Non-Stick Chemical Sticks around too Long

posted on:
August 16, 2004

author:
Staff

category:
Environmental

 Concerns about the safety and persistence of the chemical that makes your carpet stain-resistant or your Teflon frying pan non-stick have prompted Environment Canada to clamp down on the non-stick coating industry. 

The worry focuses on fluoropolymers used in Stainmaster carpets, Gore-Tex fabric, Teflon frying pans, medical equipment tubing and the oil-repellent wrappers used by fast food restaurants to serve hamburgers. Fluoropolymers break down into perfluorooctanoic acid, or PFOA, which manufacturers have used as a plasticizing agent in the production of non-stick coatings since the 1940s, when U.S. chemical giant Du Pont developed Teflon.

PFOA and its sibling compounds “redefine persistence, meaning longevity, as we’ve come to think of it,” said Scott Mabury, a University of Toronto chemist.

“There are rocks that break down faster than PFOA,” said Timothy Kropp, a toxicologist and senior scientist with the Environmental Working Group, a non-profit research organization in Washington, D.C.

A series of studies by researchers at the University of Toronto convinced Environment Canada to ban three new fluorochemicals in July under the Canadian Environmental Protection Act. Companies looking to import or manufacture new chemicals in Canada must seek approval from the federal government.

“We don’t understand all of the chemistry and the freight elements at this point but we do know that we have concerns,” said Robert Chenier, chief of assessment for Environment Canada’s environmental protection service. “So we are taking actions now to address what we can actually deal with on an immediate basis.”

As for fluorochemicals currently approved for import or manufacture in Canada, Mr. Chenier said it is still too early for the federal government to act.

Research carried out over the past two years has found the chemical has spread throughout the world, is toxic and has a dangerously long environmental lifespan. Advances in chemical analysis have enabled scientists to examine levels of the chemical in the livers of polar bears, and the amounts are worrying.

At the same time, studies have found PFOA in human blood throughout the world at levels approaching those in factory workers who handle the chemical as a matter of routine, Dr. Kropp said. A class action in the United States by employees who worked with the chemical documents alarming birth defects. Dr. Kropp notes that laboratory animal tests have linked PFOA to cancer, birth defects and delays in sexual maturation.

Its persistence means someone no longer exposed to PFOA would still have it in their body for up to 30 years, Dr. Kropp said.

PFOA’s persistence and toxicity led some researchers to call it the next PCB—the oily substance once used as an insulator, coolant and lubricant before being widely banned in the 1970s.

“It’s definitely the next chemical that we’re looking at and saying, ‘Wow, we really shouldn’t have been making that all these decades,’ ” Dr. Kropp said.

While little is known about PFOA’s long-term effects, there is evidence for concern.

Its use by Du Pont drew massive attention recently when the U.S. Environmental Protection Agency charged the corporation with concealing its own 1981 research showing factory workers could pass the chemical to their unborn children. That and other charges could mean US$300-million in fines for Du Pont, which argues it met its legal obligations and filed a response last week.

Meanwhile, a class action out of a West Virginia community that hosts a Du Pont factory has also garnered attention. One complainant in the suit, whose mother was a Du Pont factory worker, was born with only one nostril.

Dr. Mabury’s cutting-edge U of T research team may have solved the mystery of how PFOA is spread through the environment to accumulate in places as far away as the Arctic.

Their research suggests a class of alcohols used in the production of non-stick coatings are released into the atmosphere either at the factory or once the products go to market.

During their 20-day life span, the alcohols, called telomer alcohols, can travel as far as 20,000 kilometres through the atmosphere, undergoing a variety of chemical reactions before eventually degenerating completely into PFOA.

“They are processed by Mother Nature, doing its wonderful job of keeping the atmosphere relatively clean,” Dr. Mabury explained. “It’s truly a very reactive washing machine for all of the gunk that we stick up in it.”

PFOA then descends from the atmosphere, carried by rain or snow, and accumulates in the Arctic—the final destination for much global pollution.

The chemicals then “wind their way back up the food chain, concentrating, bio-accumulating at each stage from the water into zooplankton, into small fish, into bigger fish, into seals [and] ultimately into the polar bears,” Dr. Mabury said.

Fluorinated chemicals have now become the most highly concentrated pollutants in Arctic life, he added.

Something analogous occurs within the human body, where telomer alcohols are broken down into PFOA and deposited in the liver in just the same way the body processes a glass of wine.

The U of T researchers believe that the growing PFOA levels in human blood derive from telomer alcohols released into the air by source points like factories manufacturing stain-resistant carpet.

Perhaps more worrying, sewage treatment plants, with their microorganisms hungry to break down the alcohols, provide an even more efficient route of distribution for the stuff.

In short, we are inhaling PFOA precursors in the air and drinking them in our tap water.

But Dr. Mabury worries that as the chemical degenerates stage by stage—morphing from one substance to another, whether in the atmosphere or within the human body—some of the intermediate compounds may be even more toxic than PFOA itself.

Still, his research team cautions that PFOA’s impact isn’t yet wholly understood.

“It’s known to be a rat carcinogen,” said U of T researcher Jonathan Martin. “Whether it’s a human carcinogen or not is another story.”

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