.