Teflon and Scotchgard are among the best-known brand names in the world, and have been used in billions of dollars of non-stick and stain-resistant consumer products.
Their use is so widespread, there probably isn't a person in North America who hasn't eaten a meal cooked on a non-stick pan, worn stain-resistant or water-repellant clothing, or had fast food served on a greaseproof wrapper.
But after nearly five decades of extensive consumer and industrial use, some of the chemicals behind the popular brand names have been linked to cancers and even deaths in laboratory animals, and Environment Canada is concerned about their impact on wildlife.
Some environmental groups are comparing the chemicals to DDT, the pesticide that was the poster child for the environmental movement during the 1960s before it was banned. But while DDT eventually breaks down into less-harmful substances, these new chemicals don't appear to degrade under any known biological process.
“A good way to think about it is as the DDT of this millennium,” said Richard Wiles, vice-president of Environmental Working Group, a Washington-based environmental organization that was one of the first to question the safety of the chemicals. “The fact that they last forever really raises the stakes. Even DDT goes away after decades or centuries.”
DuPont Co. said its Teflon frying pans and other kitchenware are safe if used properly.
Health Canada says human exposures to the chemicals aren't high enough to be a concern.
“When you're using the cookware as it's intended to be used, at the temperatures it's intended to be used, it's perfectly safe,” said David Boothe, DuPont's global manager for such products as Teflon.
The chemicals are part of a broad family of substances known as perfluorochemicals, which use the elements fluorine and carbon to make non-stick and stain-resistant coatings. Perfluorochemicals have a molecular structure that prevents them from mixing well with water or oil, which is why they are so useful in making such consumer items as French fry wrappers that stop grease and raincoats that shed water.
Scientists in the United States have zeroed in on two members of this chemical family as particularly worrisome: perfluorooctanoic acid, or PFOA for short, and perfluorooctanyl sulfonate, or PFOS. They have been used to make some of the world's most-famous brand names, including Teflon and Scotchgard.
Environment Canada has concluded that PFOS levels have reached such high levels in animals like polar bears, which have been found to have more than 4,000 parts per billion in their livers, that they “could be harmed by current exposures.”
Environmentalists say Health Canada did not use the same conservative safety protocol that Environment Canada applied to animals. Using Environment Canada's approach to polar bears, adults and children in Canada would have been deemed to have had excessive exposures and would need to have lower levels to be certain that no health problems are occurring.
Some environmentalists contend that the differing approaches have caused a situation in which chemical safety calculations for wildlife are far more rigorous than those for humans.
“The assessments are more protective of polar bears than human children,” said Rich Smith, executive director of Environmental Defence, a Toronto activist organization.
In an ironic turn for chemicals that are used to make non-stick products, both PFOS and PFOA have been found to have an extreme affinity to stick to living things and, once absorbed, are incredibly hard to shed, often taking decades to be excreted.
“We've never seen them degrade under any relevant environmental conditions,” said Scott Mabury, a chemistry professor at the University of Toronto. “I often say they redefine persistence as we know it.”
The chemicals are found in nearly all North Americans and in almost every wildlife species scientists have tested. Health Canada scientists checking PFOS levels in humans found them in every one of 56 Canadian volunteers tested, according to a paper published in 2004.
